population balance-mixing in a tank
 

Hi
I am modeling two phase(water-in-oil) multiphase in a tank with Rushton impeller and I face a problem in aggregation and breakage system of my PBM. the problem is that I use discrete method for population balance and I have 7 bins. the bin fractions are not correct. (bin0=.99 and other bins are totally 0.01) I should mention that bin0 is the bin with largest droplet diameter. it seems that breakage doesn't happen in my tank. even I just use breakage without coalescence I saw no change in droplet diameter.
any help will be appreciated