[anubasu]

Hi all,

I am simulating partially filled pipe flows using interFOAM. Which turbulence model is best to use? ke or komega?

Thanks

[saeed jamshidi]

Hello anubasu,

As far as I know, k epsilon turbulence medel is the best choice for confined flows such as flow inside a pipe or channel. Besides, use suitable y plus and wall functions for your problem.

Good luck.

[anubasu]

Originally Posted by saeed jamshidi

Hello anubasu,

As far as I know, k epsilon turbulence medel is the best choice for confined flows such as flow inside a pipe or channel. Besides, use suitable y plus and wall functions for your problem.

Good luck.

Hi saeed, ok thanks. I think it is best to compare the results using the 2 turbulence models.

[saeed jamshidi]

Allright, this would be more interesting approach.

Please, share your results for us to make comparison.

Tnx.

[anubasu]

Hi everyone,

I am a bit confused. For ke turbulence model y+ should be around 30, but do we need to give inflation layers? I am modeling fully turbulent partially-filled pipe flow using interFOAM. If without inflation layers I can get y+ around 30 is it not sufficient? I am a bit confused. ALso for komega, y+ should be around 1, so for that is inflation layer required?

Any help is greatly appreciated. Thanks.

[Tobermory]

Your question does not make any sense. You need to ensure that :

1. your mesh size is appropriate in all of the areas of the domain ... including at the wall;
2. the variation in cell size is suitably low, to minimise artificial diffusion effects.

How you achieve the above - with or without "inflation" layers - is entirely up to you.

[arjun]

Originally Posted by anubasu

Hi everyone,

I am a bit confused. For ke turbulence model y+ should be around 30, but do we need to give inflation layers? I am modeling fully turbulent partially-filled pipe flow using interFOAM. If without inflation layers I can get y+ around 30 is it not sufficient? I am a bit confused. ALso for komega, y+ should be around 1, so for that is inflation layer required?

Any help is greatly appreciated. Thanks.

This whole thing can be really confusing. In general there are three possibilities.



For turbulence models usually the values of epsilon or omega are set based on where the first cell near to wall is. (that is it is dependent on yplus and local turbulence Reynolds number).





Now there are three possibilities. The yplus is 5 or less or yplus is 30 or more and then third yplus is between 5 to 30.



First two cases (yplus < 5 and yplus > 30) we have clear formulas available and that can be used.



In the buffer that is between 5 to 30 there is a blending applied and the values are very sensitive to this blending.



The problem is that no one has perfect formula for it and this area is hit or miss.



So best is to avoid it. So use either yplus of 5 or less or 30 or more where we know what to be done.

[anubasu]

Thanks everyone, I will try to read further.