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Variable change with time

Posted Jan 18, 2013, 1:47 a.m. EST Version 4.2 2 Replies

Dylan Xia
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I have a question about variable change with time.
I try to make a mass transfer model. The inflow concentration change with time.

If t <= 1000s then C=1mol/m^3
else C=0

I upload the data and make a Interpolation Function. Function name: int1

Then I set the Inlet Concentration as int1. It shows int1 is not variable.

How can I make this kind of variable?

Thanks in advance

Dylan
2 Replies Last Post Jan 19, 2013, 5:01 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 18, 2013, 2:08 a.m. EST
Hi

if you make it a function you need to give it an argument as int1(t[1/s]). But I would propose that you use a step function from 1 to 0 at t = 1000 s with a smoothing of perhaps 1 sec, then enforce your time stepping algorithm to slow down and take a 2-3 points during the switch off (i.e. strict or intermediate stepping)

--
Good luck
Ivar
Hi if you make it a function you need to give it an argument as int1(t[1/s]). But I would propose that you use a step function from 1 to 0 at t = 1000 s with a smoothing of perhaps 1 sec, then enforce your time stepping algorithm to slow down and take a 2-3 points during the switch off (i.e. strict or intermediate stepping) -- Good luck Ivar
Dylan Xia
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Posted: 1 decade ago Jan 19, 2013, 5:01 p.m. EST
Thank you very much.

Dylan
Thank you very much. Dylan

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