CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   Reynolds Stress Model and Free Surface Flows (

Zaktatir April 13, 2012 06:09

Reynolds Stress Model and Free Surface Flows
Hello dear community,

Have anyone an idea how to damp the normal fluctuations in case of air/water stratified flows. Two-Equations modeling assume isotrop, which ma be fatal, while dealing with very turbulent stratification. The Ansatz of turbulence damping with Two-Equations Models leads to the damping of the turbulence production which is wrong, since only normal fluctuations vanish near the free surface.

Jessica :)

kbaker April 14, 2012 14:46

Hello I am not sure If I understood what you mean with damping normal fluctuations? May you explain more about your problem and what you trying to predict? Is the normal fluctuations type of waves at the interface? If it wavy flow the k-e model unsuitable due to the anisotropy of properties, hence the Reynold Stress Model is more applicable for this case which can predict the secondary flows over the interface. I have a lot of papers about the stratified wavy flow and secondary flow in stratified flow too but I not model it within CFX code yet and I am currently starting with it.


Zaktatir April 17, 2012 09:42

that is the same thing, which i am trying to do.

mariam.sara April 17, 2012 10:34

Hi there is some things I need to ask you about your case of study hope it help me with my simulations:
1)is it a pipe flow case? if so is it 2D or 3D problem?
2)did you consider the phases flows with the same velocity at inlet or flows with different velocities? if different how you set it at inlet for both phases?

Zaktatir April 17, 2012 11:38

Channel Flow with 2D Assumption for developing the model. Then is would be test on an full 3D-geometry.

I am using the inhomogeneous model (euler/euler approach). Every fluid possesses his own velocity field overall in the domain.

kbaker April 17, 2012 12:05

hi Did you define the velocity of each phase using CEL expression or you divide the inlet into two parts (one for the first fluid and the second to the other)?

All times are GMT -4. The time now is 11:01.