Slip-Condition

CFDJonas · September 22, 2021, 07:44

Hello!

I'm currently trying to implement a Fluent case with a specified slip velocity. However, the boundary condition only allows me to use the no-slip condition or to specify a shear stress with the corresponding vector components.

I then thought, I could calculate the vector components to result in a constant slip velocity, but this doesn't seem to work with my current understanding of the stress tensor.

When I look into the Ansys manual (https://www.afs.enea.it/project/nept.../th/node11.htm), the stress tensor is a result of the viscosity and some kind of velocity derivatives. But exactly the latter one need to be zero (in my understanding) to result in a constant slip velocity... What should I therefore enter in the shear stress components? Or is this a completely bad route I'm trying to take?

I am grateful for any information you could provide me, to better understand this topic. Thank you!

For anyone wondering, I need to implement an "apparent" slip-condition, as already reported for polymer solutions in literature.

LuckyTran · September 22, 2021, 15:21

If you're trying to impose the velocity at a boundary, use a velocity inlet. Or you can even use a no slip moving wall.

javidhedayat · February 21, 2024, 18:21

Hey Jonas,

I was wondering if you could sort it out?

Quayson-Sackey · February 26, 2024, 11:43

Hello Jonas,
I am also facing the same problem . Can you please share with us if you found solution to that.

September 22, 2021, 07:44	Slip-Condition	#1
CFDJonas New Member Join Date: May 2018 Posts: 29 Rep Power: 8	Hello! I'm currently trying to implement a Fluent case with a specified slip velocity. However, the boundary condition only allows me to use the no-slip condition or to specify a shear stress with the corresponding vector components. I then thought, I could calculate the vector components to result in a constant slip velocity, but this doesn't seem to work with my current understanding of the stress tensor. When I look into the Ansys manual (https://www.afs.enea.it/project/nept.../th/node11.htm), the stress tensor is a result of the viscosity and some kind of velocity derivatives. But exactly the latter one need to be zero (in my understanding) to result in a constant slip velocity... What should I therefore enter in the shear stress components? Or is this a completely bad route I'm trying to take? I am grateful for any information you could provide me, to better understand this topic. Thank you! For anyone wondering, I need to implement an "apparent" slip-condition, as already reported for polymer solutions in literature.

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September 22, 2021, 15:21		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	If you're trying to impose the velocity at a boundary, use a velocity inlet. Or you can even use a no slip moving wall.

February 21, 2024, 18:21		#3
javidhedayat New Member Javid Join Date: May 2023 Posts: 1 Rep Power: 0	Hey Jonas, I was wondering if you could sort it out?

February 26, 2024, 11:43		#4
Quayson-Sackey New Member Emmanuel Quayson-Sackey Join Date: Feb 2024 Posts: 2 Rep Power: 0	Hello Jonas, I am also facing the same problem . Can you please share with us if you found solution to that.