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sreejith
science forum beginner
Joined: 29 Sep 2005
Posts: 9
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 Posted: Wed Jun 28, 2006 5:19 pm Post subject:
Pressure boundary condition when solving Stokes equation
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Could some one make clear the concepts (mathematical):
when solving stead Stokes in velocity-pressure formulation, how do we treat pressure (boundary condition). What does "pressure is known only upto a constant" and "imposing mean zero pressure" meant?
Thank You |
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Roy Stogner
science forum beginner
Joined: 13 Jun 2005
Posts: 38
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| Posted: Wed Jun 28, 2006 6:31 pm Post subject:
Re: Pressure boundary condition when solving Stokes equation
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On Wed, 28 Jun 2006 13:19:22 -0400, sreejith wrote:
| Quote: | Could some one make clear the concepts (mathematical):
when solving stead Stokes in velocity-pressure formulation, how do we
treat pressure (boundary condition).
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It depends on what you know about your boundary conditions. If you have a
specified velocity everywhere, for example, pressure doesn't appear in the
boundary conditions at all.
| Quote: | What does "pressure is known only up to a constant" and "imposing mean
zero pressure" meant?
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If you have a velocity/pressure field (V(x), p(x)) that solves a
particular incompressible Stokes flow problem with velocity boundary
conditions, then the field (V(x), p(x)+c) is also a solution for any
constant c.
Your solver may not like such an ill-defined problem (which generally
gives you a singular linear system), so people often impose some
additional condition on the pressure (such as the one you mentioned: make
the integral of pressure over the domain zero) to make the solution
unique.
---
Roy Stogner |
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sreejith
science forum beginner
Joined: 29 Sep 2005
Posts: 9
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| Posted: Wed Jul 05, 2006 2:28 pm Post subject:
Re: Pressure boundary condition when solving Stokes equation
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Thank you very much for your explanation. |
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