# Boundary condition for compressible flow ( cavity lid problem)

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 May 3, 2012, 00:50 Boundary condition for compressible flow ( cavity lid problem) #1 New Member   pawan goyal Join Date: May 2012 Posts: 1 Rep Power: 0 Hey all I have been working on CFD modelling for compressible flow. I have flour parameters at each node ( density,velocity in x& y direction,temperature). I have taken advantage of ideal gas low. I have assumed isothermal wall. So i have boundary condition for velocities, temperature but I could not derived the boundary condition for density. Could anyone please let me know the derivation for boundary condition for density. Thanks in advance and looking forward for reply. Regards Pawan Goyal

June 2, 2012, 16:58
#2
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Rahul Verma
Join Date: Jan 2012
Location: Mumbai
Posts: 7
Rep Power: 14
Quote:
 Originally Posted by pike@91 Hey all I have been working on CFD modelling for compressible flow. I have flour parameters at each node ( density,velocity in x& y direction,temperature). I have taken advantage of ideal gas low. I have assumed isothermal wall. So i have boundary condition for velocities, temperature but I could not derived the boundary condition for density. Could anyone please let me know the derivation for boundary condition for density. Thanks in advance and looking forward for reply. Regards Pawan Goyal
Hey pawan i am also working in compressible area. I have solved two dimensional shock tube problems with implicit scheme and i took full navier stokes equation as governing equation. you can use neumann boundary condition for boundary or you can extrapolate boundary density from nearest density value. Both thing will work.

I have one question for you. do you have any journal paper in which this lid cavity problem has been solved for compressible case.
I solved this lid driven cavity problem for incompressible case and it is perfectly working. But i am not sure about any benchmark or any paper for compressible cavity problem.

June 2, 2012, 17:04
#3
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,815
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Quote:
 Originally Posted by pike@91 Hey all I have been working on CFD modelling for compressible flow. I have flour parameters at each node ( density,velocity in x& y direction,temperature). I have taken advantage of ideal gas low. I have assumed isothermal wall. So i have boundary condition for velocities, temperature but I could not derived the boundary condition for density. Could anyone please let me know the derivation for boundary condition for density. Thanks in advance and looking forward for reply. Regards Pawan Goyal

you can try solving the continuity equation on the wall-node, of course considering the bc.s for the velocity field