Effect of wall roughness on laminar flow of bingham plastic fluids through microtubes

The flow characteristics of liquids modeled by the Bingham plastic constitutive relation through microtubes were numerically studied. The wall roughness effect in a microtube was characterized by using a roughness-viscosity model. The model was used to modify the laminar Bingham plastic flow equations in microtubes by introducing a location dependent apparent viscosity. The results show that the flow friction in microtubes is considerably larger than the predictions of the conventional theory based on uniform viscosity.