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How to model a sharply changing BC
Posted 26 mar 2019, 03:48 GMT-4 Ray Optics, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 5.4 0 Replies
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Ok, so I have a laser source that turns off at a particular point in time. I need to model the laser, heating and heat distribution until it completely cools off. I can do this with multiple steps however it makes it impossible to do a parameter/auxiliary sweep (As far as I know). So I want to use a variable BC, but I think COMSOL sees high gradients and decides that it needs to turn it off sooner and in steps (Without telling me, I might add). Is there anyway to model this? I thought a shorter time-step might allow me to achieve this. However,the duration is too long to reduce timestep for the whole run and COMSOL simply ignores my variable timesteps (example below) and only uses the initial value of the function throughout the simulation.
Timestep Function Example (ignore the fact that it is needlessly complicated):
1(0.25(t[1/s]<(Duration-20))+0.75(t[1/s]<(Duration-10)))+(0.05(t[1/s]>=(Duration-10)))+0.95*(t[1/s]>(Duration+10))
P.S. Maybe I should mention that by timestep I actually mean the "Study Settings>Times" section.
Hello Pooyan Heravi
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