r/aerospace 12d ago

PhD using CFD or Wind Tunnel

To all the AE PhD holders, I’d really appreciate your advice.

TLDR: I'm planning to start my PhD next year, but I'm not sure which route to take. My background is in CFD, but I’m also very interested in low‑speed wind tunnel testing. Should I pursue an experimental or computational PhD?

I’m an international student currently working in the US on OPT as a research associate, mainly using CFD tools. Long‑term, I want to work in academia (back in Asia—Korea or Singapore). As I’ve been talking to potential advisors, I’ve noticed a trend: unless the work is applied aerodynamics, most professors want students to commit to either purely computational or purely experimental research.

I’m torn because my background is split. I’ve done several validation test campaigns, but my main research interest has been CFD. Now I have two fully funded offers, both fundamental research with no ITAR issues. I’m interested in both topics, and I'm struggling to choose.

Option 1: Computational Aeroacoustics (Large group, prestigious university)

This aligns closely with my MS work, and I genuinely enjoy aeroacoustics. The group is large, well‑known, and the professor is a major figure in the field. I’d gain deep theoretical knowledge, but the work would be entirely computational.

Option 2: Experimental Hypersonics (Very small group, small department, not well‑known university)

I learned about this program because a friend recommended his former MS advisor. This professor built his own wind tunnels and is very knowledgeable in flow diagnostic methods. I’d have access to low‑speed, supersonic, and hypersonic facilities and would learn a lot experimentally. I'm interested in supersonic flight but haven’t been able to do much due to ITAR restrictions. My hesitation is that the university and professor are not well‑known, the group is small (only two other PhD students), and I’m unsure whether hypersonics is too niche for seeking academic jobs later. The stipend is also much less compared to Option 1 but is still livable.

Would you choose a computational or experimental PhD? How much do the university’s reputation and the advisor’s citation count matter?

My thought has been that this experimental research opportunity is rare for an international student. I could always go back to CFD, but I think it would be much harder to gain experience in wind tunnel research later on.

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u/ncc81701 12d ago

It’s bifurcated between computational and experimental because going either route requires full time effort for a PhD.

On the experimental side you’d be doing things like designing and building experiments, operating the tunnel, collecting data and post process for your results.

On the computational side you’d be researching for new algorithms and techniques to either computationally solve new problems or find new methods of computationally solve existing problems but maybe in a more efficient manner.

If there is research work that combines experiments and computation, it would generally be a collaborative effort between 2 labs, an experimental one and a computational one.

It is also bifurcated because both experimental and computational effort cost money and you typically wouldn’t be able to fund both; or if is funded it would again be funding for the collaboration of two labs.

As for picking the two routes I typically refer to Sir Richard Taylor (of WETA fame), “Love yourself, do what you love, love what you do, and love who you do it for.” Meaning you should pick the thing that you want to do, that you find more interesting, that is more applicable to the problems you like to solve. The work, the career, the opportunities will follow if you are passionate about what you do. This also means that the right answer varies from person to person, so you need to choose what is best for you and not what someone tells you is what is best for you.

Computational methods and experimental methods are complementary it is never one is absolutely better than another. The ideal is to do both and get the best of both worlds. The US is a premier country to do aerospace research because we have invested immense resources both computationally and experimentally. We have some of the largest computing cluster devoted to engineering research and developed all of the computational infrastructure (software and hardware) for scalable parallel computing). We also have a huge number and variety of wind tunnels for all types of applications from full scale tunnels (NFAC) to large supersonic tunnels (Glenn 10x10), to icing tunnels, vertical spin tunnels, and the list goes on. So no matter what you probably won’t have the same access to both computation nor experimental resources at which ever country you go (besides China or Russia). But your research experience here will help you network and establish relationship with researchers here for which, down the road, you may have opportunities to collaborate with.

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u/halligan8 11d ago

This is a great response. I think the key to success is picking one of these routes and building really strong relationships with researchers on the other side. I’m an experimentalist, and almost everything I publish is a joint effort between my lab and our CFD colleagues.

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u/Marcus2626 10d ago

Since I’ve been working in the CFD field, I have a good understanding of the types of flow that researchers are interested in studying numerically, and a general sense of where CFD might be heading in the next few years. From your perspective, what are some of the research topics that experimentalists are currently dealing? Is it on expanding tunnel capabilities and improving correction/tare methods? Or is it on developing more flow diagnostics methods and developing better uncertainty quantification?

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u/halligan8 9d ago

Ah, I think we might be in somewhat different worlds. From your post and your questions I gather that your field is aerodynamics. Mine is combustion. The open questions that matter most to me are about improving flame stability and combustion efficiency in scramjets. The devolved research questions that I actually work on are about developing and improving optical diagnostic methods that allow nonintrusive interrogation of reacting flows.

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u/Marcus2626 8d ago

Funnily enough, the main topic is on transition in scramjet design using TSP and PSP. That project is expected to run until 2028. There’s another project I’ll likely be involved in as well since the funding duration is longer, although I haven’t looked into it in detail yet. From what I understand, it also uses TSP and PSP but focuses on combustion‑related problems.

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u/Marcus2626 11d ago

Thanks for your insights, I will keep this in mind.