Analytical and numerical calculation of the detachment of particle structures from fibers

摘要

Not much research has been done on the detachment of deposit structures from fibers in gas flow.This study presents two approaches to determine the fluid velocities uc required for detachment.The first is an analytical model based on the imbalance of drag and adhesive forces.With the help of available models in literature two curves for uc as a function of deposit diameter were calculated.The two curves represent the different conditions present in a deposited structure,consisting of a mixture of reactive and inert matter,before and after reaction.It approximates the structure by one sphere,that consists of two identical half spheres,of which one detaches due to drag.The second approach is a CFD model,in which the deposited particle structure is represented through an immersed boundary method(IBM).It calculates adhesive forces based on the van der Waals force between two half-spaces,while drag is directly evaluated from flow properties at the structure's surface.To be comparable with the analytical approach,it also approximates the deposit with two half spheres.The models are capable of describing detachment velocity behavior as a function of deposit structure size and porosity as reported in literature.