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| Grd_ni | : | total number of grid points in x-direction | |
| Grd_nj | : | total number of grid points in y-direction |
Global Yin-Yang grid
You need One only needs to specify the free/core number of points in y-direction (Grd_nj) as well as the "overlap" in degrees (Grd_overlap). The model will calculate the size of the grid boxes automatically from that.
| Grd_nj | : | core(!) /free number of grid points in y-direction Including overlap!!! => Number of points covering 90°+2*Grd_overlap | |
| Grd_overlap | : | overlap in degrees(!) |
Note that there is no blending/merging area, also called Davies sponge, in Yin-Yang grids, which means that the free area is the same as the core area!
To specify a Yin-Yang grid one should only specify 'Grd_nj' and 'Grd_overlap'. 'Grd_ni' will get calculated automatically using the following equation:
Grd_ni = ( (Grd_nj - 1) * 3 ) + 1
This means the overlap is 3 times larger on the left and right border of each LAM grid than at the top and bottom! This is done because the solver needs the grids to be 3 times larger in x- than in y-direction (minus 1 point).
An overlap is needed because the two LAM grids will give different answers in the overlap region and the larger the overlap region the easier it is for the solver to find the common solution.
To learn more about Yin-Yang grids have a look at the following wiki page: Yin-Yang grid
LAM grid
Specify the total number of points and the size of the grid boxes in degrees.
If possible, insure that the total number of grid points in x-direction matches the FFT criteria. This will speed up your simulation by up to 10 %.
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