Tecplot 360 allows me to reduce computational efforts and propose ideas for a strong, physics-based turbulence model.Ryuichi Nagaosa

Interview | Summary | Animations | Beta Program

Ryuichi Nagaosa, Ph.D. is a faculty research associate with the Center for Environmental Energy Engineering at the University of Maryland. A chemical engineer, he specializes in transport phenomena in the environment. His primary interest is turbulence and environmental fluid mechanics and their impact on the environment. More specifically, his research focuses on the study of turbulent heat and gas exchanges at the atmosphere-ocean interface.

Producing beautiful snapshots of turbulent vortices is one of my hidden hobbies as an amateur artist. These snapshots were produced in very close collaboration with my Norwegian colleagues, Prof. Guttorm Alendal and Dr. Lars Inge Enstad, at the University of Bergen. When I was invited to be a guest scientist at the Nansen Environmental and Remote Sensing Center, we enjoyed several observations of the structures of turbulent vortices based on our numerical experiments. Published in Physics of Fluids, 18,055106 (2006),by Lars Inge Enstad, Ruichi Nagaosa and Guttorm Alendal.

Nagaosa also serves as a senior research scientist at the Research Center for Compact Chemical System, AIST (National Institute of Advanced Industrial Science and Technology) in Tsukuba, Ibaraki, Japan. He also was a visiting scientist at the Nansen Environmental and Remote Sensing Center, a nonprofit climate and environmental research foundation affiliated with the University of Bergen, Norway.

Early in his career, Nagaosa chose computational techniques as his preferred method for evaluating environmental fluid mechanics. For more than 15 years he has used Tecplot 360 software, a numerical simulation and computational fluid dynamics (CFD) visualization tool that creates state-of-the-art visual reproductions to quickly make sense of vast amounts of complex information. He uses the software as a communication tool for risk assessment of hazardous materials leakages in a closed space, and also to show the spread of the hazardous gases in our residential space.

It is Nagaosa’s belief that “inspirational-based thinking” will help us understand turbulence dynamics. In his view, this is the role of the engineer. We recently interviewed Nagaosa about his research and his use of Tecplot 360 software.

Interview

Q. 1. How did you become interested in engineering?

A. 1. When I was a high school student and a university undergraduate, I loved math. And I decided to become an engineer because I believe that in our world, inspiration-based thinking will help us. Engineers provide this kind of thinking.

Q. 2. How did you come to choose turbulence as your area of study?

A. 2. I entered the department of chemical engineering and chose to join the fluid mechanics lab when I was an undergraduate. My supervisor was a specialist in turbulence research and laboratory experiments. I have been influenced strongly by his method of research for 20-plus years. I chose a computational technique as my research tool, rather than experimental fluid mechanics.

Q. 3. Why is turbulence in the atmosphere and ocean significant?

A. 3. Fluid flows in the environment are turbulent, including atmospheric and oceanic flows. Let’s consider gas transport from the atmosphere into the ocean, across the ocean surface. The concentration of the gas in the ocean varies drastically, mainly as a function of the distance from the surface. And these concentration profiles have large gradients at the interface.

In general, gaseous materials are more easily spread in air than in water. This means that the gas transport in water is much slower than that in air. Therefore, I assume that the concentration of the materials in air is uniform in space, because of its quick spread in air. Using this assumption, my attention is concentrated on computing the concentration profiles of the material only in water. This assumption is also helpful to reduce computational efforts by skipping computations of the concentrations in air.

On the other hand, I deeply understand the importance of the spread of the material in air on some occasions, for example, on a case that turbulent flows in air induce waves at the water surfaces, and consequently, turbulence in water. In this case, spread of the gas in air is not so quick at the wave crests, and we should consider this in our computations. In the near future I hope to compute the interactions of turbulent flows in air and water accompanied by the gas exchange, to understand more physically complex phenomena.

Q. 4. What Challenges Do You Face When Conducting Your Research?

A. 4. Gaseous material and heat are exchanged between the ocean and the atmosphere, and these exchange rates are determined mainly by turbulence in the ocean below the interface. Measuring small turbulent flow structures near the interface is difficult in laboratory and field experiments. My goal is to quantify turbulence in the ocean, interactions of turbulence with the interface, and the mass balance between the atmosphere and the ocean, by applying a computational technique. Many assumptions are required to perform these computations, and a significant investment of time. Tecplot 360 allows me to reduce computational efforts and propose ideas for a strong, physics-based turbulence model.

Q. 5. What are the goals of your research?

A. 5. My ultimate goal is to study turbulent flows and heat and gas exchanges across the atmosphere-ocean interface and to model exchange rates in a systematic way without having to use massive computational resources. For example, if we can evaluate the exchange rate of CO2 using only a few snapshots of the ocean surface velocity profiles or near-interface wind profiles, we can more easily understand a large part of global carbon cycles.

Tecplot 360 allows us to view flows in a beautiful and vivid manner, and this enhances our understanding of engineering and environmental science. We can also establish parameters to help predict turbulence characteristics without using complex statistical procedures. Published in the Journal of the American Institute of Chemical Engineers, 58, 2012, pp. 3867-3877, by Ryuchi Nagaosa and Robert A. Handler.

