Numerical analysis of pressure drop reduction of bubbly flows through hydrophobic microgrooved channels.

Due to the high performance of hydrophobic surfaces in pressure drop reduction, they have been proposed for various applications. However, despite the extensive uses of two-phase flows in many industries, the effect of hydrophobic surfaces on the pressure drop reduction of two-phase flows has not been well understood yet. Thus, in the present study, by implementing the phase-field and finite element methods, the bubbly flows as an example of two-phase flows are considered for examining the effect of hydrophobic microgrooved microchannels on the pressure drop reduction of these regimes in the laminar state. We found out that hydrophobic microgrooved surfaces not only can be efficient in the bubbly flow but also can even cause a maximum pressure drop reduction of up to 70%, which is almost 3.5 times higher than in single-phase flow. We also studied the influence of each parameter, such as bubbles volume or length, Reynolds number, capillary number, and their combination on this phenomenon. The pressure drop reduction grows by increasing the volume of the bubbles but decreases by increasing the flow velocity or the surface tension coefficient. The combination of these parameters demonstrated different results in some circumstances.

Design and simulation of a novel integrated microfluidic chip for cell isolation and culture.

The lab on a chip is utilized as a background and a substrate for creating a proper flow for cellular processes in medicine. In this study, the concepts of cell isolation and cell transfer methods have been discussed. After that, the device of separation and transfer systems has been designed, simulated, and verified by placing the frequency of particle separation and droplet formation, which is tried to introduce a new device that can be used in cellular studies. The optimal operation conditions for the problem have also been investigated. High separation efficiency (99%) could be achieved when the velocity of the sample inlet in the microchannel separator is 180 µm/s. Also, a microfluidic device for droplet generation has been designed to transfer the isolated cells to the culture medium. For this purpose, the frequency of droplet production must be synchronized with particle ejection frequency and equals 9.09 Hz.