Effect of turbulent cross-flow on suspension layer in micro filtration process

清洁空气和水处理等过滤技术是维持我们现代生活不可或缺的。这些技术的主要机制是通过微孔膜过滤将悬浮颗粒从悬浮液中分离出来。然而，由于膜上的悬浮物（“滤饼”）在膜上堆积，导致压力损失增大，渗透率逐渐降低，这是该技术的关键问题，错流过滤方法是解决该问题的方法之一，该方法将处于湍流状态的悬浮物扫向与膜平行的方向，可以有效地降低过滤过程中的滤饼厚度。本工作阐明，湍流状态可以通过层流湍流转换通过一个小扰动与展向涡诱导。

Filtration technologies such as clean air and water treatment is indispensable to sustaing our modern life. The main mechanism underlying these technologies is that suspended particles are separated from suspension by filteration through a membrane with fine pores. However, the permeability gradually decreases due to an increase in pressure loss caused by an accumulated layer of suspended material, "cake", on the membrane, which is a key problem on the technology.As one of solutions for the problem, the cross-flow filtration method, where suspension in turbulent state is swept to the parallel to the menbrane, can effectively reduces the thickness of cake in the filtration process. The present work elucidates that the turbulent state can be induced via the laminar-turbulent transition via a small perturbation with spanwise vortices.