Numerical Investigation on Flow Characteristics of Non-Newtonian Fluids in Microchannels with Microcavities

Efficient transport of non-Newtonian fluids plays an important role in energy and thermal management systems. However, drag reduction characteristics and fluid behavior of non-Newtonian fluids in microchannels with structures are still under investigated, which is essential for lowering pumping power, improving transport and heat transfer efficiency to optimize microfluidic device design. This study systematically investigates the drag reduction performance of non-Newtonian fluids in microchannels with various cavities through numerical simulations and experimental verification. The effects of cavity incidence angle, structural smoothness, non-Newtonian rheological parameters, and shape parameters are analyzed. The drag reduction efficiencies under both cavities and non-Newtonian fluids conditions were tested, and found to increase by up to 7.6% at low flow rates, but decrease at higher flow rates. Among all the configurations, isosceles triangular and semicircular cavities exhibit superior drag reduction. Non-Newtonian parameters, the consistency coefficient m and power law index n, both present nonlinear behavior with the pressure drop rate. Geometric parameters, shape ratio, depth ratio, and spacing ratio have little effect on the drag reduction effect. Therefore, our work clarifies the coupling mechanisms of drag reduction between fluid rheology and micro cavities, which provides beneficial guidance for the design of the micro channel for optimizing the transport performances of non-Newtonian fluids.