When i set two different fluids, which are air and H2O(l), in CFD-DEM how to define their density?

Dear professors,
I have try to run the process and it worked without error, but its result seems not right. In the spray region is H2O, which were flowed onto the outside of the bed under the inlet air velocity 1m/s. This seems abnormal.

plate.zip (71.3 KB)