Systematic Assessment of Roughness Effect on Flow Characteristics in Minichannels

Flow through minichannels is of major importance in many industrial applications. Submillimeter length scales of such domains and presence of roughness make the flow analysis a challenging task. In order to investigate friction factor in the minichannel, both numerical methods and in-house experiment are employed. First, flow over a rough flat plate is studied numerically to check the accuracy and performance of employed numerical models. Subsequently, flow in a minichannel with submillimeter height and different surface quality is studied. The test stand makes it possible to investigate the pressure drop in a wide range of Reynolds numbers. In the numerical simulations, equivalent sand-grain roughness is considered and implemented by an artificial increase in the turbulent viscosity on the wall based on this value. Good agreement between the numerical results and experimental data represents the accuracy of utilized models and methods. Roughness increases the friction factor in minichannels and this growth is more visible in higher Reynolds numbers and turbulent flows.