CFD simulations of turbulent flow in baffle-filled membrane tubes

Computational fluid dynamics (CFD) simulations were carried out for fluid flow in baffle-filled membrane tubes, in which an array of central baffles or wall baffles was inserted. The commercial CFD package FLUENT, which employs the finite-volume method, was used for numerical computations. Through CFD simulations, the qualitative and quantitative properties of fluid dynamics in a baffle-filled channel can be obtained, which benefits to fully understand the effects of two types of baffles on flow pattern, behavior and feature. The simulation results show that the presence of baffles causes remarkable increases of the average velocity and shear stress on the tube wall, which can significantly improve the filtration performance. The flux enhancement is also attributed to the intense fluctuations of wall velocity and wall shear stress, which can greatly disrupt the development of boundary layer, as well as the growth of cake layer. The experimental results of crossflow microfiltration of calcium carbonate suspensions are consistent with the CFD simulations. However, the pressure drop along the baffle-filled membrane tube is significantly increased owing to the frequent changes in flow direction and the energy dissipation of turbulent flow.