Q. 6. Why is it important for us to understand atmosphere-ocean dynamics?

A. 6. The ocean surface is one of the major entrance points for transfer of important gaseous materials such as CO2 and O2, as well as thermal energy, moisture, and so on, from the atmosphere. The interface can also be disturbed by­ waves generated by wind, which can alter the gas exchange mechanisms between the two flows. And, as explained earlier, turbulence in the ocean can be a major factor in determining gas exchange rates. On these points, the interaction of the atmosphere and the ocean is very important.

Q. 7. You spoke about ocean acidification due to CO2 transfer. Will you please explain this and why it is significant?

A. 7. Others have expressed concern that CO2 uptake across the atmosphere-ocean interface causes acidification of the seawater, posing potential environmental and ecological impacts (Caldeira, M. Wickett. Nature, 425 (2003), 365). Acidification is caused by a series of chemical reactions of CO2 absorbed into the ocean, and we must understand the effect of turbulence on these chemical reactions. My preliminary computations on the gas exchange across the interface show that the chemical reactions enhance gas exchange rates. In the near future I will investigate these reactions more fully.

Q. 8. How will your research expand our knowledge about global warming?

A. 8. My goal is to understand environmental fluid flows and the global carbon cycle. I do not believe that scientists and engineers can the stop deterioration of the environment. However, I know that we can notice dangers and their significance, and propose alternative technologies to save the earth. Policymakers and politicians have a greater role in saving our environment. However, we can propose solutions based on scientific knowledge. I believe that to understand the earth will help us save it.

Summary

Tecplot 360 software enables visualization of fluid dynamics, including turbulence in the atmosphere and ocean, so we can achieve better scientific understanding. The software is very helpful in visualizing vortices in water turbulence.

Observing details of turbulent flows and concentration profiles of gas transferred from the interface toward turbulent water greatly inspires me. One example of my findings using the software is to propose a detection strategy to extract “vortex” in the near-interface region of turbulent water. Published in the Journal of the American Institute of Chemical Engineers, 58, 2012, pp. 3867-3877, by Ryuchi Nagaosa and Robert A. Handler.

Producing beautiful snapshots of turbulent vortices is one of my hidden hobbies as an amateur artist. The snapshots at the beginning of this article were produced in very close collaboration with my Norwegian colleagues, Prof. Guttorm Alendal and Dr. Lars Inge Enstad, at the University of Bergen, when I was invited to be a guest scientist at the Nansen Environmental and Remote Sensing Center. We enjoyed several observations of the structures of turbulent vortices based on our numerical experiments.

Animations

Development of Fluid Velocity and Gas Concentration Mapping

• This animation shows time development of fluid velocity and gas concentration mapping at a location very near, but not at the interface.
• The animation also illustrates a view of the turbulent flow from above the gas-liquid interface, looking downward.
• Red and blue mapping indicate the gas concentration of positive and negative deviations from the time-space average.
• We can observe an intermittent emergence of blue colors (low concentration fluid) from inside the turbulent flow, and the fluid can exchange the gas across the interface very extensively.

Turbulent Vortex Structures

• This animation shows a perspective view of time development of turbulent vortex structures extracted by the formula used in Ref.[1].
• Many turbulent vortex structures are generated in the turbulent flow, and at some places, these structures interact with the gas-liquid interface.
• Time-development of fluid velocity mapping and vortex structures in an x-z plane is also animated in this, but the mapping is difficult to distinguish in this animation.
• Animation 3 focuses on the dynamics of turbulent vortex structures.

Turbulent Vortex Structures – side view

• This animation shows time development of the turbulent vortex structures by looking at the flow from its side.
• The gas-liquid interface is located at the top boundary of this animation.
• Red and blue mapping indicate the vorticity fluctuations from the time-space averages.
• Red and blue mapping of the vorticity signify the fluid flow of clockwise and anti-clockwise rotations.

Join the Beta Program

Tecplot invites you to join our new Tecplot 360 Beta program! We are happy to announce the first beta-release of the new Tecplot 360–with improved user interface and streamlined file loading. Click here to get the details

Michael Connelly recently retired from his position of modeling contaminant migration in ground water flow at Washington State’s Hanford Nuclear Reservation.  Mike has been using Tecplot 360 to visualize and plot the results of his simulations.  Over the years, he has become quite proficient at creating add-ons to extend Tecplot 360’s capabilities.

Mike’s most recent add-on is called LocateZonesMinMax. It provides the minimum and maximum for a single zone or group of zones.  The search for maximum and minimum can be restricted to the area/volume shown on screen.

Mike is generously providing this add-on to other Tecplot 360 users at no charge. Thanks Mike! You can contact him to at m.connelly@charter.net to obtain a copy of the add-on, or if you are interested in help with customizing Tecplot for your application (a charge may be associated with additional help).

The usage of LocateZonesMinMax is described below.

First, choose how you wish to specify the zones to be used for the min/max calculation.

• A single zone you specify: the add-on finds the min/max values for the single zone and variable you select.
• All zones: the add-on finds the min/max values for a variable you select in all zones. This can be overridden by choosing zones in the Zone List.
• Active zones: the add-on finds the min/max values for a variable you select in active zones.

To restrict the min/max calculation to data displayed within the frame, mark the “Restrict to data within frame” checkbox. If “After locating, reselect to in frame zones” is marked, the Zone List is updated to display only zones visible in the frame.

