[MovinJ]

Hi,

I'm trying to run a transient simulation that is of a cyclonic separator for a chemical separation project. I'm trying to see the effectiveness of this separator with aerosol-type droplets, and so have modelled the liquid state chemical (NH3), that needs to be separated from the gas, as a dispersed solid with mean diameter of 50 microns. I have turned buoyancy on and have also applied a solid pressure model so that the droplets once fallen to the bottom don't become packed on top of each other.

I also included a drag coefficient model (the Gidaspow model) as this is the behaviour that I'm most interested in to see, how it interacts with the gas and gets separated due to circular motion. However, the solver keeps failing and refers to the "Droplet|Syngas. drag coefficient" as the defective variable and the error type is ENFORCE BOUNDS.

I have had a look at the theory guide for CFX and it seems that the gidaspow model has good definitions for volume fractions between 0-0.8 and 0.8 to 1, but it apparently "Linearly interpolates" between the two functions when the value is between 0.7 and 0.8, my intuition at the moment is this is what's causing it. But I really don't know for certain.

Something to note is that the solver solves very well for the first few fractions of seconds, maybe 60-70 timesteps, and then fails, and it usually says overflow, but I sometimes see this error too.

Any help on this would be really appreciated, I have been stuck on this for weeks now and it would mean alot to me if there are others out there that have had issues with the Gidaspow model as well, and what was done to fix it.

Many thanks