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-   -   Multigrid with Neumann Boundary Conditions (http://www.cfd-online.com/Forums/main/9891-multigrid-neumann-boundary-conditions.html)

Davoche September 16, 2005 12:05

Multigrid with Neumann Boundary Conditions
 
Hi everybody, I've just implement a 3D MultiGrid code with Dirichlet boundary condition which works well.

I'm now trying to resolve a Poisson equation with free boundary conditions. But,I have never dealed with Neumann Conditions (dP/dx=0) at the boundary ( wall ). I have a cell centered resolution and a finite difference scheme.

In fact, I'm wondering if it is sufficient to impose, in the relaxation process, the following p(i+1)=p(i) (where p(i)is a value at the boundary) to impose a Neumann B.C. ??

Thanks

Davoche

Davoche September 17, 2005 11:25

Re: Multigrid with Neumann Boundary Conditions
 
I formulate it in a different manner: How to impose Neumann boundary condition in a simple iterative (relaxation) method ?

Tanaka September 20, 2005 07:16

Re: Multigrid with Neumann Boundary Conditions
 
Hi All! I want to implement multigrid technique in my THREE Dimensional NS code with cartesian grid. Would anyone please tell in simple terms how to transfer the variables from one grid level (finer) to next grid level (coarser) and vice-versa. I want to grasp the concept. Thank you in advance. Tanaka..


Davoche September 22, 2005 04:46

Re: Multigrid with Neumann Boundary Conditions
 
You can take a look in Numerical Recipes for that. It is in 2D cartesian, but the concept is clearly explain and you can easily transpose it to a 3D case. Hope it will help...



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