[petsc-users] Modify RHS values at each iteration

[Jed Brown]

TAY wee-beng <zonexo at gmail.com> writes:

> Hi Jed,
>
> I need a solve a Poisson equation, which is part of my finite volume CFD 
> code.
>
> The RHS terms are calculated from the velocity.
>
> In the standard mtd, the RHS terms are calculated from the velocity, 
> which then solves the Poisson eqn to get the pressure.
>
> Now, to improve the accuracy of the pressure obtained, a paper suggested 
> obtaining the pressure  from the velocity in 1 iteration. Then use the 
> new pressure for the momentum eqn to get a more accurate intermediate 
> velocity. The RHS terms are recomputed again using the new velocity, 
> which is then used to calculate the new pressure. This cycle goes on 
> until the pressure converges to a certain value.

This is a crude iterative method for solving a coupled problem.  I
recommend that you solve the coupled problem.  See the section of the
user's manual on solving block problems, and the examples in PETSc that
solve Stokes-type problems.
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