A New Method of Roughness Construction and Analysis of Construct Parameters

In micro-manufacturing, roughness is unavoidable due to the tolerance of micro-machining methods. Roughness in microchannel could have a significant influence on flow and heat transfer since the size of microchannel is very small. In our work, roughness is modeled as a superposition of waves. A simple Fourier series method is proposed to construct the rough surface. With this method, roughness is constructed on the bottom of the rectangular microchannel which has a hydraulic diameter of 0.5 mm. Two important parameters during roughness construction, triangulate size and correlation length are studied under the same relative roughness 1%. Results show that flow and heat transfer characteristics are not sensitive to triangulate size. While triangulate size is changing from 0.1 mm to 0.05 mm, the variations of pressure drop and average Nusselt number are less than 1%. Correlation length could influence the topography of roughness surface a lot, smaller correlation length will lead to more pressure drop and lower Nusselt number.