(124g) Assessment of Mesoscopic Particle-Based Methods for Simulation of Complex Fluids in Microfluidic Geometries

We assess the accuracy and efficiency of mesoscopic simulation methods, namely Stochastic Rotation Dynamics (SRD) and Dissipative Particle Dynamics (DPD), for flows of complex fluids, such as polymer solutions, through microfluidic geometries.  Since both SRD and DPD use soft or weakly interacting solvent “beads” to carry momentum, both methods contain unwanted particle inertial effects, and high fluid compressibility. To assess these effects, we compare the speed and accuracy of predictions of SRD and DPD for computing flow in a straight channel with periodic slip boundary conditions, representing a periodic electroosmotic flow, which is a complex flow with an analytical solution for low Reynolds number. We find that SRD is roughly ten-fold faster than DPD in predicting the flow field, with similar accuracy at low Reynolds number.  However, SRD has more severe problems with compressibility effects than does DPD, which limits the Reynolds numbers attainable in SRD at reasonable computational cost to Re < 100, while DPD can achieve Re higher than this before compressibility effects become too large.  The results help determine the range of conditions for which SRD or DPD is preferable for mesoscopic simulations.