# Slip & No Slip Conditions

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 February 2, 2011, 07:15 Slip & No Slip Conditions #1 Member   Kurne Join Date: Aug 2010 Location: Pune, INDIA Posts: 88 Rep Power: 8 Dear All Will anybody please tell me how to give the Slip and Noslip conditions at the wall.I am bit confused, whether slip means zeroGradient and Noslip means fixedGradient. lijinghua_lee, vahid.najafi and roshan1 like this. __________________ Simulation Is Determination Of Imagination Towards Approximation ® Best Regards Mubeen K Kurne

 February 2, 2011, 07:25 #2 Senior Member   Anonymous Join Date: Mar 2009 Posts: 110 Rep Power: 9 To implement no-slip, use: type fixedValue; value (0,0,0); To implement slip, use: type slip; solefire, Mojtaba.a, vahid.najafi and 7 others like this.

 February 2, 2011, 07:39 #3 Member   Kurne Join Date: Aug 2010 Location: Pune, INDIA Posts: 88 Rep Power: 8 Dear madad2005 Thanks A lot for help.Will you please correct me For No Slip conditions 1) For velocity type fixedValue; value uniform 0; 2) For pressure type fixedValue; value uniform 0; For Slip Conditions 1) For velocity type slip; 2) For pressure type slip; Thanks In Advance __________________ Simulation Is Determination Of Imagination Towards Approximation ® Best Regards Mubeen K Kurne

February 2, 2011, 07:57
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Anonymous
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Quote:
 Originally Posted by kurne Dear madad2005 Thanks A lot for help.Will you please correct me For No Slip conditions 1) For velocity type fixedValue; value uniform (0,0,0); 2) For pressure type zeroGradient; For Slip Conditions 1) For velocity type slip; 2) For pressure type zeroGradient; Thanks In Advance
See above. The BC requirement for pressure at the wall is normally zeroGradient. For velocity with a slip wall, there are two different conditions to be met normal to the wall and parallel to the wall, which I believe the slip boundary condition handles.

 February 2, 2011, 08:05 #5 Member   Kurne Join Date: Aug 2010 Location: Pune, INDIA Posts: 88 Rep Power: 8 Dear mada2005 Thank you very much for guiding me. Thanks Once Again. __________________ Simulation Is Determination Of Imagination Towards Approximation ® Best Regards Mubeen K Kurne

November 20, 2013, 13:58
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Prashant Gupta
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Quote:
 Originally Posted by madad2005 See above. The BC requirement for pressure at the wall is normally zeroGradient. For velocity with a slip wall, there are two different conditions to be met normal to the wall and parallel to the wall, which I believe the slip boundary condition handles.
Hi all,
sorry to revive such an old post.
1. If I use full-slip for velocity, is there a need to specify pressure ? I guess it should calculate using the velocity at the wall ?

2. What if I use pressure bc as "slip" as well with Velocity bc as "slip" . It should be same as pressure bc "zeroGradient" ? I do not get same answers if I do this.

 August 19, 2016, 15:35 #7 New Member   Sydney Join Date: Jun 2016 Posts: 4 Rep Power: 2 1. Yes, I think you generally need to specify zeroGradient, but you're right sometimes depending on the solver the 'boundary condition' for pressure is pre-determined by the velocity boundary conditions. 2. I think slip might be sort of a vector boundary condition (different equations for different vector components), and since pressure is a scalar maybe it took the first condition of slip (which could be the no penetration equation u1=0) as the pressure boundary condition instead of d u2 / dn = 0.

 August 24, 2016, 06:54 #8 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,519 Blog Entries: 6 Rep Power: 27 An old topic, isn 't it Sgs? noSlip is a vector class and hence it can not be used for the pressure. noSlip is similar to fixedValue uniform (0 0 0); The slip boundary condition is a template class and therefore we can use any kind of fields. If we have a scalar it will set it to zeroGradient (I did not check this out, so it is just a logical consequence). For a vector field, the normal component should be zero (sliding). It would be a wall (no fluxes can pass) but there is finally no shearing based on the fact that we assume that there are no viscous effect. __________________ Best regards, Tobias Holzmann Some interesting OpenFOAM tutorials, publications and videos on www.Holzmann-cfd.de OpenFOAM Beginners should check out the new wiki on wiki.openfoam.com A list of some active OpenFOAM contributers can be found »here« A book about the basics of »Mathematics, Numerics, Derivations and OpenFOAM« can be found on www.Holzmann-cfd.de

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