Abstract: A PML model based on fixed surface roughness is used in simulation of surface roughness effect on flow in mini-channels. Compared with 3-D simulation, results of pressure drop agree well. With PML model and 3-D model we simulate different flow rates and roughness, it shows that surface roughness results in speed linear flow substrate. Pressure drop and relative roughness follow a secondary power relation as Re number is fixed. Pressure drop increased linearly with Re number as roughness elements is equal.

Key words: mini-channel, roughness, PML model