Numerical evaluation of stresses acting on particles in high-pressure microsystems using a Reynolds stress model

In the present study a model was developed which enables to calculate the stress acting on particles induced by the fluid flow in microchannels. Computational fluid dynamics (CFD) was used to simulate the flow field in five different microchannel geometries. With the help of a Reynolds-stress model and a stationary particle tracking a quantification of stresses in different geometries at varying pressure differences is possible. Furthermore, the effect of cavitation which occurs if the fluid expands to ambient pressure was investigated. The mass flow rates determined by the simulations are in good agreement with the ones determined experimentally. Except for the z-channel the computed stresses are in good agreement with previously conducted dispersion experiments. Additionally, the computed fluid stress was compared with the calculated Kolmogorov length scale to validate the results.