Main modes of microfilament particles deformation in rough channels

Abstract

The fate and transport of microfilaments in complex structured porous systems are largely affected by the geometry of the irregular pore space in these media. Local features of fluid flow, including local flow instabilities, vorticities, stagnant zones, and reverse flows, which result from the spatially varying pore throat size and altering shear stresses along the channel due to the presence of rough walls, can cause various modes of deformation of filaments and them being carried in reverse direction of the general fluid flow. Furthermore, the buildup of microfilaments along the channel can clog the pore space and rearrange the flow in the channel. In this study, we focus on investigating the role of channel wall roughness on the motion and deformation of five deformable filaments flowing in a channel filled with fluid. A bead-spring model is used for the filament model. At low Reynolds numbers, roughness simply increases the length of the path line along which the filament is being transported. Moreover, at higher Reynolds numbers, the filament closer to the walls can get stuck in the dead flow zones within the rough geometry peaks. The filaments closer to the centerline of the channel undergo less deformation compared to those located closer to the walls. A larger Reynolds number or a more rough geometry of the walls can result in a more wiggly form of the filament. Intermediate roughness and a medium Reynolds number result in more of a hairpin-like filament shape.