Asymmetric phenomenon of flow and mass transfer in symmetric cylindrical and semi-cylindrical shallow chambers

摘要

Numerical simulations are presented for three-dimensional flow and mass transfer of semi-volatile organic compounds (SVOCs) in cylindrical and semi-cylindrical shallow chambers (Chambers A and B thereafter). The effects of the Reynolds numbers, ranging from 2 to 1100, on velocity and concentration field are considered in the one-quarter domain, the half domain, and the entire domain of chambers. The results show that at low Reynolds number, the streamline and concentration distribution are unique and symmetric. When Re exceeds the critical Reynolds numbers, Rec, asymmetric flow and mass transfer occur in Chamber A in the Y-planes and Chamber B in both the Y- and Z-planes. The critical Reynolds numbers in Chamber A and B are 952 and 1054, respectively. At Re = 1013, steady symmetric and asymmetric solutions are both obtained in Chamber A, and the asymmetric convective mass transfer coefficient increases by 1.52% compared with the symmetric result. The asymmetric convection in Chamber B decreases 3.45% of the Sherwood number than the symmetric flow. As the Reynolds number increases, the mass transfer efficiency increases in both chambers. The velocity field from the special structure of Chamber B leads to a stronger convective mass transfer.