no-slip wall boundary condition

June 22, 2003, 06:04

I specified no-slip Wall boundary condition as one of the boundary conditions for my simulation. After solving, I export the velocity value along the line from wall to the free stream. I found that the velocity at the wall is not zero. In my case, it is 0.0321 m/s. Why isn't it zero? I think this might be the value at the center of the mesh next to the wall. Then how can CFX know, when it compute, that actually the velocity is zero at the wall? Thank you.

Atit

August 11, 2003, 22:57

When you are in post and you want to see velocity ther's 2 options Hybrid and Conservative (I think those are the names), you can choose these 2 options by toggle on one of them. In Hybrid you should see that the velocity is zero. I hope this will help you.

Marco

Stephen Waite · July 9, 2014, 17:24

Hello, I'm having the same problem, I set a constant temperature at a no-slip wall, however when I view the temperature and velocity in CFD-post at the wall they are not the values I specified.

I can see that the "conservative" boundary data tab is selected however I'm unable to change to hybrid because the boundary data tab is shadded (i.e. you can't select it). How can I change to hybrid?

Thanks

evcelica · July 10, 2014, 17:10

You can only display hybrid values of pre-defined variables in CFD-POST, not used defined variables.
Like if you made a variable Mytemp = Temperature, there wouldn't be hybrid values for Mytemp, even though there are for Temperature.

Other than that, I don't know why else it wouldn't work?

June 22, 2003, 06:04	no-slip wall boundary condition	#1
Atit Koonsrisuk Guest Posts: n/a	I specified no-slip Wall boundary condition as one of the boundary conditions for my simulation. After solving, I export the velocity value along the line from wall to the free stream. I found that the velocity at the wall is not zero. In my case, it is 0.0321 m/s. Why isn't it zero? I think this might be the value at the center of the mesh next to the wall. Then how can CFX know, when it compute, that actually the velocity is zero at the wall? Thank you. Atit

August 11, 2003, 22:57	Re: no-slip wall boundary condition	#2
Marco Melo Guest Posts: n/a	When you are in post and you want to see velocity ther's 2 options Hybrid and Conservative (I think those are the names), you can choose these 2 options by toggle on one of them. In Hybrid you should see that the velocity is zero. I hope this will help you. Marco

July 9, 2014, 17:24		#3
Stephen Waite New Member Stephen Waite Join Date: May 2013 Location: Auckland, New Zealand Posts: 29 Rep Power: 12	Hello, I'm having the same problem, I set a constant temperature at a no-slip wall, however when I view the temperature and velocity in CFD-post at the wall they are not the values I specified. I can see that the "conservative" boundary data tab is selected however I'm unable to change to hybrid because the boundary data tab is shadded (i.e. you can't select it). How can I change to hybrid? Thanks Last edited by Stephen Waite; July 9, 2014 at 18:29.

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July 10, 2014, 17:10		#4
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,140 Rep Power: 22	You can only display hybrid values of pre-defined variables in CFD-POST, not used defined variables. Like if you made a variable Mytemp = Temperature, there wouldn't be hybrid values for Mytemp, even though there are for Temperature. Other than that, I don't know why else it wouldn't work?