Help regarding pressure gradient
Hi Guys,
I had formulated the problem combining Navier Stokes with Energy Equation. For that I wanted to try out Couette flow with pressure gradient (*plane Poiseuille flow*) with Thermal boundary conditions. For simple Couette Flow ( pressure gradient =0 ) the code is working fine and giving us the proper velocity profile but how to do it with user defined pressure gradient. See Link - http://www2.mech.kth.se/~luca/Smak/rec5.pdf which will give us velocity profile for this flow. I tried imposing pressure boundary condition but it is not working out. I have attached the problem file.
Regards, Ankit
Hi Ankit,
(IMHO as always when talking about NS) the pressure in incompressible NS equations is just a Lagrange multiplier for enforcing the incompressibility constraint and it is determined up to a constant. So Dirichlet bcs are not the way to go. To impose pressure as "volumetric stress traction" you will need Neumann-type bcs (dw_surface_ltr), but be careful in deriving the weak form of the NS equations - do not forget some terms from integration by parts.
r.
On 07/24/2013 10:46 AM, Ankit Mahato wrote:
Hi Guys,
I had formulated the problem combining Navier Stokes with Energy Equation. For that I wanted to try out Couette flow with pressure gradient (*plane Poiseuille flow*) with Thermal boundary conditions. For simple Couette Flow ( pressure gradient =0 ) the code is working fine and giving us the proper velocity profile but how to do it with user defined pressure gradient. See Link - http://www2.mech.kth.se/~luca/Smak/rec5.pdf which will give us velocity profile for this flow. I tried imposing pressure boundary condition but it is not working out. I have attached the problem file.
Regards, Ankit
On Wednesday, 24 July 2013 15:52:19 UTC+5:30, Robert Cimrman wrote:
Hi Ankit,
(IMHO as always when talking about NS) the pressure in incompressible NS equations is just a Lagrange multiplier for enforcing the incompressibility constraint and it is determined up to a constant. So Dirichlet bcs are not the way to go. To impose pressure as "volumetric stress traction" you will need Neumann-type bcs (dw_surface_ltr), but be careful in deriving the weak form of the NS equations - do not forget some terms from integration by parts.
okie R.
r.
Hi Guys,
I had formulated the problem combining Navier Stokes with Energy Equation. For that I wanted to try out Couette flow with pressure gradient (*plane Poiseuille flow*) with Thermal boundary conditions. For simple Couette Flow ( pressure gradient =0 ) the code is working fine and giving us the
On 07/24/2013 10:46 AM, Ankit Mahato wrote: proper
velocity profile but how to do it with user defined pressure gradient. See Link - http://www2.mech.kth.se/~luca/Smak/rec5.pdf which will give us velocity profile for this flow. I tried imposing pressure boundary condition but it is not working out. I have attached the problem file.
Regards, Ankit
participants (2)
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Ankit Mahato -
Robert Cimrman