After selecting the zone selection methods, actually select a zone or zones in the Zone List, then a variable in the Variable List. If using All Zones or All Active Zones, the applicable zones are already selected, although you may choose different ones if desired. The min/max are immediately displayed when you choose a variable.

You may also choose a zone by clicking in the Tecplot 360 workspace. First click “Use Mouse to Pick Zones,” then click in the workspace. Each zone you click is added to the selection in the Zone List, unless you have chosen to specify a single zone using the Choose Location Type buttons, in which case each zone you click is individually chosen. To clear the selected zones in the Zone List, click “Clear List.” If you have already chosen a variable, choosing different zone(s) automatically updates the min/max displayed in the dialog for that variable.

For both minimum and maximum values, the zone, the Tecplot 1-D array location, the variable number and its I/J/K index, and the actual minimum or maximum value are displayed in their own sections of the add-on’s dialog.

Once you have found the min/max values you are interested in, you can optionally use the following buttons:

• Show Min/Max as scatter symbols. The minimum and maximum will be marked with scatter symbols in the Tecplot 360 workspace. Scatter symbols for other zones are turned off.
• Get Other Values at Minimum (or Maximum) Location. Displays a dialog that shows the values of all other variables at the min or max location. Both cell-centered and nodal values are displayed; one of these will be interpolated depending on the format of the data.

Learn how Tecplot 360 can help you analyze complex data, arrange multiple layouts, and communicate your results with professional images and animations.

Society of Petroleum Engineers Annual Technical Conference and Exhibition

September 30—October 2, 2013 in New Orleans, LA
Tecplot Booth #522

Tecplot is offering complementary 30-minute training sessions in our booth. Learn about displaying fault surfaces and streamlines in Tecplot RS 2013 or discuss the topic of your choice in one-on-one sessions.

Tecplot RS 2013 R1 has added new functionality to Inside Views to identify and display fault surfaces composed of selected cell faces. Three different methods are available to define the faults and users may then select from a list for display in 3D grid plots.

Sign up for training at SPE-ATCE, or call us at 1.800.763.7005 (or email sales@tecplot.com).

Space is limited.

Find out what’s new in Tecplot RS 2013 Release 1 >>

Engineers using Tecplot 360 or Focus often need to create a new variable which is based on a numeric relationship of existing variables already loaded into Tecplot. This powerful capability is simply done using this method:

In Tecplot 360 (or Focus) click on “Data” on the top menu bar, then click “Alter >> Specify Equations” which brings up this menu:

As an example, we will calculate the difference between two variables.

First select All Zones, and then type in the Equation(s) box to initialize the new variable QDifference:

{QDifference} = 0

Click on the “Compute” button

Next we will find the difference for variable Q between zone 2 and 3 (i.e. Q in zone 3 – Q in zone 2) to QDifference:

Select the zones you want to receive the difference value (you could put it in both zones 2 and 3 if you like) and type the following equation:

{QDifference} = {Q}[3] – {Q}[2]

Click on the “Compute” button

The new variable QDifference is now available for plotting.

You can learn more about calculating variables via the “Specify Equations” menu on page 305 of the Tecplot 360 User Manual located here: http://download.tecplot.com/360/current/tpum.pdf

Learn how Tecplot 360 can help you analyze complex data, arrange multiple layouts, and communicate your results with professional images and animations.

The Materials Genome Initiative

Just over two years ago, President Obama announced the Materials Genome Initiative. The name is sort of silly—materials don’t have genes—but the ideas behind the initiative are significant. In short, the goal is to “discover, develop, manufacture, and deploy advanced materials at twice the speed that is possible today”. To do this, we must develop a wide range of analytical techniques that will allow materials to be designed from “first principles” analyses.

At a recent aerospace conference they referred to this as the “atoms to airplanes” initiative.

In the world of chemistry and material science, “first principles” means quantum mechanics. Software has been available for some time to compute the electron wave functions from the material composition (the type and location of the atoms in the material). Loosely speaking, these wave functions give the probability that a specific electron will be at a given location in the material at any given time. Added together, they give the electron charge density – the probability that any electron will be found at a given point in the material at any given time. Together, the wave functions and electronic charge density are the electronic structure of the material.

Scientists know that the properties of materials, and chemicals for that matter, are a function of the electronics structure of the material.  Unfortunately, techniques to compute the bulk properties of materials from the electronic structure have proven difficult to develop. This is, perhaps, the biggest obstacle to the success of the Materials Genome Project. If you can’t compute the bulk properties (modulus of elasticity, etc.) from the material composition (the type and location of atoms in the material), you can’t go from “atoms to airplanes” (or bridges, or buildings, or …).

For the last seven years, Tecplot has been collaborating with a group at Colorado School of Mines, led by Professor Mark Eberhart, to develop software that can compute the bulk properties of the materials from the electronic structure.

The technique is based on the idea that materials with similar arrangements and properties of “chemical bonds” within the material will have similar bulk properties. Chemical bonds are not usually a concept that is applied to materials—primarily because they are so difficult to identify. Our software identifies these chemical bonds using the topology of the electronic charge density. The software,  code-named “ChemBond”, has already shown success in the analysis and design of new steel alloys.

Tim Wilson

Scott Imlay

Tim Wilson from Mark’s group at the Colorado School of Mines joined us over the summer to help complete ChemBond.  This is an exciting milestone for us at Tecplot. If we can create a more robust ChemBond we could help fill a critical gap in the Materials Genome Initiative. In a very real way, we could help change the world!  Stay tuned!

