Tuesday, December 25, 2012

Random thoughts (about CFD, etc) on the Christmas Day of 2012

Merry Christmas!

It has been quite an eventful year with my recent job change from Iowa State University (ISU) to the University of Kansas (KU). Many of my colleagues and friends were very surprised (or even shocked) that I would even consider moving to the "dark side" (by being the chairperson of an academic department). I fully agree that something like this would have been unfathomable only two years ago. I have always enjoyed research and teaching as a college professor, and would have been extremely happy doing both for the rest of my life. The person who was the most responsible for this change was Dr. Rich Wlezien, my previous boss and the Vance and Arlene Coffman Endowed Department Chair in Aerospace Engineering at ISU. Rich tapped me to be his Associate Chair for Research and the Director of Graduate Education (or DOGE at ISU) around late 2010. Since I did not volunteer for the position, I agreed to give it a try to see whether the job would distract me from my regular research and teaching. Serving in this role revealed to me a bigger picture of the Department than what I would normally see. With the Graduate Studies Committee, we were able to reform the graduate program in several areas. Earlier, these reforms had been considered beneficial to the entire Department, but not pushed through due to resistance from multiple directions. With extensive discussions and consensus building, the reformed graduate policies received nearly unanimous faculty support. Events like this showed me that a positive impact can be made to an academic environment not only through teaching and research, but also through service, including being a Department administrator. Another person who was also responsible for the change was Dr. Charlie Zheng, my fellow CFDer and colleague at KU, who convinced me to take a look at the opportunity. A heartfelt thank you to both Rich and Charlie.

I have found that both ISU and KU are great places to work. Both aerospace programs are nationally ranked, and have produced very prominent national leaders such as Thornton "T" A. Wilson (ISU alum and former CEO and Chairman of the Board of Boeing), Vance Coffman (ISU alum and former CEO and Chairman of the Board of Lockheed Martin), and Alan Mulally (KU alum and current CEO of Ford). ISU has been known for its CFD program since the 1980s, and its faculty (Tannehill, Pleacher and Anderson) authored one of the most popular CFD text books. ISU has a much larger faculty, has graduated much more students, and ranks higher than KU. KU is known internationally for its aircraft and engine design education. Over the years, KU students have won many AIAA student aircraft and engine design competitions, ranking KU near the top (if not at the top) of all international aerospace programs. KUAE is poised to grow rapidly in the next few years due to the University's strategic plan to grow the engineering faculty by 30% and the number of students by 50%. I hope to strengthen KUAE's research profile so that it will one day rank as high as ISU. Although we loved living in Ames, Lawrence does have the better climate, downtown and variety of restaurants!

I heard a rumor that I changed job because CFD is dead, or my research has hit a big obstacle. I can forcefully state that neither is true. In fact, I intend to continue my CFD research and education in the foreseeable future. I brought nearly my entire group from ISU to KU, and we are working very hard on tackling some of the challenges in high-order adaptive CFD methods (see my previous blog for sample topics). Now and then, we look for talented and hard-working students or postdocs to join our team. If you are motivated and enjoy math, programming and fluid dynamics, you are welcome to apply to KUAE. On CFD education, we are considering to establish a graduate CFD certificate at KUAE, hopefully in the Fall 2013. Do visit KUAE (http://www.ae.engr.ku.edu/) often for updates.

After more than three decades of development, CFD has undoubtedly established itself as a critical tool in the design process of many industries. I am not sure of the market size of commercial CFD software products, but won't be surprised if it is in the order of billions of dollars/year. Constant improvements have been made to these products, which are increasingly more efficient, accurate, robust, and easier to use. There are also many web sites and blogs dedicated to CFD. The fact that these sites and blogs are being visited is a good sign that CFD is well and receiving a lot of attention. I particularly like "Another Fine Mesh", maintained by John Chawner of Pointwise. I just wonder how John manages to run his company and still find time to do the blogs on a weekly basis. 

Almost all CFD commercial software has benefited from research carried out in the "golden age" of CFD, generally considered to be the 1980es, by many well-known CFDers. If we do a survey about the top CFD giants in the world, who have made the most far-reaching impact, I am very confident that the names of Antony Jameson, Phil Roe and Bram van Leer would stand out. In order to celebrate their seminal contrbutions in CFD, an international symposium in their honor is being organized, with support from AFOSR. More information will be posted in the near future with a link from this blog.

BTW, the 2nd International Workshop on High-Order CFD Methods will be held in Germany. See this web site for more info: http://www.dlr.de/as/desktopdefault.aspx/tabid-8170/13999_read-35550/   

Finally, what happened to the often dreamed "push button" CFD tool, which is supposed to give you accurate CFD solutions by pushing a few buttons? Is such a tool going to appear one day, or is it still desired? Let me know your thoughts.

Last but not least, have a great 2013!


  1. ZJ - Congratulations on the new position. As someone who serves on an AE/ME department advisory board I can appreciate what you wrote about advancing the mission of the department through service in addition to teaching and research. And your plans for a graduate CFD certificate sound great. I'd love to come visit KU some day.

