
[Sponsors] 
May 11, 2010, 12:04 
Boundary condition of cellcentered FVM

#1 
New Member
Edward
Join Date: Jul 2009
Posts: 12
Rep Power: 0 
Is it possible to make the velocity be zero exactly at solid boundary(viscous no slip BC) by the cellcenterd finite volume method, i knew finite difference method and vertex based finite volume method can do that ,but not clear of whether cell centered FVM could or not


May 11, 2010, 16:10 

#2  
New Member
Jiannan
Join Date: Mar 2009
Posts: 10
Rep Power: 9 
Quote:
Good luck! 

May 11, 2010, 18:26 

#3 
New Member
Rich
Join Date: Aug 2009
Location: Montrose, Colorado, USA
Posts: 11
Rep Power: 9 
Jackson:
I agree with Jiannan, it does work. I've also used it. For a viscous flow, you can simply set the velocity in the nexttoboundary cells to zero. For an inviscid flow, where the velocity in those cells is finite and always parallel to the surface, you have to be more formal. I've found that you can derive governing equations that apply specifically to the boundary cells. In an inviscid flow, the "V dot dS" term in the integral form of the governing equations is always zero for the cell wall that forms the boundary. Rederive your equations with that term set to zero for that wall and apply them to the boundary cells, and those cells operate just as they should. Rich 

May 11, 2010, 21:02 

#4  
New Member
Edward
Join Date: Jul 2009
Posts: 12
Rep Power: 0 
Set the velocity in the nexttoboundary cells to zero is not strictly right way? Is there a more accurate method? For my code, i give some special treatments for no slip B.C:
1.gradient computation in the cell next to wall boundary(Gauss Green Method,the face velocity on wall is set zero ) 2.i think the flux on wall is the same as inviscid flux,so no more special treatment 3.viscous flux calculation contains face velocity and it is set zero exactly Then the code ran, but i found the velocity on boundary face is not zero by Tecplot..................... IS THERE SOME PROBLEMS OF MY TREATMENT? THANK YOU FOR YOUR HELP Quote:


May 12, 2010, 00:09 

#5  
Super Moderator

Quote:
For cellcentered scheme, boundary conditions are imposed through appropriate definition of boundary fluxes. Dont worry if tecplot shows velocity on boundary not satisfying the boundary condition. Tecplot does not know your boundary condition, so it is doing some interpolation to get the boundary values. 

May 13, 2010, 15:55 

#6  
New Member
Rich
Join Date: Aug 2009
Location: Montrose, Colorado, USA
Posts: 11
Rep Power: 9 
Quote:
Rich 

May 13, 2010, 16:19 

#7  
Senior Member
Arjun
Join Date: Mar 2009
Location: Nurenberg, Germany
Posts: 484
Rep Power: 13 
Quote:
that probably is interpolation issue. 

May 14, 2010, 08:23 

#8  
New Member
Edward
Join Date: Jul 2009
Posts: 12
Rep Power: 0 
i output the cellcentered value for tecplot cell centered mode,tecplot auto interpolate them to vertexes, i changed it to cell centered display mode and found it is not closed to zero. so i think it is not interpolation's problem. can someone offer me some paper about
the implement of BC? Quote:


Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
SymmetryPlane Boundary Condition  raytracer  OpenFOAM Running, Solving & CFD  0  July 11, 2008 17:04 
Airfoil boundary condition  Frank  Main CFD Forum  1  April 21, 2008 18:36 
Boundary Condition When using FVM?  leaf  Main CFD Forum  2  December 5, 2007 04:53 
Rotating interpolated boundary condition  hani  OpenFOAM Running, Solving & CFD  0  July 4, 2006 07:09 
How to visualise cell centered FVM mesh?  assabari  Main CFD Forum  1  March 1, 2001 08:39 