Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
kb:nesting [2018/07/29 20:44] – [The Role of Nesting Grids] enviadmin | kb:nesting [2018/07/29 20:52] – [Handling of Radiation in the Nesting Area] enviadmin | ||
---|---|---|---|
Line 4: | Line 4: | ||
Practically you don't need them. You can restrict your simulation to the main (core) area without adding any grids as nesting area. \\ | Practically you don't need them. You can restrict your simulation to the main (core) area without adding any grids as nesting area. \\ | ||
- | The problem | + | |
+ | **In times of large computation power, we recommend to not use Nesting Grids anymore but to include more grid cells at the borders within the " | ||
+ | |||
+ | However, there a still situations where the Nesting Grids can help you to improve the model results (or make the model stable) | ||
+ | |||
+ | The reason why Nesting Cells are an option in ENVI-met | ||
The reason for these problems is resulting from the fact, that the model cannot calculate real values for grid points along the borders (and especially not for grid points that are the border). As these points are missing at least one neighbour grid, only simple assumptions can be used here to obtain values that can be used in the model. This simple assumption can be that the values are constant at these grid points (so called //closed boundary conditions// | The reason for these problems is resulting from the fact, that the model cannot calculate real values for grid points along the borders (and especially not for grid points that are the border). As these points are missing at least one neighbour grid, only simple assumptions can be used here to obtain values that can be used in the model. This simple assumption can be that the values are constant at these grid points (so called //closed boundary conditions// | ||
Line 44: | Line 49: | ||
===== Handling of Radiation in the Nesting Area ===== | ===== Handling of Radiation in the Nesting Area ===== | ||
- | As no buildings are present in the nesting area, the sun radiation can reach the surface without reduction. This might result in an unrealistic overestimation of the surface temperature in the nesting area, especially when only sealed surfaces are used as soil profiles. To overcome this problem, ENVI-met can use radiative values averaged over the main model area instead of the normal radiative fluxes in the nesting area. To enable this function, | + | As no buildings are present in the nesting area, the sun radiation can reach the surface without reduction. This might result in an unrealistic overestimation of the surface temperature in the nesting area, especially when only sealed surfaces are used as soil profiles. To overcome this problem, ENVI-met can use radiative values averaged over the main model area instead of the normal radiative fluxes in the nesting area. This function |
---- | ---- |