CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Question regarding non-uniform FVM staggered grid and order accuracy (http://www.cfd-online.com/Forums/main/108523-question-regarding-non-uniform-fvm-staggered-grid-order-accuracy.html)

 quarkz October 25, 2012 09:56

Question regarding non-uniform FVM staggered grid and order accuracy

Hi,

I have a question regarding non-uniform FVM staggered Cartesian grid and order accuracy.

When the grid is non-uniform, I define the u,v,p grids such that the east/west faces of the u grid intersects the cell center of p. Same for the v grid.

In that case, the distance of the east/west faces from the cell center of u will be different. the volume of u and p cells are different.

When using the fractional method, after evaluating the pressure from the Poisson eqn, to get u velocity, I use:

u(n+1) - u(*) = -(delta_t / vol) * pressure(east face) -pressure(west face) * area, where u*) is the intermediate velocity

However, since my u value is not at the center of the cell, it will not give a 2nd order solution, is that so? How can I resolve this?

Thanks

 FMDenaro October 25, 2012 11:22

Quote:
 Originally Posted by quarkz (Post 388489) Hi, I have a question regarding non-uniform FVM staggered Cartesian grid and order accuracy. When the grid is non-uniform, I define the u,v,p grids such that the east/west faces of the u grid intersects the cell center of p. Same for the v grid. In that case, the distance of the east/west faces from the cell center of u will be different. the volume of u and p cells are different. When using the fractional method, after evaluating the pressure from the Poisson eqn, to get u velocity, I use: u(n+1) - u(*) = -(delta_t / vol) * pressure(east face) -pressure(west face) * area, where u*) is the intermediate velocity However, since my u value is not at the center of the cell, it will not give a 2nd order solution, is that so? How can I resolve this? Thanks

I suggest to see the dedicated part in:

http://onlinelibrary.wiley.com/doi/1...d.613/abstract
http://onlinelibrary.wiley.com/doi/1...al+maintenance