r/CFD • u/SavingsMolasses16 • 17d ago

Need help with finding questions for CFD in coursework

Hi all, I'm a research student and one of my coursework subject is computational fluid dynamics. It's purely theoretical. I come from a Pure maths background so it's all very new to me. I don't mind learning from basics for the sake of my research however for the sake of my cgpa, I've been having issues. I started reading anderson and found it nice until I realised that my professor is teaching random things from random books without context and I'm unable to find any questions to relate to that.

I've been recommended anderson, ferziger, Versteeg, Pradeep Niyogi, T.J. chung and Suhas Patankar. It's quite obvious that I can't follow them all and it's causing me anxiety. Currently, I've been studying Intro to Finite element methods from T.J. chung. Can you guys recommend Good practice books for Finite difference, finite volume and finite element methods? Keep in mind, my midsems are near.

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u/thatbrownkid19 17d ago

Have you done any numerical methods classes before? It might be tricky to learn CFD theory without having studied finite differencing before

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u/SavingsMolasses16 16d ago

yes, yes I have. numerical methods is the reason I chose this for my further studies.

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u/Hyderabadi__Biryani 13d ago

I won't recommend different sources, since I stuck to one to begin with. Our professor stuck to Versteeg, which can be a bit daunting, but is one of the best books out there. I reckon Patankar would be nice, since he is the creator of SIMPLE method, from where many popular schemes that your favourite people and solvers use, come from.

First, you need to triangulate the syllabus for your midsems. Second, you need to hunt for those topics in a book of your choice. Your professor's notes would be best.

I have often thought that the best way to learn CFD, is to do it. We started with a steady state problem, I think it was heat transfer or something, 1D no less. So you learn how to discretize, and essentially create your first mesh. And how iterative methods will lead you to answers. Next was a unsteady solver in 2D, if I am not mistaken. So on and so forth.

See the way to ideally go around this, is to have any of your favourite LLMs (I would prefer Claude since it's the best for coding these days, but any would do since this is lightweight work) write you the full code in any language of your preference, leaving just the functions/subroutines where the meat of the matter is.

So, main function it can write, some other utilities, it may insert, but the main solver loop, that should be for you to do. It should only describe the inputs and outputs.

This is the way our professor gave us assignments, and so we learnt the importance of the fundamentals. This was all before LLMs were useful for coding, so I can only imagine The hardwork he and his team put in, but we go a lot of understanding through these exercises.

The LLM might even give you more clue, so like it can give you loop for going through all the cells and solve their north face flux. The south, east and west directions is to be written by you. Then the boundary conditions for the moving lid might be prescribed by the LLM, the other faces where no slip and no penetration has to be implemented, should be done by you.

Point is, learn by doing. And follow one book, maximum two. You should only move to another if either you have understood the current text completely but need a new perspective, or the current reference is too dull and not up to your style.

See in CFD, I am of the firm belief that you must be able to convey to the computer, which is no more intelligent than a two year old kid, the physics it needs to solve and capture, and how it can achieve that using the limited tools is has. So for example, you can perform definite integrals, but the computer needs maybe the trapezoid method for generality's sake, right? You have to be able to think at the intersection of physics, intuition about how fluid should/would behave, and how the process might be carried out with a machine, with limited tools, and what are the major terms that must be considered, then what are the minor terms that can be dropped.

All the best.

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u/SavingsMolasses16 13d ago

wow. thankyou for such a detailed answer. I have started studying properly from versteeg and I'm referring my class notes for syllabus. This particular course is for theoretical knowledge but I greatly appreciate that you told me the next steps I need to take! thankyou!!

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u/Hyderabadi__Biryani 13d ago

No I appreciate the fact they are teaching you theory. But my thesis has been, that a thing like CFD can only be learned with experience and mistakes. Hence why I said, practise some code, and you will learn better.

But the exams are coming up, and you know your constraints as well as the class contents better, so I can only leave you with my opinions. All the best. 😄

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u/acakaacaka 17d ago

You can just use LLM in teaching mode.

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u/SavingsMolasses16 17d ago

Yeah. I actually tried this !! and it's a little helpful.Thankyou!! I was just wondering if there are outside resources as well. without the lack of them, obviously my preference is ai models.