I’m Uli Fuchs and This Is How I Mesh

Uli Fuchs of CFD Beratung.

Uli Fuchs of CFD Beratung.

I was born and raised in Ulm, a city located in the federal German state Baden-Württemberg in the Southern part of Germany. Internationally, Ulm is primarily known for its Ulmer Münster (church with the tallest steeple in the world (161.5 m)) and as the birthplace of Albert Einstein.

Around 1979, in the secondary school Hans und Sophie Scholl Gymnasium (Sophie Scholl attended this school from 1932 to 1940), I had my very first contact with a programming language, ATARI Basic. For the whole school we had one Atari computer and our computer sciences class with about 20 people was, because of the limitation in hardware resources, writing a few lines of BASIC coding on paper and getting it directly corrected by the teacher. To be honest, this was not very exciting and not a perfect introduction to programming.

A major influence in me wanting to become an engineer was the Deutsches Museum München. It is a great place to visit and see all the different exhibitions with airplanes, machines, and so on.

I studied Aerospace Engineering at Universität Stuttgart receiving my diploma degree as engineer in 1990. It was while working on my diploma thesis when I had my very first contact with CFD working with Fortran on a university code for MPD thrusters.

After leaving university I took a job in a company with a small CFD group distributing PHOENICS in Germany, Austria and Switzerland. The PHOENICS training courses at our office in Stuttgart were held by the PHOENICS instructor from CHAM (Wimbledon, UK). While working there, once on short notice I suddenly had to hold my first PHOENICS training course – but fortunately only the first of the three days. For the second and third day, Prof. Brian Spalding himself came to Stuttgart to support me and it was a very interesting experience.

Some years later I joined the newly founded AEA Technology GmbH and moved to Rottenburg. The German branch of AEA Technology was purely responsible for sales and support of their block-structured CFD code CFX-4 and at a later date CFX-5. While working with CFX-4, extensive Fortran coding was involved to add all kinds of physical models and boundary conditions. When AEA Technology decided to buy the Canadian company Advanced Scientific Computing (TASCFlow), Nick Wyman and I became colleagues for a short period.

After this merger, two colleagues and I founded CFD Consultants GmbH to provide CFD services. We performed consultancy projects with CFX-4/CFX-5 and Fluent using ICEM-Hexa for meshing. After we repeatedly experienced problems creating meshes of good quality, or meshes at all, we heard of an American mesher called Gridgen, developed by Pointwise, Inc.. Our first impression regarding the user interface was not very exciting, but this changed dramatically after our first project with Gridgen under the great support of Erick Gantt. We were very enthusiastic about Gridgen’s flexibility and most of all its smoothing algorithms. Shortly thereafter, we became distributors of Gridgen in Germany, Austria and Switzerland.

Beginning of 2003 I started my own business, CFD Beratung, and since then I am distributor for Pointwise in Germany, Austria and Switzerland. Over the years my relationship with my colleagues at Pointwise, Inc. evolved both on the business and personal side culminating in the fact that Pointwise is somewhat responsible for my daughter marrying an American and now living in the US.

  • Location: Rottenburg, Germany
  • Current position: Owner, CFD Beratung
  • Current computer: HP desktop 64-bit Intel i7 CPU with 12 GB RAM (Windows 10) and a Dell notebook 64-bit Intel i7 CPU and 8 GB RAM (dual boot: Windows 7 and openSUSE Tumbleweed)
  • One word that best describes how you work: Persistent

What software or tools do you use every day?

  • For emails I use Thunderbird and as web browser I prefer Firefox. I know John Chawner favors another one.
  • Depending on the operating system I’m using: Microsoft Office products (Word, Excel, PowerPoint) under Windows and LibreOffice under openSUSE.
  • I use gVim for Glyph scripting work and of course Pointwise for grid generation. I’m using Gridgen less and less these days.

What does your workspace look like?

Uli's current workspace.

Uli’s current workspace.

In the past, when using OpenFOAM for running tests on created meshes, my notebook was primarily running openSUSE Linux. This changed when I started using the Windows version of Caelus. My notice board has filled up over the years with private stuff I like to be surrounded by.

