I’m Steve Karman and This Is How I Mesh

Steve Karman, Staff Specialist on the Applied Research Team.

Steve Karman, Staff Specialist on the Applied Research Team.

I’ve only been a Pointwise employee for just over a year, but my history with Pointwise and the staff goes back before the company was formed. I was in the CFD group at General Dynamics when the executive team (John C., John S. and Rick M.) was hired. I was dabbling in structured mesh generation and trying to develop Euler and Navier-Stokes codes at the time. As the Gridgen development proceeded I was simultaneously applying the tools to generate meshes about an F-16 configuration. As such, I am proud to claim the moniker of “Alpha” tester for the early versions of Gridgen.

This was distributed processing in the day. We were located in Fort Worth, TX working on DEC Vax computers in Palo Alto, CA at NASA Ames and displaying graphical results on a Tektronix 4014 terminal which used thermal paper for hard-copy output. The outcome of our efforts resulted in a technical paper presented at an AGARD (Advisory Group for Aerospace Research and Development; an agency of NATO) conference in southern France. We believe this paper was the first publication of a CFD solution for a full aircraft configuration.

As for my background, I received my B.S. & M.E. in Aerospace Engineering at Texas A&M University. I began working at General Dynamics in 1983 and continued with my education part time at the University of Texas at Arlington, receiving my Ph.D. in Aerospace Engineering in 1991. I worked at GD (which became Lockheed and then Lockheed Martin) for 20 years. During my time at GD I became known for the development of SPLITFLOW, a Cartesian-grid Euler/Navier-Stokes code with automatic mesh generation. In 2003 I accepted a research professor position the University of Tennessee at Chattanooga. I performed mesh generation research and taught two graduate level courses in mesh generation. Eventually I became a tenured full professor. In 2014 I decided to leave UTC and was hired by Pointwise to assist with advanced meshing techniques on the Applied Research Team.

  • Location: Fort Worth, TX
  • Current position: Staff Specialist on Applied Research Team
  • Current computer: Apple iMac Workstation: Retina 5K, 27-inch, 4 GHz Intel Core i7, 32 GB 1600 MHz DDR3, AMD Radeon R9 M290X 2048 MB; Apple MacBook Pro (personal laptop): Retina, 15-in, 2.5 GHz Intel Core i7, 16 GB 1600 MHz DDR3, Intel Iris Pro 1536 MB
  • One word that best describes how you work: Relentless

What software or tools do you use every day?

It seems like I always have multiple tabs open in MacVim on my laptop. I mostly compile code on the command line in terminal windows, but occasionally debug in Xcode. Visualizing meshes is a must. I like to view them using FieldView most of the time. I have VisIt and ParaView, but tend to go back to FieldView. And, of course, I also use the version control software P4V by Perforce.

What does your workspace look like?

Steve's current workspace.

Steve’s current workspace.

As you can see I have an affinity for Apple products. I migrated from Windows while at UTC and have no desire to go back. The reason for multiple workstations is because I plan to perform research in parallel mesh generation. The older iMac was being retired and it was offered to me. Couldn’t let a future parallel compute node go to waste!

What are you currently working on?

Just as Chris Fouts mentioned last month, I am working on a new feature that is in support of the U.S. Air Force contract. It will make use of the style of meshing that was used by SPLITFLOW. Once implemented I hope this feature will be further expanded beyond the original intent.

I am also developing prototype code to perform high-order mesh elevation. Finite Element Methods (FEM) are seeing a tremendous increase in the CFD community. These methods have a rigorous mathematical framework and can achieve high orders of accuracy with a compact compute stencil. High order meshes are generally created by adding mid-edge and mid-face nodes to linear elements. The creation of high order meshes for fluid flow analysis is extremely difficult as the viscous layer elements are generally near highly curved boundaries. Simply inserting new nodes into the elements leads to invalid meshes. Therefore, some form of mesh curving in interior edges is required. I am exploring the use of an unstructured smoothing scheme I developed to curve these high-order meshes.

The basic mesh smoothing method used in the mesh curving project has already been implemented in another form in Pointwise version 18. There is a new algebraic normal extrusion method (not T-Rex) that I worked on with Mike Remotigue. We published an AIAA paper this past January describing the scheme (AIAA-2016-1671). This helps control the quality of the viscous layer elements during the extrusion process.

