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Switching conditions on/off with Step or Rectangle
Posted 9 nov. 2010, 04:59 UTC−5 Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.2 3 Replies
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Hi !
I'm using Comsol Version 4.0a
I have a heat source for a domain that I want to switch on for some milliseconds and then switch off.
In Parameters I have defined a constant called Heat and given it the correct value and denomination (W/m^3)
When using the step function I get the temperature of the domain to the correct temperature, but ot turned off the heat.
I defined the heat source as step(t)*Heat
Tried to use the Rectangle function, but now the temperature of the particle will not rise, using the following equation as heat source Rect(t)*Heat
Also I get the yellow text in the heat source field with the "Unexpected unit of input" even though this should be correct.
Any tips would be greatly appreciated
Thanks
Nils Eivind
I'm using Comsol Version 4.0a
I have a heat source for a domain that I want to switch on for some milliseconds and then switch off.
In Parameters I have defined a constant called Heat and given it the correct value and denomination (W/m^3)
When using the step function I get the temperature of the domain to the correct temperature, but ot turned off the heat.
I defined the heat source as step(t)*Heat
Tried to use the Rectangle function, but now the temperature of the particle will not rise, using the following equation as heat source Rect(t)*Heat
Also I get the yellow text in the heat source field with the "Unexpected unit of input" even though this should be correct.
Any tips would be greatly appreciated
Thanks
Nils Eivind
3 Replies Last Post 18 sept. 2016, 06:06 UTC−4
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Posted:
1 decade ago
"Case closed"
Got it solved it by "thinking opposite" - turn off heat source instead off turning it on and then off again.
Got it solved it by "thinking opposite" - turn off heat source instead off turning it on and then off again.
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Posted:
1 decade ago
Great!
Just a note about the unit warning: Functions expect dimensionless inputs and outputs, so you can eliminate the orange color and the "unexpected unit of input" warning by making t dimensionless using [1/s]:
Rect(t[1/s])*Heat
Magnus Ringh, COMSOL
Just a note about the unit warning: Functions expect dimensionless inputs and outputs, so you can eliminate the orange color and the "unexpected unit of input" warning by making t dimensionless using [1/s]:
Rect(t[1/s])*Heat
Magnus Ringh, COMSOL
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Posted:
8 years ago
Hi
using the version 5.2, in the variable expression i try to use sinh(phi) or cosh(phi) and give them a name , the unit of (phi) is the volt wich is the variable of electrostatic module, but the color is orange and show ''unexpected unit of input'' so i can't use it in boundary condition ad i can't solve my problem
Appreciate much for your help!!
using the version 5.2, in the variable expression i try to use sinh(phi) or cosh(phi) and give them a name , the unit of (phi) is the volt wich is the variable of electrostatic module, but the color is orange and show ''unexpected unit of input'' so i can't use it in boundary condition ad i can't solve my problem
Appreciate much for your help!!