Influence of wall roughness models on fluid flow and heat transfer in microchannels

• A new roughness model is proposed and compared with others in both 2D & 3D.
• Gauss model is more flexible and convenient in practice than the fractal model.
• 2D model of roughness is unacceptable to describe the real rough surface.
• Roughness is positive on the thermal performance in microchannels.

To disclose the fluid flowing and thermal performance in microchannels with roughness, a novel and effective rough surface model, Gauss model, was proposed and the comparing investigation with other typical models of both 2D and 3D proposed in literature, especially the fractal model, were carried out. The 2D roughness model, whatever regular model or random model, are found failure to reveal the effect of roughness on fluid flow and heat transfer accurately since the 2D model is incompetent to describe the real rough surface. And the 3D Gauss model both with efficiency and accuracy are presented rather than the fractal model in our paper. By investigation of thermal performance in microchannels, both flow resistance and heat transfer are found sensitive to the surface morphology of microchannels. In general, roughness play a positive role on the thermal performance as well as flow resistance under laminar flow.