多孔介质壁面条件下微尺度流动的数值模拟

Numerical simulation for micro-scale flow field with porous medium model

利用多孔介质模拟微通道壁面粗糙元,建立了一种新的微尺度化流场的数值模拟方法.多孔介质模型厚度由微通道壁面相对粗糙度折算,多孔介质的阻力系数由该区域内的流态及阻力计算;配合采用k-ε和k-ω多种形式的湍流模型,对边长为600μm的方形断面微通道流场在雷诺数分别为100和300的情况下进行了数值模拟计算.通过模拟结果与Micro-PIV测量数据的对比分析发现,采用realizablek-ε湍流模型,搭配多孔介质微尺度化模型进行数值计算,能够有效地模拟微尺度流场的流动状况,而标准k-ε湍流模型和RNGk-ε湍流模型的微尺度模拟计算结果虽接近试验测量值,但仍有偏差;标准k-ω湍流模型和SSTk-ω湍流模型的微尺度模拟效果较差.

A novel numerical method for simulating micro-scale flow field was established mainly by adopting porous medium model to simulate wall roughness elements.Thickness of porous media was converted by the wall relative roughness,and drag coefficient was determined by flow state as well as resistance of porous media.Under Reynolds number of 100 and 300 respectively,various models were applied to simulate the flow field of square-section micro-channel with side length of 600 μm.Comparison between results of simulation and those of Micro-PIV experiment indicated that,realizable k-ε turbulence model combining porous medium model was most effective for micro-channel flow field simulation,while standard k-ε turbulence model and RNG k-ε turbulence model gave results close to experimental ones with somehow deviations.However,standard k-ω turbulence model and SST k-ω turbulence model exhibited much poor capability in such micro-scale simulations.