I’m Jeremy Shipman and This Is How I Mesh

I was born in the summer of 1972 during hurricane Agnes on the U.S. Navy Submarine Base in Groton, Connecticut, where my father was based as a Submarine Reactor Operator and my mother was a graduate student in Music at Connecticut College.  My parents tell me that early on, as does every young American boy, I aspired to become a trash truck driver.  But over the years as I grew up in a small town near Hershey, Pennsylvania, I began to be inspired by NASA programs, such as the Space Shuttle and Voyager missions, to someday work in the aerospace field. That calling lead me to study physics at Juniata College, and then to pursue a graduate degree in Mechanical Engineering at The George Washington University.  It was at GWU where I was exposed to numerical modeling, first in coursework, and then culminating in a turbomachinery research project where I learned the art of meshing and the science (art?) of running a CFD code to convergence.

In the fall of 1998 (wow was that 20 years ago?) I began my career as a CFD engineer in earnest when I joined CRAFT Tech, which was at that point a relatively new and growing company developing cutting edge computational techniques to solve many complex problems involving fluid physics.  My very first tasks at CRAFT Tech all those years ago had me learning new meshing skills with the ancient, extremely capable meshing software called Gridgen.  Looking back, it is amazing to ponder how much has changed since then.  When I started, we did our pre and postprocessing on SGI Indigo workstations and backed up our solver code revisions on tar tapes.  Grids of a few million cells were considered huge.  Over the years at CRAFT Tech, I’ve had the opportunity to work on many challenging and exciting computational modeling projects spanning the regimes from underwater, to combusting multi-species flows, to rocket engine turbopumps, to high-altitude hypersonic flight regimes.  Along the way I was fortunate to learn from the many talented experts that make up our CRAFT Tech team.

  • Location: I live in the small town of Perkasie, Bucks County, PA (home of the oldest Christmas tree lighting ceremony in the USA)
  • Current position: Senior Research Scientist, Combustion Research and Flow Technology, Inc. (CRAFT Tech)
  • Current computer: Dell Optiplex 9020 (Intel i7 quad core, 16 GB RAM, AMD Radeon graphics) running Windows 7.
  • One word that best describes how you work: Methodical

What software or tools do you use every day?

At CRAFT Tech we develop a number of CFD software tools – my time is spent predominantly with our unstructured CRUNCH CFD® and structured CRAFT CFD® solvers that we manage revisions with in SVN.  The latest version of Pointwise, of course.  For postprocessing large CFD simulation datasets I use Ensight.  My desktop runs Windows 7, but I also find it handy to have an Ubuntu Linux environment running on a VirtualBox for the best of both OS worlds.  On the Linux side I use vim and PuTTY to connect to our in-house Linux clusters or far-off supercomputers.

What does your workspace look like?

If you look closely you can tell how long I’ve been doing this by the classic “Gridgen Support” mousepad.  This picture is how my desk always looks like.  I did not clean off all the post-its, folders, and scrap paper to make it look better…

What do you see are the biggest challenges facing CFD in the next 5 years?

When I started doing CFD 20+ years ago, practical CFD models were much smaller.  The increasing power of many-core parallel computing resources and improvements in solver capabilities have enabled much larger CFD models today.  Larger models generate much larger amounts of data.  Sifting through this data efficiently to pull out the important results is becoming more and more of a challenge.  Increased computational power has also enabled numerical simulations to tackle problems that span categories of physics: aerodynamics, chemistry, radiation physics, thermodynamics, structural dynamics, etc.  An important challenge for CFD is to move towards multi-physics simulations that can provide fully coupled solutions for these types of applications.

What are you currently working on?

One thing I love about working at CRAFT tech is the opportunity to work on many different and interesting applications.  Over the years I have had the opportunity to contribute to CRAFT Tech projects involving computational modeling of large industrial pumps and turbomachinery, liquid rocket engine components, jet engine exhaust flows, aeroacoustics of aircraft structures, ship airwake turbulence, and helicopter rotor wake flows.  Currently I am working on the goal of incorporating high-fidelity CFD results as part of aircraft flight simulation environments.

What would you say is your meshing specialty?

That is a good question.  I don’t know if I have a specialty per se.  I used to be the go-to guy for hybrid/unstructured meshes for complex geometries in my company, but now there are much more skilled meshers at CRAFT Tech than I.  I do have a vast knowledge of tips and tricks that I have learned over the years for making high-quality CFD grids and I enjoy passing those on to my colleagues.  At the recent Pointwise User Group Meeting my nametag had a ribbon that said “Meshing Guru” on it… does that count?

Any tips for our users?

First of all, take the time and effort to build a high quality grid for your application, as it will pay dividends later in a more robust and efficient CFD solution, along with time savings from not having to go back to fix it later.  Divide and conquer: use blocking and connectors to break up a complex problem into parts that are easier to handle.  For large, complex grids, use layers to create groupings that are easy to turn on and off while you are constructing the grid.  Also, I was once taught by a colleague to not “grid yourself into a corner.”  Take the time to plan out the topology of the grid and identify problem spots at the beginning.

What project are you most proud of and why?

Each of the projects I’ve worked on here at CRAFT Tech over the years has had its own challenges that I am proud of.  But I would say our current efforts in integrating CFD results in flight simulation environments are what I am most proud of.  While we are busy working on the details, validations, and testing, it seems as if soon we will be able to see the results as pilots will have new tools for flight testing and training.

What CFD solver and postprocessor do you use most often?

At CRAFT Tech we develop our own CFD solvers.  I most often use our CRAFT CFD® and CRUNCH CFD® Navier-Stokes CFD solvers.  For post-processing I mostly use Ensight.

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

At the recent AIAA SciTech conference in January, Timothy Weathers of CRAFT Tech presented an interesting paper in the Transport and Thermophysical Properties session titled, “Characterizing Thermodynamic Properties of Pure Components and Binary Mixtures at Rocket Conditions Using Molecular Dynamics.”

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

We usually attend various AIAA, ASME, and AHS conferences throughout the year.  This year I plan to attend the AHS Forum 75 that will be held right here in Philadelphia in May.

What do you do outside the world of CFD?

Outside the world of CFD my wife and two teenage boys keep me busy!  In the past few years, I’ve had the opportunity to go on some adventures with my sons as part of our Boy Scout Troop: we climbed Mt. Katahdin and canoed for five days through the Allagash waterways in Northern Maine.  In 2018 we trekked across the White Mountains including hiking to the top of Mt. Washington in New Hampshire.

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

Don’t ever type \rm -r *

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

I like to judge a restaurant by the quality of their burgers, and the best in this area can be found at our local favorite: The Perk.

About Travis Carrigan

A Pointwise engineer helping other engineers solve their meshing problems.
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