Reynolds Stress Model and Free Surface Flows

Zaktatir · April 13, 2012, 06:09

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.

REGARDS
KBaker

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)?

April 13, 2012, 06:09	Reynolds Stress Model and Free Surface Flows	#1
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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

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April 14, 2012, 14:46		#2
kbaker Senior Member Khalid Baker Join Date: Mar 2009 Location: IRAQ Posts: 168 Rep Power: 17	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. REGARDS KBaker

April 17, 2012, 09:42		#3
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	that is the same thing, which i am trying to do.

April 17, 2012, 10:34		#4
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	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?

April 17, 2012, 11:38		#5
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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.

April 17, 2012, 12:05		#6
kbaker Senior Member Khalid Baker Join Date: Mar 2009 Location: IRAQ Posts: 168 Rep Power: 17	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)?