How to check if a cell is a full cell or cut cell in the mfix_usr_reactions_rates_K.H?

MFIX-Exa
1

Need to check the overconsumption in each cell for a case with csg.
Is there a way to check whether a cell is a full cell or a cut cell in the mfix_usr_reactions_rates_K.H ?
And how to get the cell volume of the cut cell in the mfix_usr_reactions_rates_K.H?

2

Currently checking if a cell is covered or cut is not supported in mfix_usr_reactions_rates_K.H but it can be added if needed.
You can get cell volume and volume fraction by respectively reactions.cell_volume() and reactions.vfrac() in either eulerian or lagrangian reaction rates

3

Thanks Roberto, can reactions.cell_volume() get the cell volume of a cut cell?

4

To get the volume of a cut cell you need to multiply cell_volume by vfrac, aka:

amrex::Real effective_cell_volume = reactions.cell_volume()*reactions.vfrac();
1 Like
5

Isn’t just checking if reactions.vfrac() > 1 - small_number what @YupengXu is asking when he wants to check for full (uncut) cells?

6

That might work but it isn’t the most efficient way. I think that if checking whether a cell is cut or regular is really needed in reaction rates, it would be best to just add the needed functions and data to the classes used in chemistry.

7

While I’m not strenuously opposed to making cell flag data available to the reactions UDF, I think it may encourage bad practices in implementing reaction rate expressions. Specifically, reactions should not be treated differently in cut-cut cells (i.e., !flag(i,j,k).isRegular()).

1 Like