Hi,nThanks for the reply. To check if the particles are settling down due to lower flowrates, I increased the inlet velocity and sure enough the particles are travelling further distance along the channel. This leads me to believe that the particles might have settled down in the original simulation. nBut now, the 20 micron particles are entering and traversing through channels that are 5 microns high. I observed something similar when 5micron particles entered a channel that was 0.5microns high. Is this a numerical error in Fluent and if so can you kindly suggest how it could be fixed?nThanksnn