More information about ChemBond >>

Webinar: Oct. 10, 9 am PDT. Reserve your seat now:
https://www1.gotomeeting.com/register/595899344 >>

The dramatic increase over the last decade in the application of Computational Aided Engineering (CAE) in the design process is due, in large part, to the relentless growth of computer performance and the enhanced computer power used to perform a wide variety of high-resolution calculations.

An unintended consequence of the high-resolution methods is very large simulation results with low informational density.

The challenge of analyzing large simulation results with common engineering desktops is impacting modern engineering design strategies.

At Tecplot, we set a goal to develop a solution that would allow engineers to quickly visualize one billion cells on a typical engineering workstation. That goal has been achieved!

Drs. Scott Imlay and Durrell Rittenberg will discuss the strategies used to achieve the dramatic increase in speed using less memory, and will demonstrate its use in analyzing CFD datasets with over 100 of million cells.

Title: Visualizing One Billion Cell Simulation Models on an Engineering Desktop with Tecplot 360
Date: Thursday, October 10, 2013
Time: 9:00 AM – 10:00 AM PDT
REGISTER NOW

Tecplot’s VP of Product Development, Dr. Durrell Ritterberg, will be attending the fourth bi-annual Metacomp Symposium from Sept. 17—Sept. 19 at the Sheraton Hotel in Unversal City, California, near Los Angeles.

This highly technical meeting will spotlight the latest advances in CFD and CAE technologies and applications.

If you would like to meet with Durrell during the symposium, please contact him at 425.653.1200, 1.800.763.7005, or email durrellr@tecplot.com.

Click to visit the Metacomp Symposium website >>

Pete Koehler, Tecplot’s IT Manager and Virtualization Architect, is interviewed by Dan Kusnetsky on ZDNet’s Virtually Speaking blog. Pete explains the importance of speeding up automated code compiling systems to support software development and what Tecplot did when storage performance became the bottleneck in the development process.  Read the full interview >>

http://www.pernixdata.com/product/

Understanding Tecplot file types is helpful for getting the most out of your Tecplot Software and for working efficiently. In this Tecplot Tip we define each Tecplot file types and use the Tecplot Macro as an example. 

Tecplot basic file types:

• layout file or *.lay is a file that creates a specified plot (e.g. an XY plot of surface temperature vs. time) and is tied to a specific data set.
• style file or *.sty is a file that creates a specified type of plot (e.g. a “doghouse plot”, but is not tied to a specific data set.
• plt file or *.plt is a file of data in Tecplot’s binary format.
• dat file or *.dat is a file of data in Tecplot’s ASCII format.
• macro file or *.mcr is a file that directs Tecplot to take a given action (e.g. load a *.dat file, and create a standard plot via a chosen *.sty file).

Note that the .sty, .mcr, and .lay files are human readable (and editable) via a simple text editor like Microsoft Notepad.

Example Macro

Below is an example of a Tecplot macro that takes the difference between two variables through a range of zones.

#!MC 1000
 #
 # First must create T_del variable for all zones #
 $!AlterData Equation = "{T_del} = 0"
 #
 # Loop over the base set of zones. Deposit the delta into T_del for the base set of zones only. If you to assign T_del to
 # the difference in BOTH sets of zones change "$!AlterData [|Loop|]" to be "$!AlterData [|Loop|,|OtherZone|]"
 #
 $!Varset |BaseNumZones| = (|NumZones|/2) $!Loop |BaseNumZones|
 $!VarSet |OtherZone| = (|Loop|+|BaseNumZones|)
 $!AlterData [|Loop|] Equation = "{T_del} = {T ,K}[|Loop|] - {T ,K}[|OtherZone|]"
 $!EndLoop

This macro could be named diff.mcr, and then run from the Tecplot menu Scripting >> Play Macro/Script.

Alternately, the macro could be put inside of another macro function. To do this, copy the macro below into the tecplot.mcr file found in the Tecplot root directory. (It’s the same as the above macro minus the #!MC 1000 line)

!MacroFunction Name = “Calculate Difference”
 #
 # First must create T_del variable for all zones #
 $!AlterData Equation = "{T_del} = 0"
 #
 # Loop over the base set of zones. Deposit the delta into T_del for the base set of zones only. If you to assign T_del to
 # the difference in BOTH sets of zones change "$!AlterData [|Loop|]" to be "$!AlterData [|Loop|,|OtherZone|]"
 #
 $!Varset |BaseNumZones| = (|NumZones|/2) $!Loop |BaseNumZones|
 $!VarSet |OtherZone| = (|Loop|+|BaseNumZones|)
 $!AlterData [|Loop|] Equation = "{T_del} = {T ,K}[|Loop|] - {T ,K}[|OtherZone|]"
 $!EndLoop
$!EndMacroFunction

Run this macro from Tecplot’s quick macro panel Scripting >> Quick Macros, and click on the Calculate Difference button in the menu.

To find out how Tecplot can customize your application, contact us at sales@tecplot.com, or use the online Contact Form.

Long time Tecplot customer, Frank Muldoon, and his colleague, Hendrick Kuhlman, at the Vienna University of Technology, received the “Best Picture in Physical Science award” for this image of Invariant Streamtubes of a Hydrothermal Wave in a Thermocapillary Liquid Bridge.
Congratulations to you both!

