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-   -   the step size used in Gridgen (http://www.cfd-online.com/Forums/pointwise/5230-step-size-used-gridgen.html)

 yang October 1, 2002 15:49

the step size used in Gridgen

Hi there, I've got a confusing problem with the spacing size when using Gridgen.

As we all know, based on the grid generated by Gridgen, we could discretise N-S equations on a rectangular domain(computational domain). The question is how to determine the step size since Gridgen doesn't provide any information on this.

I've read many articles, it seems like the choice of stepsize in the computational domain is arbitrary. For convenience, many people choose 1.0 as the stepsize. Is it true?

Thanks a lot.

 versi October 1, 2002 23:19

Re: the step size used in Gridgen

The grid size in computational domain will not affect the solution, rather, it is the metric coefficient that will determine the solution.

 yang October 2, 2002 10:32

Re: the step size used in Gridgen

Thanks versi. Since the grid size plays no role in computation, what about the Courant number,which involves step size,i.e. dx?

 papiya roy October 3, 2002 04:50

Re: the step size used in Gridgen

hi i really want to know about the grid generation please let me inform. thankig you papiya roy

 versi October 4, 2002 05:09

Re: the step size used in Gridgen

In curvilinear coordinates

dt = CFL/ ( |U_contra| + |V_contra| + a sqrt ( (\xi_x)^2+ (\xi_y)^2 +(\eta_x)^2+(\eta_y)^2) ), so again you see that only metric coefficents are concerned. Dx is already taken into account in metric coefficient.

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