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Please help me to write different inlet condition with different time?

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I am writing to you from UQTR, Quebec. My work is focused on hydrogen adsorption in a tank containing activated carbon. While charging and discharging hydrogen gas in a tank, I have to give four different inlet conditions of temperature and pressure with different time intervals.

I.e.

x1 at the time of 0s to 1042s, x2 at the time of 1042s to 3181s, x3 at the time of 3181s to 4131s and x4 at the time of 4131s to 6000s.

Here x1, x2, x3, and x4 are different inlet (mass flux) pressure condition.

I am using comsol 4.2 vesion.

Please help me to write different inlet condition with different time?

1 Reply Last Post 2011年9月29日 GMT-4 00:51
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年9月29日 GMT-4 00:51
Hi

there are different discussions how to make such a function, you can either:
1) make a tabular interpolated function (might not give you the steps you expect)
2) or by combining the "Definition Function Step" (v4), this allows for a smoothing function so that your step function remain derivable which helps the solver
3) or you chain three solver sequences, with a bolean expression for your inlet Xn value

Read the doc about the predefined functions, and I expect that you should manage without difficulties
--
Good luck
Ivar
Hi there are different discussions how to make such a function, you can either: 1) make a tabular interpolated function (might not give you the steps you expect) 2) or by combining the "Definition Function Step" (v4), this allows for a smoothing function so that your step function remain derivable which helps the solver 3) or you chain three solver sequences, with a bolean expression for your inlet Xn value Read the doc about the predefined functions, and I expect that you should manage without difficulties -- Good luck Ivar

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