Dear friends:

I am studying Ferziger J.H., Peric M.'book, <computatinal method for fluid dyanmic>, i have many confusion about the code.

so i want to know any friends are fimiliar with it. i want to have some discussion with you.

my skype:technical money regards

Drop your doubts. If I know I can help you

Dear frieds: i have sent a emai to you

please send it again

hi, i also work on cfd and have been using the code provided within the book. If you still need to discuss, just drop me a message. Regards

[miad]

Originally Posted by epb
;56451

hi, i also work on cfd and have been using the code provided within the book. If you still need to discuss, just drop me a message. Regards

I am trying to use ferziger and peric book code for turbulent flow(k-epsilon model)
to analyze viscous flow around an aerofoil.I am having some troubles.Can you please help me in this regard?

[FMDenaro]

If you are involved in RANS modelling I suggest reading a more specific textbook, for example Wilcox

[miad]

I am using the code for turbulent flow (k-epsilon model) of Ferziger and Peric book.I want to know the steps used by the code to solve transport equations.Does it solve the momentum equation and equation for k and epsilon separately or they are solved simultaneously.

[arjun]

Originally Posted by miad

I am using the code for turbulent flow (k-epsilon model) of Ferziger and Peric book.I want to know the steps used by the code to solve transport equations.Does it solve the momentum equation and equation for k and epsilon separately or they are solved simultaneously.

Do you mean you already have the code by Mr. Peric and you want to understand how it was done?

Or do you want the code that he wrote?

[miad]

I actually have the code.But i have a vague understanding of how it works.Is there any way I can get to see the detailed steps followed for a single iteration?I understand that we solve k-epsilon equation and get values of eddy viscosity to get reynolds stresses to close the momentum equations.And wall functions are used near the wall(inner layer).But i want to manually perform one iteration to understand the exact step by step numerical procedure.Sorry if i am asking for too much.But unfortunately that is what my thesis supervisor wants from me.

[arjun]

These turbulence equations are transport equations and Mil0van\s book mention them how they need to be discretized.

But for more clear explanation is given in book by

https://books.google.co.in/books/abo...ir_esc=y&hl=en

There is nothing special in these equations, there are only three issues to understand

1. How the source terms are computed from velocity gradients and viscosity.
2. How the wall stresses are computed using wall laws.
3. How the turbulence viscosity is computed using gradients etc.

I haven\t seen Milovan\s code for long time I don't remember it in details.



If you want to code or understand the Malalasekara's book is more useful and easy to understand. I wpuld look into it first and then in Milovan's book.

[miad]

Thank you for the reply.I am following the book already(I am not sure about the edition though)I am aware of the summary of the method but when I try to calculate one iteration manually without code,I fail.So I was looking for a test case,where i can actually follow each and every step.Can you suggest me any book than can help me in this regard?

[arjun]

Originally Posted by miad

Thank you for the reply.I am following the book already(I am not sure about the edition though)I am aware of the summary of the method but when I try to calculate one iteration manually without code,I fail.So I was looking for a test case,where i can actually follow each and every step.Can you suggest me any book than can help me in this regard?

I think what you are trying to do is really tough. It looks easy on paper when you try to write down it as steps as first calculate gradients then assemble equations and on and on. But when you really want to do on paper, even the smallest grid that you might have would be say 3x3 to be really meaningful. Now that is 27 cells and then you are will need to compute 6 x 3 gradient variables. Then assembling various equations like momentum continuity etc is challenging task on paper.

So don't do.

As far as turbulence equations go, Versteegs book has worked example for convection diffusion term that you can also do. Milovan's book also has worked example for it (3rd or 4rth chapter).

All one need to do then is to add the source terms.

I pointed to another book so that you can follow the example and do calculations on paper or in small code. Versteeg i believe write various values you get when you do the calculations so that you can check. Milovan's book writes how they are assembled but does not write numerical values for example problem and only the results.

PS: This is based on what i can recollect.

[miad]

Thanks for your reply.I really appreciate the time you took to write for me

[arjun]

Originally Posted by miad

Thanks for your reply.I really appreciate the time you took to write for me

If you want to understand how cfd solver works better idea would be to download inavier that i wrote long time ago. Older versions are available on sourceforce.

Download eclipse ide and browse the code. You will understand how you can write unstructured grid based solver. I believe inavier does not have k epsilon but it has k omega, spalart Almaras and some LES subgrid models.

PS: Latest version of iNavier is also there that had lots of interesting things, but i have looked at it for last 2 or 3 years and not available online.
I started writing FVUS/Wildkatze and busy with it.

[miad]

Thank you.I am going to download iNavier..Currently my supervisor wants me to generate results for viscous flow around a hydrofoil using the Ferziger and peric book code at various angles of attack.I hope I can yield some good results that will please him..Do you have access to the paper by Demirdzic, C Muzaferija and Peric (1996)?The code suggests to read this paper

[arjun]

Originally Posted by miad

Thank you.I am going to download iNavier..Currently my supervisor wants me to generate results for viscous flow around a hydrofoil using the Ferziger and peric book at various angles of attack.I hope I can yield some good results that will please him.

Is it incompressible flow or compressible flow.

BTW I started iNavier as project for me to learn all this and also to write something as add on to Milovan's codes. The reason was his codes don't have anything for unstructured grid so I tried to make one such code. The idea was students can look into it and learn.

Anyway Milovan's codes are in fortran and iNavier is in C++.

Also note that it is better to do what supervisor says, use iNavier for just learning what is done.

[miad]

I am working on incompressible flow.I have generated results for zero angle of attack(lucky).But I am having trouble generating correct values of Cp(pressure coefficient) for non zero angle of attack.Also I am having some troubles understanding the input file for the solver.