hi every body,

i need to make a simulation for two high speed trains running in opposite directions.

i tried that on FLOTRAN but with no result.

i need to know what program can do that and how can i get it.

also, what is the difference between the turbulence models, (i.e. the physical meaning of each one) and which model is suitable for my peoblem.

I think CFX did the trains years ago. Ask their sales rep. To locate them, use Google to find their web page.

I can't help you with the turbulence question.

Any modern commercial code should be able to do the problem you mentioned (fluent, cfx, etc)

Your turbulence model questions are very ambiguous - there are several books which attempt at answering your questions. Turbulence is a science in itself and a lot of people have devoted their entire reseach careers to it. You'd better pull out a couple of books or find some papers which can answer some of your question.

The part where you ask, "...and which model is suitable for my problem", to partially answer that is that turbulence models are problem dependent, meaning that there is no universal turbulence model. All you can do is use the existing ones with their assumptions which may or may not be valid for your problem.

Investigating the effects of turbulence models is part of the CFD process these days ... at least until computers become sufficiently powerful enough to perform DNS on more complex problems ... which won't be for quite some time.

StarCD can do it and infact has a tutorial for exactly your type of problem. check it out. Also I am pretty sure that Fluent can also do this using sliding mesh.

many thanks

Respected sir/madam

I studied K-E models Reynold equation model, and reynolds stress models. But how can i solve those problems with a small aplication involving a turbulence. I want to confirm that it can be solved by finite difference or any other.. and if any other means can u please explain about that..

Thanking you,

yours faithfully R.Manimaran

Hi there,

If you don't want to try/buy a commercial CFD-program, I believe that a number of simpler CFD-codes may be available on the internet. It is not easy to program a CFD-code without proper guidance and help, however you will probably find all that you need on internet.

Cheers Jonas

Dear Jonas,

Please let me know the free 3D CFD code I can get through the internet.

Regards,