فهرست مطالب فرهود شیرین زاده

Solid particles migration in liquid phase through microchannels is considered to be the most important issue in microfluidic systems. Converging-Diverging microchannels are being used in manufacturing the microfluidics tools such as micro-switches, micro-sensors and micro-filters. In this research, 3-D numerical simulation based on Eulerian-Eulerian approach was performed on solid-liquid two-phase flow in a converging-diverging microchannel with 200 μm height. The size of particles used in this research is 20μm with density of 1.05 gr/cm3. The results showed that the most particle accumulations occured in the regions close to the walls before and after the nozzle, but in the converging part of the nozzle, the amount of particles even near the walls decreased due to the increase in flow velocity. Furthermore, increasing the Reynolds number leaded to increase in the amount of particles accumulated at the throat and reached its maximum value. Compared with similar studies, this study investigates the effect of converging-diverging geometry of the channel on particle sedimentation. The results show that using converging-diverging channel provides the possibility to prevent the destructive phenomenon of channel blockage.

In this research, 3-D numerical simulation based on Eulerian-Lagrangian approach was performed on solid-liquid two-phase flow in a convergent-divergent 200 μm microchannel. The size of particles used in this research is 20, 40 and 60 μm with density of 1.05 gr/cm3. Results include velocity domain of the particle at the channel cross section, Reynolds No. effect on particle velocity, particle diameter effect on particle velocity, and the effect of top-down and side walls on particle velocity. The numerical results show that in addition to the top-down walls, the side walls also reduce the velocity of the particles in the direct microchannel up to 42%. Compared with similar studies, the effect of channel convergence on particle deposition is investigated in this study. The results show that the convergent-divergent part of the microchannel reduces particles sedimentation up to occurs 45% comparing with direct part of the microchannel due to particle acceleration, which is one of the benefits of convergent-divergent microchannels.