绕流具有光合生化反应管束的格子Boltzmann模拟

采用格子Boltzmann方法模拟了有机废水溶液绕流表面附着有光合生物膜管束的流动、传质及光合生化反应过程，并分析了管束排列，管间距及Reynolds数对流场、浓度场、平均阻力系数及底物的Sherwood数的影响。结果表明：溶液绕流小管间距时具有较高的Sherwood数，同时阻力系数也较高；与顺排管束相比，绕流叉排管束的平均Sherwood数增大了一倍左右，其增大幅度随Re的增大而增大，而阻力系数仅增大了约10%。一定条件下，绕流叉排管束时，出口处具有较低的底物浓度和较高的产物浓度。结果表明，很小的流场扰动可对浓度场产生较大影响，从而，叉排管束更有利于传输传质及生物降解。

Lattice Boltzmann simulation of substrate flow past tube bundle with photo-biochemical reaction

The lattice Boltzmann method is applied to simulate the fluid flow and mass transfer accompanying biochemical reaction,which is a bio-hydrogen production system by photosynthetic bacteria in biofilm adhered on the surface of tube bundle.The effect of inlet velocity(Reynolds number),tube spacing and tube arrangement(inline and staggered)on velocity and concentration fields,average drag coefficient,and Sherwood number of substrate are investigated.The velocity field and concentration fields of substrate and product under various conditions are depicted.Lower substrate concentration and higher product concentration are obtained at the rear of tubes,both for inline and staggered arrangement. Compared to that with inline arrangement,the substrate concentration is lower and product concentration is higher at the outlet for solution fluid flow around staggered bundle.Furthermore,the hydrodynamics and mass transfer are estimated by parameters of average drag coefficient and Sherwood number of substrate.The numerical results reveal that small tube spacing leads to high Sherwood number of substrate,but at the expense of high drag coefficient.Compared with inline arrangement,the staggered arrangement leads to an up to double increment in Sherwood number and the increment increases with Re,while drag coefficient increases only 10%.It is concluded that small fluid disturbance has a great impact on the mass transfer,and the staggered arrangement is more beneficial to mass transfer and biodegradation.