Invariant Streamtubes of a Hydrothermal Wave in a Thermocapillary Liquid Bridge

Abstract

In microgravity, large-size cylindrical liquid bridges can be established, because they do not break. Differential heating of the support disks creates a thermocapillary flow which is a gravity-independent driving mechanism. Typically, the flow becomes three-dimensional and a rotating hydrothermal wave arises. Surprisingly, there exist regions in this complicated three-dimensional flow such that fluid from one region does not mix with fluid from another region. The image shows an axial view of several of these regions, obtained numerically, which arise in closed tori and which rotate with the same azimuthal velocity as the hydrothermal wave.

Award

Authors and affiliation: F. H. Muldoon and H. C. Kuhlmann (Vienna University of Technology), E-mail: h.kuhlmann@tuwien.ac.at

Frank Muldoon

Frank Muldoon has certainly taken Tecplot through its paces—over the years, he has carefully documented more than 70 issues! Congratulations again on the Award, and thank you from all of us here at Tecplot for your 15 years of support.

“Thanks for all your help with getting the best out of Tecplot!”
—Frank Muldoon

Understanding Tecplot usage trends has been important for customers and prospects especially to help them justify new license purchases. The tools currently available on the market can be expensive and often have more features than needed to report usage trends.

Last weekend, I finally finished a new tool I’ve been working on (and off) since March. This tool accurately reads RLM usage log files. The RLM Log Reader tool will generate reports for each RLM usage log type.

• The report log contains the most data, but is not enabled by default. Customers are encouraged to turn it on manually. The next Tecplot RLM release may see the report log default to on, but until then, here’s how you can turn it on: Turn on RLM report log.
• The ISV usage log, teclmd.log, is turned on by default when installing RLM using the Tecplot installer (available from our Software Downloads website page).

Documentation is included with the tool that further explains how to use it. Sample logs are also included for you to try it out.

This was an interesting hobby project that taught me some new aspects about programming. I hope you will find it useful. Here is a link to the tool: http://sourceforge.net/projects/rlmlogreader/

This Tecplot Tip was written by Steve Robinson, Software Development Engineer at Tecplot, Inc.

By Dr. Durrell Rittenberg, Vice President of Product Management

Over the last decade, I have followed several technological advancements in numerical simulation post-processing. While there were improvements in the area of parallel rendering and client-server technology, these approaches were limited to those with large computational resources. The most notable breakthroughs available to most engineers came in the form of improved graphics cards – thanks in large part to the gaming community. Today, a majority of the engineering community uses a workstation for CFD post-processing visualization.

In 2008, Tecplot introduced “Load-On-Demand” technology which allowed users to load only the variables needed during their visual analysis. This significantly reduced the memory footprint for large data analysis. However, for a very large solution where loading a single variable into memory was not possible, performance suffered. Subsequently, a new approach was needed to support the requirements of the CFD community looking at very large computational meshes.

New Technology Solves Very Large Data Demand

Researchers at Tecplot have been working on new technology that would enable engineers to post-process very large data solutions on engineering workstations, desktop computers, or laptops. After almost 24 months of research and development, one of the key issues – that of memory usage – has been overcome. Tecplot now has a working Beta version of this new technology.

Tecplot Working Beta with New Technology

Early results are promising. Internal tests have shown improvements on the order of 40 to 100 times faster than Tecplot 360 2013 R1 for common post-processing tasks. The increase in speed is very exciting, but perhaps more exciting is the decrease in memory usage.

This morning I loaded a one billion cell model on my laptop and never used over 8GB of RAM. Loading this same data into Tecplot 360 2013 R1, by comparison, required close to 60 GB of RAM!

Join us for a Webinar on Oct 10

Tecplot’s Chief Technical Officer, Dr. Scott Imlay, and I invite you to join us as we demonstrate this new technology, and discuss the next generation of Tecplot 360 products.

The Significance of This Research

According to the National Institute of Deafness and Other Communications Disorders (NIDCD), voice dysfunction affects approximately 7.5 million people in the U.S. every year.² Educators have a high incidence of voice dysfunction, and others who are commonly affected include doctors, nurses, attorneys, performers, and salespeople. Typically these problems result from vocal fold (VF) paralysis of one (most common) or both (a more rare condition) of the vocal folds due to overuse of the voice.

Additional causes for voice dysfunction include physical trauma to the larynx, viral infections, neurological diseases, cancers, inflammation and nodules or growths on the vocal folds. Symptoms of vocal fold paralysis can be distressful and disruptive to daily life, and may include hoarseness, difficulty breathing, choking when eating, coughing, and shortness of breath, among others.

Challenges in Studying Human Phonation and Voice

Human phonation and voice are unique to each individual. Voice is how we inform, persuade, inspire, express ourselves, and connect with others. When there is damage to the mechanics of the human voice, disruption in other areas of life can ensue, including the ability to continue working and flourish in social situations.

Figure 1. Structures involved in speech and voice production. http://www.nidcd.nih.gov/health/voice/pages/vocalparal.aspx

Upon breathing, the vocal folds open, and upon swallowing, they close. The ability to speak results from the interaction of aerodynamic forces, fluid dynamics and structure of the vocal folds, which vibrate as they allow air to pass through, resulting in speech.

