Dissipative Particle Dynamics Study On Electroosmotic Flow And Heat Transfer

As one of the most important way for micro flow driving in microfluidic technology and micro-total-analysis-system, the electroosmotic flow has been widely used because it’s simple and efficient. With the development of fluid controlling technique gradually toward complexity and miniaturization, the details and microstructure of internal flow have become the key point to which people pay more and more attention. As a fascinating tool, energy-conserving dissipative particle dynamics(e DPD), which evolved from molecular dynamics(MD), has a great potential to resolve these problems for it’s a lagrangian particle-based method and being more effective and flexible in comparison with MD.However, the emerging and development of e DPD is very short and only a few work focuses on hydrodynamic phenomenon of thermal fluid are reported and the research on multiphysics field couping is more rarely discussed. Therefore, the purpose of present work is to extend the e DPD to model fluid flow and accompanying heat transfer in electroosmotic flow which combined electric field with flow and temperature field. We first describe in detail the control equation of electroosmotic and the theoretical foundation for e DPD simulation and then summarize the general method of multiphysics field couping in e DPD system. After that the flow and heat transfer of pure electroosmotic flow and mixed electroosmotic/pressure-driven flow in simple microchannels are numerical analyzed. by comparison with analytical results or those by FEM, the simulation results prove the correctness of our model.Micro-mixing plays a central role of heat and mass transfer enhancement in micro fluid flow controlling and is of significant importance for miniaturization and integration. In this paper we take into account the effect of the transverse and longitudinal electric field on electroosmotic micro-mixing in a 2D microchannel with nonuniform zeta potential distributions along the channel wall, apply the e DPD method to simulate the flow and heat transfer process and discuss the influence of the pressure gradient and the zeta potential on the stream field and temperature field. The study show that microfluid states under different external electric field are different and the overall effect of electroosmotic micro-mixing and heat transfer will decrease with the increasing of pressure gradient.The induced charge electroosmotic is a kind of new electromotion phenomena which was discovered and designated more than a dozen ago and has not yet been fully understood. Comparing to the classical electroosmotic, it is more efficient and can provide a better driving effect and has attracted more and more attention. For the first time we use e DPD method to simulate the induced charge electroosmotic around a conducting cylinder in the microchannel. The effects of pressure gradient and electrode material on the flow and heat transfer characteristics are examined carefully. It turns out that a complete change or a portion change of the polarizable material on the electrode will deforms the stream field around the electrode. The effect of pressure gradient will be weakened by the electroosmotic vortex on the left side, and be enhanced by the vortex on the other side.This study enriches and strengthens the theory of electrodynamics at mesoscopic scale and manages to extend the e DPD to simulate fluid flow and heat transfer in the multiphysics field couping problem, proves fully the feasibility and flexibility of our method. It can be see that DPD is an reliable numerical method for complex flow and has wide researching foreground.