Simulation Of Surface Roughness And Processing Fault Effects On Microchannel Flows

In recent years, significant attention has been given to the flow in microchannel due to the rapid development in microfluidic devices and systems. Some experimental results show that the characteristics of microflow are remarkably different from those in conventional sized channels, and the experimental data from different sources may yield different or even opposite conclusions. Although a large pool of experimental data is available, a complete understanding of flow behaviour in the microchannel is still an open problem. The effects of surface roughness and processing fault on the microchannel flow are investingated in present research.Firstly, the surface roughenss is modeled by three kinds of elements, i.e. triangular element, rectangular element and mixed element of triangle and rectangle. The flow fields in microchannel and Poiseuille number are simulated by supposing the surface roughness with above three elements. The numerical results show that the flow field and Poiseuille number are strongly dependent on the parameters of roughenss element such as the element type, the height and length of element and the distance separating two elements. The Poiseuille number is linearly dependent on Reynolds number at low Reynolds number. It is higher than its traditional value of theory.Secondly, the effects of concave holes caused by processing fault on the flow field are studied by introducing the nondimensional parameters. Numerical results show that for single concave hole case, the influenced area of flow field increases when L/ H increases, where L is the cross length of concave hole and channel wall, and H is the half channel height. For the same hole, the influenced area of decreases as Reynolds increases. For two holes case, as the distance between the holes increases, the influenced area increases at first and then begins to decrease. It separates into two the influenced areas of two independent holes finally. At same value,the influenced area is also slightly affected by the volume of concave hole. L/H...