The study of human phonation and voice is challenging, as the larynx and vocal folds are difficult to visualize and access. Studies of excised canine larynxes provide useful information but have their limitations. Physical models created of various substances can mimic the complex tissue layers, and aerodynamics and physical structure of the larynx and surrounding structures. However, it is difficult to translate data from these models to actual conditions of human physiology. Computational modeling has the potential to model phonation problems with all their complexities.³

Current Treatment of Vocal Disorders

Many vocal problems resolve within a year, with intervention by otolaryngologists (physicians and surgeons specializing in conditions of the head and neck) and speech-language pathologists, who can help patients with exercises and improved breathing techniques to make the voice stronger. If symptoms do not improve within a year, surgery may be the next option.

One surgical procedure involves insertion of an implant into the patient’s paralyzed vocal fold in order to hold the vocal fold in proper position. “This is a very uncomfortable procedure for the patient,” Zheng said. “It is performed in the operating room using only local anesthesia, as the surgeon wants to ensure the implant is in the proper position and the patient can speak.”

The NIDCD reports that it is common for these implants to require repositioning in an additional surgery in up to 25 percent of cases.⁴ This results in more discomfort for the patient as well as increased healthcare costs.

Steps to Discovery with Tecplot 360

The research of Zheng and his colleagues has the potential to alleviate the drawbacks of today’s treatment of vocal disorders. Tecplot 360 is the only visualization tool that he and his colleagues use to perform patient-specific modeling of human phonation and speech. Their ultimate goal is that one day, three-dimensional, computational flow dynamics modeling will enable scientists and surgeons to predict the proper size and configuration of vocal implants, making anesthetized surgery possible for patients, with fewer repeat surgeries required. Zheng highlighted that there are three phases to visualizing the model and the result.

• Phase 1: Researchers reconstruct a patient-specific model from the patient’s CT (computerized tomography) scan and then put the model into Tecplot 360 to check mesh quality.
• Phase 2: Researchers conduct numerical simulations to replicate the process of voice production. They then visualize the results using Tecplot 360, analyze intermediate results, and further debug the cases.
• Phase 3: Researchers analyze all results from the simulation and again use Tecplot 360 to create illustrations and animations for use in published journals and presentations.

The Power of Tecplot 360

Tecplot enables us to view the 3D vortex structure, the glottal jet flow and the movement of the glottis. The animation shows the iso-surface of swirl strength of the glottal airflow, the corresponding vibration pattern of the glottis, and the time history of flow rate in a patient-specific, computational model of the human larynx. These observations greatly enhance our understanding of the fundamental mechanism of voice production.

The Future

Although research data is very promising to date, Zheng notes that several more steps in the research process are required before a clinical trial can be conducted.

Notes

1. Xudong Zheng, assistant professor in the Department of Mechanical Engineering at the University of Maine, is working with his colleagues, Dr. Qian Xue from the University of Maine, Dr. Rajat Mittal from the Johns Hopkins University, and Dr. Steven Bielamowicz (MD) from the George Washington University Hospital to more fully understand the impact of fluid dynamics and the complex physics of human phonation and speech. Zheng received his Ph.D. in May of 2009 in Fluid Mechanics, Thermal Science and Energy, from The George Washington University in Washington, D.C. where his dissertation focused on the biomechanical modeling of vocal fold vibration and glottal flow aerodynamics during phonation. Previous studies included obtaining an M.S. degree in Aerospace Engineering from The Academy of China Aerospace Science, Beijing, China, and a B. S. in thermal power engineering at the Beijing University of Aeronautics and Astronautics.[/pl_alertbox]

2. NIDCD website: www.nidcd.nih.gov/health/statistics/vsl/Pages/stats.aspx, accessed 09/25/2013

3. Rajat Mittal, Byron D. Erath, and Michael W. Plesniak. Fluid Dynamics of Human Phonation and Speech. The Annual Review of Fluid Mechanics. 2013. 45: 437–67.  fluid.annualreviews.org

4. NIDCD website: www.nidcd.nih.gov/health/voice/pages/vocalparal.aspx, accessed 09/25/2013

Traditionally, MRI has been used to measure flow properties in “in vivo” applications. At Stanford, the group led by John Eaton has pioneered the use of MRI to measure 3D velocity (MRV) and 3D concentration (MRC) in engineering flows. Coletti, a postdoctoral fellow in Eaton’s lab, has been using and advancing this method in various applications.

Coletti is investigating transport and mixing in complex flows and turbulent flows. Because he deals with millions of experimental data points, visualizing large 3D data sets is critical to understanding the dynamics of the flows he studies. Coletti uses Tecplot 360 to visualize his results and to communicate his findings to others.

One example is the dispersion of a contaminant injected into a crossflow. In this case, Coletti collaborated with Honeywell to understand the flow physics of film cooling for gas turbine airfoils.

Video 1 shows isosurfaces of time-averaged concentration of a contaminant injected into the turbulent cross-flow. The animation displays decreasing concentration levels, which extend further downstream as the contaminant gets diluted by the crossflow.

Figure 1. Isosurface at 2.5% of concentration demonstrates how the random structure of the fin contributes to the spreading of the contaminant.

