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Diaphragm Deflection and Fluid Pressure Modeling using FSI Module in COMSOL 4.1

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I am trying to simulate the pressure rise of the fluid stored in a chamber due to deflection of the top wall (which is also a diaphragm) of the chamber. The other three walls of the chamber is assigned the wall boundary condition. I am using the FSI module in COMSOL 4.1. With a point load of 20kN the top wall (diaphragm) deflects by ~23 micrometers. However, the deflection of the top wall (diaphragm) does not seem to have any effect on the pressure of the fluid held in the chamber. This is incorrect as the liquid should pressurize since it does not have any way to move out of the chamber when the top wall deflects. I also tried with two different fluids, 1) water and 2) air. The deflection of the top wall (diaphragm) in both cases are same. It seems strange since water is nearly incompressible while air is compressible. So with water in the chamber the top wall (diaphragm) should have negligible deflection even in the pressure of the load as opposed to the case with air in the chamber. I am attaching the model along with this post in case any one wants to check it. Could any one suggest a possible explanation/remedy for this?

Thanks.

Bobby.


0 Replies Last Post Jul 10, 2011, 1:27 p.m. EDT
COMSOL Moderator

Hello Bobby Mathew

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