Numerical Simulation of First-Order Surface Reaction in Open Cavity Using Lattice Boltzmann Method

The lattice Boltzmann method (LBM) is a finite element and finite volume method for studying the reaction rate, mass diffusion and concentration of species. We are used the LBM to investigate the effect of the Damköhler number (Da) and Reynolds number (Re) on the laminar flow in a channel with an open square cavity and a reactive bottom wall in two dimensions in a first-order chemical reaction. The reactant A is transported through the cavity, where it undergoes a reaction on the reactive surface, resulting in the synthesis of product B. The effect of Da < 1 on the reaction rate is negligible for all investigated Re values; the generation of product B is slower because of the effect of the momentum diffusivity on the velocity inside the cavity. For Re = 5 and 1 < Da ≤ 100, the concentration of B inside the cavity reaches the maximum for Da = 100, and A is absorbed almost entirely on the bottom of the cavity. In our simulations, we observed that for all values of Re and Da > 100, the effect of the momentum diffusivity is negligible in the cavity, and the reaction on the surface is almost instantaneous.