A third example is the inspiratory flow in human airways. The X-ray scan of a subject was used to fabricate a 3D model by stereolithography which replicates the patient anatomy from the mouth to the eighth generation of bronchial branching. Figure 2 shows various sections of the flow field, at the first bifurcation, and at further generations. In-plane velocity vectors (superimposed onto color contours of flow speed) demonstrate that strong recirculation of the inspiratory flow persists deep down into the bronchial tree.

Figure 2. Various sections of the flow field, in the first bifurcation, and at various stations at further generations.

Lately I’ve been struggling with the visualization version of the classic causality dilemma, and I finally have an answer! But first, a little background.

As many of you know, we have been working hard on a new technology—called subzone load-on-demand—that minimizes the amount of data loaded by Tecplot 360. The basic idea is to divide a large dataset into small pieces, or subzones, and load only those subzones needed for the desired plot.

For example, to make an isosurface of pressure for a large dataset, like the NASA trapezoidal wing shown in figure 1, only the subzones with a pressure range (p_min,p_max) that contain the desired isosurface value of pressure will be loaded. To generate the isosurface shown in figure 2, only 1.5% of the subzones need to be loaded. This makes isosurface generation in the new version of Tecplot 360, Tecplot 360 EX, orders of magnitude faster than previous versions (and faster than competitor codes) that load pressure, for the majority of the data points in the dataset.

Figure 1. NASA Trapezoidal Wing (High-Lift Prediction Workshop) Geometry

Figure 2. Pressure isosurface for NASA Trapezoidal Wing

But, you ask, what if pressure isn’t stored in the dataset? What if only the conservative variables (ρ, ρυ, ρu, ρω, Ε) are stored? This is a common scenario in PLOT3D format files generated by codes like Overflow. This is the classic “chicken or the egg” scenario. Ranges of pressure for each subzone (the egg) determine which subzones to load, but pressure (the chicken) doesn’t exist in the file.

For ideal gases, pressure can be computed from the conservative variables using the following formula:

One solution would be to load all five conservative variables, compute pressure at every point in the dataset, compute the pressure ranges, and proceed as before. Unfortunately, this would end up loading all the data—violating the subzone load-on-demand goal to minimize the amount of data loaded. It’s the chicken or the egg; the “Kobayashi Maru”; the no-win situation. Or is it?

It turns out that interval arithmetic can be used to compute bounds for the range of the pressure in each subzone without actually computing the pressure in the subzones.  Interval arithmetic allows you to estimate the range (actually bounds of the range) of the computed variable from the ranges of the input variables and the equation to be computed. With subzone load-on-demand, interval arithmetic is used to determine which subzones to load and only the new variable in the loaded subzones is computed. However, because interval arithmetic will overestimate the ranges of the computed variable for each subzone, it is possible that many unneeded subzones will also be loaded.

We used the NASA Trapezoidal Wing case (figure 1) to test the impact of this approximation when computing, on demand, the pressure from the conservative variables. We also pre-computed a new pressure variable so that we could compare the number of subzones loaded.

The Trapezoidal Wing dataset contains a total of 800,606 cell subzones. Using the pre-computed pressure directly, subzone load-on-demand loads 11,905 subzones (1.49% of the total). Using interval arithmetic with the ranges of (ρ, ρυ, ρu, ρω, Ε), subzone load-on-demand will load 13,349 subzones (1.67% of the total). That is only 12% more subzones than were loaded with the pre-computed pressure.

So, you don’t need the chicken, the egg can come first!

You are invited to participate in the Tecplot 360 Beta Program.

Join over one hundred of your colleagues who are using the Beta to quickly and efficiently load and analyze simulation results. Early benchmarks show a significant performance increase on very large files—using an 8 GB desktop workstation!

Join the Beta Program

Last month, I attended the IEEE Visualization Conference in Atlanta. The Vis conference is the premier forum where researchers and academics in the fields of scientific visualization, information visualization, and visual analytics present their latest and greatest ideas. This year Durrell Rittenberg (Vice President of Product Management) joined me on the cross-country trek.

I’ve been attending the Vis Conference off-and-on since 2000—it helps me make sure Tecplot is aware of the newest techniques and trends in visualization research. Many clever ideas are presented each year, but most are not really applicable to our products—either because they don’t solve the problems our customers face or don’t add enough value to warrant the additional complexity they bring, or the ideas are just trendy and oversold.

On the flip side, some ideas are priceless gems that can improve the capability and usability of Tecplot software. Our grid coarsening techniques (decimation) were derived from ideas presented at the 2001 Vis conference in San Diego, and many subzone load-on-demand techniques can be traced back to out-of-core techniques presented at the 2005 Vis conference in Seattle.

This year, I did hear a couple of interesting themes (and thankfully, no “trendy” ideas). The rest of this blog is about one of the gems.

Theme:  Visualization software architectures must evolve to keep pace with changes in computing hardware.

