DF envimet - question on the grid

grasshopper dragonfly-legacy
1

Hi @AntonelloDiNunzio, first of all thank you so much for df envimet plugin! I am new to it and I have a question regarding the grid.

01_DF_EV
01_DF_EV1194×766 180 KB

As you can see from the picture, the grid extended 5 cells on the x and y axes (3 on one side and 2 on the other) from the baseSurface, even if I explicitly set addCells and NestingGrids to be 0. The 5 additional cells appear also in the ModelInfo of DFEnvimetSpaces and they count for the 50x50x40 limitation of ENVI-met LITE. However, they are treated differently from grid cells, because DFEnvimetSpaces complains if any object is less than two cells from the grid border, meaning the baseSurface border with no additional cells.

So, are these additional cells like “fixed” in your configuration? are they “normal” cells or nesting grids? Is there a way to control them? I know that a certain space on the border is paramount for a sound CFD simulation, but I am still experimenting with ENVI-met LITE, so each cell counts :wink:

2

Hi @lemar,

It is a behavior of Dragonfly Envimet components. It requires 2 additional cells on the border because of its algorithm to assign materials correctly.I know it is not the best if you have the lite version with grid size limits. Unfortunately, dragonfly envimet components do not have the same principle of Morpho to create the grid where you assign the number of cells directly.

Workaround: make the base_surface a bit smaller, but make sure to have 2 empty cells around the buildings.

In any case, you should have empty border cells for the accuracy of the calculation. Usually it is suggested to add a distance of 3/4 of the highest building.

Best,
Antonello

3

thank you very much for the prompt response! I am implementing the workaround you suggested

regards,
Letizia