# P&K AST (TA Luft 2021 / AUSTAL)

## Computation Grids

Form for the definition of the computing grids. Nothing must be entered in this form, except the grids are not to be automatically determined by AUSTAL. If more then one grid (nested grids) are defined, they must meet the following conditions.

- An enlargement of the mesh size must take place exactly with the factor 2.
- The edges of a fine net must be on the grid lines of the next rougher net.
- A rough net must have at least the dimensions of the next finer net.

The entered data are sorted according to DD and examined then against these rules. DD, X0 and Y0 should have integer values only, in order to avoid rounding problems. These elements can also be placed in Graphical Tools for drawing objects.

### No

Order Number, assignment will change when rows are inserted or tables are sorted.

### Mesh width (DD)

Horizontal and vertical mesh size of the computation grid (default value is the smallest indicated average source height Hq+0.5*Cq, but at least 15 m). The computation grid consists in x-direction of Nx meshes beginning with X0, accordingly in y-direction. If location and expansion of the computation grid are not indicated, then the grid is determined in such a way that for each source a circle with the 50-fold of the average source height does fit inside the computation grid.

### X0, Y0

X0 left (western most) edge of the computation grid; Y0 lower (southern most) edge of the computation grid, see to DD and Z0

### Nx, Ny

Nx number of meshes in x-direction; Ny number of meshes in y-direction, see DD.

### Comment

Describing Text. The Comment will not shown in the Report by default, but can be added in the Setup in the Report.

See also: Operation within the tables