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How do you set a global definition as a boundary condition?

Posted 3 nov. 2014, 18:02 UTC−5 Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4 1 Reply

Fintan Healy
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HI, firstly I would like to say I am quite new to COMSOL so sorry if the answer to this question is very simple......

For my project I have built a simplistic 2d axis-symmetric geometry (effectively forming a cylinder) and on the top surface I want to define the net inward heat flux as a function of time.

Firstly I have defined a global interpolation function that describes the variation of heat flux with time and have named this function "qt".

Next I have set the boundary condition on the top surface as a general inward heat flux, but I cannot figure out how to define q0 as the function qt(t)

any help would be much appreciated!

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1 Reply Last Post 4 nov. 2014, 19:22 UTC−5
Steve Conrad
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Posted: 1 decade ago 4 nov. 2014, 19:22 UTC−5
At first glance, it appears you have set up the boundary condition correctly. The red color of the int1(t) function suggests you have inconsistent units. To verify this, click on the textbox, and hold the mouse over it to look at the error message. If that is the problem, then you may have to apply a unit operator in the boundary condition, or to set up the correct units in the function definition.

--
Steven Conrad, MD PhD
LSU Health
At first glance, it appears you have set up the boundary condition correctly. The red color of the int1(t) function suggests you have inconsistent units. To verify this, click on the textbox, and hold the mouse over it to look at the error message. If that is the problem, then you may have to apply a unit operator in the boundary condition, or to set up the correct units in the function definition. -- Steven Conrad, MD PhD LSU Health

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