随机粗糙微通道内部流动与传质特性

Flow and Mass Transfer Characteristics in Random Roughness Surface Microchannels

为了研究微通道壁面随机粗糙度对流体流动和传质特性的影响,采用随机排布准则构建具有典型粗糙元类型的随机粗糙微通道壁面,利用有限元方法分析壁面随机粗糙度对流速、压降、流动阻力和传质性能的影响,并给出粗糙微通道内部Poiseuille数和分子传质扩散的近似变化规律。结果表明,流体在粗糙微通道近壁面区域和主流区的流速差异较大,近壁面区域流动分离现象明显;与光滑微通道相比,粗糙微通道内部各位置的压降和Poiseuille数沿着流动方向呈近似线性增大趋势;微通道壁面粗糙度的存在可以强化流体分子的传质扩散速率,但受粗糙度类型和相对粗糙度的影响较大。

In order to study the effects of random roughness on the flow and mass transfer characteristics of the microchannel walls,the random roughness of the microchannel walls with typical roughness was established using the random arrangement criterion. The effects of random roughness on velocity,pressure drop,flow resistance and mass transfer characteristics were analyzed by finite element method,and the approximate variation law of Poiseuille number and molecular diffusion in rough microchannels were given.Results show that the flow velocity of the fluid in the near-wall areas and the mainstream regions of the coarse microchannels is quite different,and the flow separation in the near-wall areas is obvious.Compared with the smooth microchannels,the pressure drop and the Poiseuille number in each positions of the microchannels increase linearly along the flow direction. The existence of the microchannel wall roughness accelerates the diffusion rate of fluid molecules mass transfer,butit is greatly affected by roughness type and relative roughness height.