Defining a time dependent heat source (Heat transfer)

Sayee Srikarah Volaity

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Hey there,

I am solving a heat transfer problem in which there is a time dependent heat source for a particular domain in the geometry. The heat source to be implemented is:

(1) If the temperature of the element (mesh element of the mesh corresponding to the heat source domain) is below a certain temperature "To", heat source = f(t), where t is the time. (2) If the temperature of the element crosses To, heat source = f(t, to), where to is the time at which the temperature of the element crosses To.

So to define this type of a heat source, I need to know the temperature of each mesh element, the time at which the temperature of the element becomes To.

Would be a great help if anyone can let me know how can I impelement such a heat source function.


3 Replies Last Post Feb 10, 2024, 10:28 a.m. EST
Dave Greve Certified Consultant

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Posted: 3 months ago Feb 4, 2024, 7:44 p.m. EST
Updated: 3 months ago Feb 4, 2024, 7:44 p.m. EST

My guess is that OP doesn't really need to work with individual mesh elements. Most always it is enough to define a volumetric heat source that is a function of local temperature. Without more details I don't immediately see how to implement the dependence on the time the temperature crosses a threshold, although I suspect state variables might be a way to do handle this.

My guess is that OP doesn't really need to work with individual mesh elements. Most always it is enough to define a volumetric heat source that is a function of local temperature. Without more details I don't immediately see how to implement the dependence on the time the temperature crosses a threshold, although I suspect state variables might be a way to do handle this.

Edgar J. Kaiser Certified Consultant

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Posted: 3 months ago Feb 5, 2024, 3:13 a.m. EST
Updated: 3 months ago Feb 5, 2024, 4:42 a.m. EST

Hi,

I understand that you want to determine the time for each location when a certain temperature threshold is reached. You need to implement an additional equation for this. This blog post by Walter Frei may help: https://www.comsol.com/blogs/using-the-previous-solution-operator-in-transient-modeling/

Cheers

Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi, I understand that you want to determine the time for each location when a certain temperature threshold is reached. You need to implement an additional equation for this. This blog post by Walter Frei may help: Cheers Edgar

Sayee Srikarah Volaity

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Posted: 3 months ago Feb 10, 2024, 10:28 a.m. EST
Updated: 3 months ago Feb 10, 2024, 10:26 a.m. EST

Hello Dave and Edgar,

I was able to fix the issue by using state variables and some conditional statements. The blog on using the previous solution operator was useful too.

Thank you!

Hello Dave and Edgar, I was able to fix the issue by using state variables and some conditional statements. The blog on using the previous solution operator was useful too. Thank you!

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