how can i start writing CFD code?

alirezavatandoust · September 30, 2009, 16:25

hi ,
i'm trying to start writeing a CFD code by C++, but I dont know what the steps are.

is anybody there to help me please?cheers

nsalpeter · September 30, 2009, 17:25

If you are really wanting to write something on your own (*shudders at painful memories*) your first step might be sitting down with "Numerical Heat Treansfer and Fluid Flow" by Suhas Patankar.

This book is largely regarded as the bible of CFD. It won't get into the most nitty gritty of turbulence models, but it will give you some pretty clear numerical methods and strategies for going about writing your own code.

dominic · September 30, 2009, 19:44

Some of the important points are
* Know what you want to do and what you are doing. You must be clear on what you want to formulate and solve.

*Write down a small algorithm, or something like a structure of the code.. like what are the inputs required.. what is your time stepping.... what is your discretization scheme used... etc. Think of what parameter you are interested to monitor and print out finally.

*Initially don't bother about syntax errors. Just write in the code as if you are writing in plain English. At places where you feel that, the block of code would be large, just replace it by a function call.... say solve(). Do not worry about declaring variables now..

*After you are having an idea of your code structure, now you can correct your code, by declaring the variables, defining the functions etc..

Also take a look at many CFD codes (small) available in the web or in books for you to get a feel.

Happy coding !
Dominic

praveen · September 30, 2009, 22:45

In addition to the previous advice:

Start with a 1-D code. Solve some problems like quasi-1D nozzle, etc

Then go to 2-D. Flate plate, lid-driven cavity, maybe an airfoil, etc.

By this time, you would have a pretty good idea.

Then 3-D.

You seem to be totally new to this. Start with very simple things. Anderson's CFD book is quite good for beginners. Initially write a lot of code on your own. Then start looking at other people's codes. Many of them are freely available on the internet.

alirezavatandoust · October 2, 2009, 07:41

hi everyone !
thanks for your help
those were realy helpful.
cheers

alirezavatandoust · October 2, 2009, 07:43

hi!
should I use any modeller and mesher software?which one is more suitable?
thanks

September 30, 2009, 16:25	how can i start writing CFD code?	#1
alirezavatandoust New Member ali Join Date: Sep 2009 Posts: 3 Rep Power: 16	hi , i'm trying to start writeing a CFD code by C++, but I dont know what the steps are. is anybody there to help me please?cheers

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September 30, 2009, 17:25		#2
nsalpeter New Member Nate Salpeter Join Date: Apr 2009 Posts: 4 Rep Power: 16	If you are really wanting to write something on your own (shudders at painful memories) your first step might be sitting down with "Numerical Heat Treansfer and Fluid Flow" by Suhas Patankar. This book is largely regarded as the bible of CFD. It won't get into the most nitty gritty of turbulence models, but it will give you some pretty clear numerical methods and strategies for going about writing your own code.

September 30, 2009, 19:44		#3
dominic Member Dominic Chandar Join Date: Mar 2009 Location: United Kingdom Posts: 31 Rep Power: 17	Some of the important points are * Know what you want to do and what you are doing. You must be clear on what you want to formulate and solve. Write down a small algorithm, or something like a structure of the code.. like what are the inputs required.. what is your time stepping.... what is your discretization scheme used... etc. Think of what parameter you are interested to monitor and print out finally. Initially don't bother about syntax errors. Just write in the code as if you are writing in plain English. At places where you feel that, the block of code would be large, just replace it by a function call.... say solve(). Do not worry about declaring variables now.. *After you are having an idea of your code structure, now you can correct your code, by declaring the variables, defining the functions etc.. Also take a look at many CFD codes (small) available in the web or in books for you to get a feel. Happy coding ! Dominic

September 30, 2009, 22:45		#4
praveen Super Moderator Praveen. C Join Date: Mar 2009 Location: Bangalore Posts: 342 Blog Entries: 6 Rep Power: 18	In addition to the previous advice: Start with a 1-D code. Solve some problems like quasi-1D nozzle, etc Then go to 2-D. Flate plate, lid-driven cavity, maybe an airfoil, etc. By this time, you would have a pretty good idea. Then 3-D. You seem to be totally new to this. Start with very simple things. Anderson's CFD book is quite good for beginners. Initially write a lot of code on your own. Then start looking at other people's codes. Many of them are freely available on the internet.

October 2, 2009, 07:41		#5
alirezavatandoust New Member ali Join Date: Sep 2009 Posts: 3 Rep Power: 16	hi everyone ! thanks for your help those were realy helpful. cheers

October 2, 2009, 07:43		#6
alirezavatandoust New Member ali Join Date: Sep 2009 Posts: 3 Rep Power: 16	hi! should I use any modeller and mesher software?which one is more suitable? thanks