What would you say is your meshing specialty?

I would have to say that Cartesian hexahedral meshing is probably my specialty. It is a field I have been involved in since the GD days. The method is highly automated and allows for mesh adaptation. It is a very efficient means of discretizing far-field domains and is extremely fast. Plus, the hierarchical data structures can be used for a variety of purposes, not just for creating Cartesian aligned elements. In fact, there are Octree data storage routines in Pointwise that I contributed several years ago.

Any tips for our users?

I will pass along two pieces of advice that were given to me. Number one is learn how to use the “Layer” manager in Pointwise. It can be a great time saver for big projects. I personally do not work on many big projects, but the ability to manage all the different mesh objects can be very useful. The second tip would be to consider using the scripting language in Pointwise called Glyph. I took the scripting course last year because I knew I would need to know how to write scripts for code development. It is extremely handy to have a script for common repetitive tasks.

What project are you most proud of and why?

I am really excited to see how the work I am contributing on the Air Force contract turns out. I think it will be an extremely useful capability and will lay the ground work for similar meshing capabilities in other parts of the Pointwise product.

I am also excited about the high-order meshing project. I see the use of this branch of CFD analysis increasing rapidly. There is a definite need for robust methods for obtaining these curved meshes. This will also require the methods to be ported to parallel processing environments (I will put that extra iMac to use).

What CFD solver and postprocessor do you use most often?

As mentioned previously, I use FieldView on a daily basis to examine meshes. There is no better debugging tool for mesh generation than the visual inspection of the mesh. I don’t use many CFD solvers in my current work. When needed, though, I tend to use one of the Euler or Navier-Stokes solvers I developed while at UTC.

Are you reading any interesting technical papers we should know about?

Being active in AIAA I am constantly looking at mesh generation papers at conferences and in the AIAA Journal. These have direct relevance to the Aerospace community.  I attend the International Meshing Roundtable (IMR) yearly and often find interesting papers that target a different mesh generation community. It provides an interesting and different perspective on meshing problems.

Do you plan on attending any conferences or workshops this year?

I attended the AIAA SciTech 2016 conference at the beginning of the year in San Diego. I presented the paper mentioned earlier. I serve on the Fluid Dynamics Technical Committee (FD TC) and the TC has several meetings that take place during the conference. I volunteered to help organize the technical sessions for the FD TC for the 2017 SciTech conference to be held in Grapevine, TX.  I am also the liaison from the Fluids TC to the Meshing, Visualization and Computational Environments TC. I plan to attend the Aviation conference in June in Washington, D.C. and plan to attend the International Meshing Roundtable conference in the fall.

What do you do when you’re not generating meshes?

This may seem uncommon for an engineer, but I have been involved in officiating for swimming. I am a nationally certified USA Swimming official. This is the organization that manages club swimming for the U.S. This is also the organization that officiates for the U.S. Olympic Trials (no I have not officiated at the trials). I have officiated at club meets, middle school and high school meets and at college meets. I got involved in officiating when my youngest daughter swam and have continued. It turns out that a large percentage of the officials I have worked with on deck are engineers.

What is some of the best CFD advice you’ve ever received?

“Everyone trusts wind tunnel results except for the engineer running the tests. Nobody trusts the CFD results except for the engineer running the codes.”  There is some truth to those statements. Unfortunately, ignorance plays a major role in propagating these myths. In reality neither should be trusted without true validation and calibration. Experimentalists must validate and calibrate their wind tunnel equipment. Likewise, CFD practitioners need to validate and calibrate their codes. And in a strange sense the CFD practitioner needs to be “calibrated”. CFD is not a “black box”. It takes time to develop the knowledge to trust the results obtained with the processes that are followed.

If you had to pick a place to have dinner, where would you go?

I am not known to be too particular about where to eat. Having moved to Tennessee for 13 years I had a longing for two types of food. One is barbeque beef. It is mostly pork in the south. So I frequently treat myself to some Texas barbeque at Dickie’s. And the second is Whataburger.

About Travis Carrigan

A Pointwise engineer helping other engineers solve their meshing problems.
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7 Responses to I’m Steve Karman and This Is How I Mesh

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