Hello, I simulate the gas/solid flow in which the volume fraction of the solid phase in the inlet is 2.5e-06. The solid phase volume fraction in the vessel will reach up to 0.4. I select the Eulerain model and use the unsteady method to calculate the flow, but I find some problem in the simulation.

I find the trend of the volume fraction is different from the experiment. When several seconds having been calculated, the result show that in the places where the solid phase has not reached the volume fraction is about 3.5e-6-06, which is higher than the place the solid has reached. But when I increase the volume fraction in the inlet, the trend of the volume fraction distribution is right. I cannot find the reason for the phenomenon. Does the Eulerian model have lower limit to the volume fraction? Does the volume fraction of 2.5e-06 have exceeded the lower limit? Any advice is appreciated. Thanks in advance.

are you using the double precision solver?

yes,i use the double precision solver.