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High pressure and recirculations using Laminar Two-phase flow module

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Hi,

I am trying to use the Laminar two-phase flow, phase field module to simulate the process using water to displace gas. The geometry is shown in the attached figure, 50 microns in height and 10 microns in width with a microstructure on one side to simulate micro-roughness. In the figure, the "volume fraction" shows the initial and final states of gas volume fraction, the "pressure distribution" shows the pressure contour at the final stage, whereas the "flow streamline" shows flow pattern inside the micro . I set a constant inlet pressure as 12000 Pa. I have two questions regarding this simulation.
1. Why can high pressure, around 80000 Pa, be observed in the trapped gas? It is much higher than the injection pressure. In the equations, I used incompressible fluids, and the NS equation is the only one that has pressure in it.
2. Since I used the laminar module (very low Reynolds number), how to explain the recirculation occurs in the micro-roughness?
Any help would be greatly appreciated.

Regards,
Albert


0 Replies Last Post Feb 16, 2016, 12:17 a.m. EST
COMSOL Moderator

Hello Tianhang Bai

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