transient heat flux and temperature analysis

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Mihir Velani

Mihir Velani

February 13, 2013 8:38am UTC

transient heat flux and temperature analysis

Dear all,
I am very new to COMSOL multiphysics.
I am doing a transient thermal analysis on geometry containing ceramic and aluminum blocks.
for the boundary conditions I need to define volumetric heat generation with respect to time, rest of the other boundary conditions like convection and initial temperature are constant.
As a result of this I want to see temperature and total heat flux for a transient having a microseconds scale.

Please help me....

appreciate all kind of help

Mihir

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Ivar Kjelberg

Ivar Kjelberg

February 13, 2013 1:28pm UTC in response to Mihir Velani

Re: transient heat flux and temperature analysis

Hi

as for any other model, you need to start and proceed the same way: geoemtry, materials, physics, BC's then mesh and solve, and final postprocessing.
Now "bounday" setings are required for typically initial and fixed temperatures and sources, but a "volume source" is a domain condition and not really a "Boundary condition"

Note also that, if you are in any other size than MEMS dimensions (<1mm) then micro-second themperature effects are not really frequent and expected, fromm my knowledge (except perhaps if you are dealing with chemistry and rapid chemical reactions)

--
Good luck
Ivar

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Mihir Velani

Mihir Velani

February 14, 2013 3:44am UTC in response to Ivar Kjelberg

Re: transient heat flux and temperature analysis

Thank you Sir,

for your reply.

The matter is the volumetric heat generation varies with time...for example( the transient is of 0 to 50e-06 seconds)- at 1.26E-06 seconds, it is 4e12 w/m3 and 50e-06 seconds, it is 1e10 w/m3... and for this I want to check total thermal flux and temperature variation as output.

You are requested to direct me for this and if possible sir, please mention the steps..

I am deeply re grated for your inconvenience.


Regards,
Mihir

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Ivar Kjelberg

Ivar Kjelberg

February 14, 2013 1:57pm UTC in response to Mihir Velani

Re: transient heat flux and temperature analysis

Hi

you need to define your heat shape via an analytical or a combination of step, rectangle or ramp function (Definitions - Functions, then use the correct (t[1/s]) argument when calling your function in the BC or domain variable field, and set up stepping range values such to cover your transitions and it should go.

Last: check your solver "stepping" settings and do NOT use automatic, but try intermediate or strict, check the doc

--
Good luck
Ivar

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