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

Integration of CFD in multiphysics analyses will continue to become more and more important.

Automated process chains demand a growing level of automation in high quality mesh generation.

With the growing capacities of high performance computing (HPC) both pre- and post-processing have to be set in a position to create/handle bigger and bigger meshes (pre) and to handle the corresponding results (post).

What are you currently working on?

I am working on a meshing project for one of our Pointwise/Gridgen users and in addition to that I am working on test cases in preparation for a Pointwise presentation at a potential customer site. Both projects require multi-block structured meshing.

What would you say is your meshing specialty?

For complex geometries it can be a challenge to come up with possible block-structured topologies. But when it comes to consultancy work, multi-block structured meshing is my specialty.

Any tips for our users?

Do not hesitate to contact your local support team (in Germany, Austria and Switzerland it is me) whenever you have questions or problems while using Pointwise. Very often it is possible to solve such problems faster together than struggling through everything yourself for hours or even days.

Related to my current projects in structured meshing I noticed that it is sometimes better to start from scratch with a block-structured mesh than to trying to adapt an already created block topology to a complicated meshing region that does not match. This often ends in a poor quality mesh in that region. I know it can be a difficult step to bring oneself to delete already created blocks. I sometimes catch myself trying to avoid this step, but very often in the end starting from scratch saves time and leads to a higher quality mesh.

What project are you most proud of and why?

A block-structured meshing project of an extremely complicated geometry many years ago with Gridgen. The project lasted several weeks and there were many situations where I was thinking about giving up. The final mesh consisted of thousands of blocks that had the negative side effect of significantly slowing down Gridgen. For that reason, I decided to split up the mesh into ten separate meshes and to read them all in one after another. This was an exercise of concentration for me to keep track of all the interfaces between the different meshes and not to change them in one mesh and forget to do the same for the adjacent mesh. In the end it worked out and importing the different meshes and exporting the entire mesh without any internal walls at the interfaces between the separate meshes was successful. I was not sure whether I would succeed until the final export of the mesh.

What CFD solver and postprocessor do you use most often?

Until recently, I mainly used OpenFOAM, especially to validate the quality of meshes I created. A converged simpleFOAM run is often a good indication for a good quality mesh. Last year I switched to Caelus, a derivative of OpenFOAM developed by Applied CCM. My first motivation to switch was the support of a reliable Windows version. For postprocessing I use ParaView.

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

If you are interested in wind energy applications there are several interesting articles on the website of eawe (European Academy of Wind Energy). Several downloadable papers can be found there. As a general overview of the different aspects and current and future challenges, I like the article of Gijs van Kuik et al. with the title ‘Long-term research challenges in wind energy – a research agenda by the European Academy of Wind Energy’.

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

A few weeks ago I was attending the Fourth Symposium on OpenFOAM in Wind Energy in Delft, The Netherlands. In September I plan to attend the Pointwise User Group Meeting in Fort Worth, TX. In October I may attend the 4th Annual OpenFOAM User Conference 2016 in Cologne, Germany.

What do you do outside the world of CFD?

For years my main hobby was coaching Rottenburg’s men’s handball team. This year, at the end of April, I took a break from handball and plan to start exercising again – something I have neglected lately.

Reading fiction and non-fiction books has always been an interest of mine, as well as listening to music. For the past few years during the summer, friends and I go to Rock of Ages, an open air rock festival in Rottenburg-Seebronn. It is a lot of fun listening to some of these old bands.

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

The quality of the meshes created for many CFD simulations have a crucial influence on the accuracy of your CFD results.

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

When in Rottenburg I would recommend trying local Swabian food for dinner at Gaststätte Hirsch and afterwards head over to Ehgner Eck for a Hefeweizen or any other drink you prefer. We also have an American Diner & Sportsbar called FBI in Rottenburg if you’re interested. Tübingen, the neighboring town of Rottenburg, with its university founded in 1477 and more than 28,000 students, offers a variety of international food. When I am visiting my home town of Ulm I prefer to have dinner in one of the many small restaurants in the historic ‘Fischerviertel’.

About Travis Carrigan

A Pointwise engineer helping other engineers solve their meshing problems.
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