عنوان مقاله [English]
In the present study, a laminar pressure-driven flow within a microchannel consisting of two parallel flat plates with rugged walls has been simulated. Walls ruggednesses have sinusoidal profiles with relative heights of 0≤h/H≤0.15. The main purpose is the determination of differentiation boundary of surface roughness and wall blocks. The flow governing equations in a system of two-dimensional general coordinates are solved using finite-volume numerical method in a non-uniform grid with maximum orthogonality of grid lines adjacent to rugged boundaries. In the first step, the surface ruggednesses of wall are divided into two categories: “surface roughness” and “wall blocks”. Then, the differentiation boundary of surface roughness from wall blocks is determined by applying two qualitative and quantitative criteria. According to the qualitative criterion, when the surface ruggedness is surface roughness, the pressure distribution at the centerline remains as linear as a perfectly smooth microchannel. But when the surface ruggednesses are wall blocks, however, the pressure distribution at the centerline is oscillating. Also, on the quantitative criterion, the average shear and normal forces just adjacent to the rugged surfaces are calculated and compared for different relative ruggednesses. According to the results, in the laminar flow within the rugged planar microchannels, firstly, ├ h/H┤|_cr is 0.042 which is independent of Δp. Secondly, the surface roughness affect the flow dynamics and increase the friction factor and decrease the flow.