This won’t be a surprise to those who have been reading our blogs or have attended our webinars. In fact, Tecplot has been aggressively responding to the changing hardware landscape for the last two years. Three primary drivers of the change are:

1. Computing performance is improving much faster than I/O performance. In other words, it is taking more and more time to read or write the data we are capable of creating with high-performance computer (HPC) systems. The industry is responding to this in a variety of ways – from not writing the data at all (in Situ visualization) to faster storage systems and file formats (like exaHDF5).  Tecplot is responding to this change with subzone load-on-demand, a technology that allows our software to read only the data needed to perform the desired analysis or visualization.
2. The number of cores per CPU or GPU is growing rapidly. This has huge ramifications for software that uses the message-passing-interface (MPI) to parallelize computations. As the number of cores increase, MPI becomes less efficient. In fact, Kenneth Moreland (a panelist in the “Challenges for Scientific Visualization Software” session) said that MPI is simply not usable for GPU-based computing. The solution is to use threading in combination with MPI. Fortunately, Tecplot is primarily parallelized through threading so we are not impacted as much as some other software packages.
3. Memory per thread is declining. Memory for each CPU/GPU combination is actually increasing, but the number of threads required to efficiently utilize CPU’s or GPU’s is increasing faster than memory. This has major ramifications for in Situ visualization—a common idea for circumventing the first driver. Any memory utilized for visualization is memory that cannot be utilized for the simulation software. Existing visualization software tends to take too much memory for in Situ visualization on HPC systems.

To summarize, visualization products struggle to keep pace with changes in computing hardware,
but software packages that depend on massively parallel systems to visualize large data files are
affected the most.

Learn more about Tecplot’s large data solution.

Watch this webinar Durrell and I recently recorded:
Visualizing One Billion Cell Simulation Models on an Engineering Desktop with Tecplot 360.

Join us for a Webinar on December 5

Space is limited.
Reserve your Webinar seat now at:
https://www1.gotomeeting.com/register/866758809

Evaluating multiple designs to determine the optimal configuration is part and parcel to modern engineering. In this Webinar you will learn how Tecplot Chorus and CFD++ can be leveraged to address operational difficulties caused by deposits inside pelletized furnaces.

After the conversion from liquid fuel oil to natural gas, combustion chambers can experience a significant increase in the deposit accretion rate due to over-deflected flames. We will describe how these deposits were reduced by using analytical methods supported by a computational fluid dynamics (CFD) tool to develop a novel burner.

In this webinar we will discuss:

• The computational strategies used with CFD++
• Evaluation of the design space with Tecplot Chorus
• Results and conclusions from the studies

This is a joint Webinar between Tecplot, Inc. and ATS4i.

Thanks to those who joined us for the Webinar on March 6
View the recording >>

You already know the challenge of working with large simulations results. Last year, we set a goal to enable engineers to quickly visualize one billion cells on a typical engineering workstation.

We have met this goal by using subzone load-on-demand technology. The majority of performance gains, however, depend on using a subzone-loadable file format (SZL).

This Webinar will show you practical strategies for generating SZL files, using a Tecplot export, and using the Tecplot I/O library, TecIO.

Hosting the Webinars are Tecplot experts: Dr. Scott Imlay, Chief Technical Officer; Dr. David Taflin, Sr. Software Development Engineer; and Dr. Durrell Rittenberg, VP of Product Management.

Read more about Tecplot 360 EX on our Preview Page >>

Join over 200 of your colleagues and try Tecplot 360 EX for yourself:
Become a Beta Tester >>

Join us for a Webinar on April 10

The next major release of Tecplot 360 is right around the corner. We have made major improvements in both usability and performance, including the ability to:

• Load CFD solutions with data too large for existing memory
• Process workflows up to 100 times faster
• Work more efficiently using right clickable context menus
• Compare numerical models with test data in the same window

In this webinar, Dr. Durrell Rittenberg, VP of Product Management, and Dr. Scott Imlay, Chief Technical Officer, will walk through two use cases that highlight the benefits of using Tecplot 360 EX over earlier versions:

• Case 1: External aerodynamics of a UAV
• Case 2: Evaluation of a CFD solution where data is too large to fit in memory

There will be plenty of time for questions throughout the Webinar. If you have questions now, let us know on the registration form so that we can be sure to get them answered.

Space is limited
Reserve your Webinar seat now at:
https://www1.gotomeeting.com/register/480104616

Try Tecplot 360 EX for free

We invite you to try Tecplot 360 EX before this Webinar by joining our Beta program >>
You can also watch these short Tecplot 360 EX videos >>

Join us for the Webinar on June 12

Space is limited.
Reserve your Webinar seat now at:
https://www1.gotomeeting.com/register/200417353

How to speed up CAE design decisions

High fidelity simulation methods are being used throughout the design process to analyze modern engineering problems. The availability of high performance computing (HPC) resources has led to an exponential growth in data size. The ability to effectively analyze your largest simulation is a key to speeding up engineering decisions. Modern CFD post-processing software needs to allow you to quickly and accurately analyze all your simulations.

This Webinar will give you insights into how Tecplot 360 EX can improve your engineering decision-making by:

1. Automating engineering analysis
2. Loading and analyzing large CAE models
3. Creating PowerPoint-like presentation reports
4. Comparing multiple data sets from heterogeneous data sources

The resources below have more detailed information about Tecplot 360 EX and the technologies that enable these major performance and usability improvements.

• Short videos demonstrate style control, slice design, and report layouts.
• Recent Tecplot 360 white papers explain how subzone load-on-demand technology improves performance.
• Recorded webinars extend the discussion of Tecplot 360 EX showing you everything you need to know.

Contact Us

Please contact us if you have any questions. Call 425-653-1200 or 1-800-763-7005, or email sales@tecplot.com. We appreciate your interest and look forward to hearing from you.