    As for "push button" CFD I always fall back to Fred Brooks' book on software engineering in which he states that automatic has always meant "better than we're currently doing." In that regard, progress is made every day. The other issue is the changing complexity of problems. Go back 10-20 years, look at the problems we were studying then, and I'm pretty certain we could do them today with a push of a button.

    Best Regards. Hope to see you at Aerospace Sciences in a couple of weeks. And thanks for the kind words about Another Fine Mesh. If you ask my coworkers, they'll wonder when I'm actually going to do real work instead of blogging all the time.

    1. Thanks, John. We would love to have you visit KUAE some time. Lawrence is a great town, if you have not visited before.

      I agree with your comments regarding "push button" CFD. I think a key missing piece in the puzzle is robust error estimators for current CFD solvers.

      Yes, I hope to catch you in the ASM meeting, and I look forward to reading more of your thoughtful blogs.

      Best regards,

  2. Hi ZJ,

    I'm glad to see you highly motivated and working actively in KU.

    I have a strong feeling that CFD is not dead.
    I constantly receive messages from all over the world through my CFD websites.
    I often need pushes of various buttons or even new buttons for getting a solution.
    Also, I have ideas for improving current CFD algorithms.

    Have a nice holiday,

    1. Hi Hiro,

      Nice to hear from you and I do agree that CFD still has a lot to be developed and discovered. Keep up the nice work! Hope to see you in Dallas.

      Happy Holidays!

  3. Dear ZJ,

    Congrats on your shift to KU and I am glad to know that you are enjoying the change.

    I find your blog post illuminating and share your wonder regarding how John effectively balances writing such a fantastic blog, Every week , with other work !

    Further along the direction indicated by John, I think most CFD software companies are heading towards push-button, 'quick' CFD. It also seems that such customised tools for specific companies/work-flows are much desired in the industry. It does complicate things from a qualitative perspective, but then, I suppose few things are straight-forward.

    Push-button CFD is however, a great tool for academic purposes. Eg : http://www.zeusnumerix.com/products/cfd/zntutor_cfd

    Hiro's comments are encouraging, and I hope I can get to see and play atleast a minuscule part of another golden era in CFD and the way it is applied!

    It does feel that, though drastic changes/developments in code have slowed down, there are still plenty of applications where CFD is yet to be regularly and rigorously used, especially in sectors like the small scale industry.

    Best Regards and Wish you an exciting 2013,

    1. Hi Shreyas,

      Wish you a very Happy and Successful 2013.

  4. Hi Prof. Wang,

    I ran into your research and your blog recently and found them very interesting. As a former aerospace engineer who has run numerous CFD jobs and experienced the limitations of various codes, I agree that CFD is certainly not dead. I'm currently working at a small company called Rescale (http://www.rescale.com), and we are trying to develop "push-button large-scale simulation". I'll send you a quick e-mail explaining our technology if you're interested.

    S Mani

  5. Prof. Wang,

    Congrats on the new position, ISU's loss is KU's gain.

    I don't think one can see the continuous stream of CFD research and the economic size of the applied CFD industry and call it "dead," but I'd just describe the field as "mature." The golden age of the 1980s tackled the immediately pressing problems of working out numerical methods for solving the governing equations. Not to say there's no room for improvement in numerical methods for CFD (obviously there is, especially in adaptive high-order methods), but what came out of that era is still the conceptual basis for numerics in 2013.

    What happened to the dream of "push-button" CFD? For all intents, sufficient numerical methods (and codes) already exist to solve a wide range of problems to arbitrary accuracy, given sufficient computational resources, but it still takes an experienced practitioner spending a lot of time on pre- and post-processing.

    I think push-button CFD hasn't happened because of something also holding back research today -- a failure to fully incorporate the parallel advances of the software engineering field. As CFD matured, implementations (from surface definition and mesh gen through to post-proc) necessarily became more complex as improvements appeared. Good novel ideas in academic CFD can take months or years for researchers just to implement because they're bogged down in software complexity ("Continuous Fortran Debugging"). The complexity of general purpose software grew faster than CFD in the same time, to the point that the core of software engineering now is managing complexity. One result is the growth of agile development practices, which allow developers to be far more productive today than they were in the 80s and 90s. In my very limited exposure, those standard practices are rare in CFD research, where we can benefit immensely from them.

  6. Mark,

    Thanks for the message and thoughtful comments. Hope things are going well at Princeton.

    It is fair to say that our expectations for "push-button" CFD keep going up. On the other hand, robust solution-based mesh adaptation is a critical requirement, in which much research is still needed.

  7. Hi, Prof. Wang

    Honestly speaking, I'm totally agreed to your view. I'm applying for a Ph.D. or M.S. degree of Aerospace Engineering in Fall 2014. When I was looking for suitable professors, I found there were little people who did research concerning CFD now. Most of them concentrate on bio-fluid, MEMS and etc. I'm really curious about this. In my opinion, Bio-fluid, MEMS or other similar research is just like 3D-print. It can be "fashionable" for a while. But for the development of aerodynamics or hydrodynamics, it is the basic theoretical, computational, and experimental research that makes sense. I hope there will be opportunities to study under your instructions in the future. Wish you have a good day!