USE OF LATTICE-BOLTZMANN METHOD IN MASS TRANSFER FOR THE WALL SHEAR STRESS CALCULATION IN AN UNSTEADY LAMINAR FLOW DOWNSTREAM OF A CYLINDER LOCATED IN A 2D RECTANGULAR CHANNEL

摘要

A Lattice Boltzmann method (LBM) is proposed to study the flow and mass transfer in the parietal zone of a channel containing a blocking circular obstacle at low Reynolds number. For such configuration, the variation of Re based on cylinder diameter leads to different regime that fluid may occur during it flowing. Hence, this varied behaviour of flow downstream of the obstacle affects the mass transfer rate in the parietal zone of the channel.A sensor with zero concentration on the surface is placed at different locations on the channel wall downstream of the cylinder. Flow velocity and concentration profile of diffusing species on the sensor were evaluated and analyzed for different Reynolds. The Sherwood numbers are calculated and compared with available experimental data.For the present simulation, LBM is based on the D2Q9 lattice model and the single relaxation time approach called BGK method.The challenge of this work is to extend the use of the mesoscopic method (LBM) for a flow problem to studying the enhancement of the rate of mass transfer to channel wall downstream of the obstacle. The numerical results are in good agreement with the benchmark result available in the literature. The highlight of calculation is the flexibility to deal with the boundary conditions for such a problem. The result indicates that LBM is useful for simulation of fluid flows with mass transfer as well as heat transfer.