Extensive model - numbers of cells Vs cell aspect ratio

[David_S]

Hi All,

I am running an external CFD analysis on a large (district size) model. The size of the grid is about 400x300x120m, the geometry is rather conceptual.

The problem I have is that in order to keep the cell aspect size ratio below 50, I would have to refine the mesh to 0.12m. However, this gets me to an absurd number of cells (over 800mio). While I have plenty of RAM (running on a server, currently 26GB RAM just for the IES VE available), in my understanding MicroFlo is a 32bit application and can access only up to 3.9GB RAM (and manage corresponding number of cells, typically about two orders of magnitude lower). But on the other hand, when I try to keep the number of cells within reasonable limits, I have to increase the cell size to about 20m. The problem then is that the cell aspect ratio grows to 4000:1

Questions:

1/ Is MicroFLo still 32bit application (I think newer versions of IES VE are 64bit, I am running IES 2019)?
2/ What are suitable strategies to deal with the model of this size, i.e. how to keep the balance between the cell aspect ratio and number of cells?

Any comments, suggestions, advice how to approach the simulation welcome

Thanks,

David