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Simulating a rheometer

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Hi Everyone,
I'm a bit new to Comsol so sorry if this is a dumb question. I'm trying to simulate a rheometer in my lab. It's basically a cone in a petri dish. For simplicity I'm using 2-D and have parallel plates. Now the problem I'm having is that when I try running the simulation with the far boundary as a wall it keeps crashing but is fine when I use an open boundary. Based on the actual circumstances I want to use a wall since that is the edge of the petri dish. Does anyone have ideas as to why this is happening and how to fix it?
Thanks for the help!


1 Reply Last Post Jul 26, 2013, 9:19 a.m. EDT

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Posted: 1 decade ago Jul 26, 2013, 9:19 a.m. EDT
Hi,

You need to use a time-step function so that the wall velocity goes from zero to the desired values in a finite interval of time, also you need to introduce a pressure point constraint since you have no inlet nor outlet.

Please find attached the modified model.

Cheers
Hi, You need to use a time-step function so that the wall velocity goes from zero to the desired values in a finite interval of time, also you need to introduce a pressure point constraint since you have no inlet nor outlet. Please find attached the modified model. Cheers

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