Conjugate heat transfer Interface boundary condition

Topics: 4.3a, 4.3, Heat Transfer

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Anup  Paul

Anup Paul

October 2, 2012 11:25am UTC

Conjugate heat transfer Interface boundary condition

Hello All,

I am new to COMSOL. I am trying to solve a 3-D conjugate heat transfer problem with volumetric heat generation in the solid domain. The problem is more like solving for a temperature profile in a heat exchanger. how and what should be the boundary condition applied for the fluid-solid interface?





rgds

Anup

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Nagi Elabbasi

Nagi Elabbasi
Certified Consultant
Veryst Engineering

October 2, 2012 12:09pm UTC in response to Anup Paul

Re: Conjugate heat transfer Interface boundary condition

COMSOL imposes temperature continuity at the fluid-structure boundary in a conjugate heat transfer problem. There is no need for a different thermal boundary condition there. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection.

Nagi Elabbasi
Veryst Engineering

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Anup  Paul

Anup Paul

October 3, 2012 5:45am UTC in response to Nagi Elabbasi

Re: Conjugate heat transfer Interface boundary condition

thanks ....thanks a lot.




rgds

Anup

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Anup  Paul

Anup Paul

November 4, 2012 11:03am UTC in response to Anup Paul

Re: Conjugate heat transfer Interface boundary condition

Daer Nagi

Its fine that comsol itself taking care of interface boundary condition as heat loss from the solid. However, in my problem the solid is under laser heating (consider as a volumetric heat generation based on Beer-Lambert law)in which i am defining optical properties for solid as well as for fluid such that fluid light absorption characteristic is greater than that of solid. I should get a maximum temperature in the fluid domain not in the solid domain because of higher light absorption characteristic of fluid. But , results shows exactly opposite. The max temp is obtained at the solid domain rather than fluid. If my explanation is correct, how to resolve this issue?



rgds

Anup

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Nagi Elabbasi

Nagi Elabbasi
Certified Consultant
Veryst Engineering

November 4, 2012 6:10pm UTC in response to Anup Paul

Re: Conjugate heat transfer Interface boundary condition

Hi Anup,

Whether solid or fluid gets higher temperature depends also on the distance the laser travels through them as well (not just their absorption characteristics). I don’t think any special treatment is needed at the fluid-solid boundary. You just need to add the volumetric heat source to fluid and solid domains separately.

Nagi Elabbasi
Veryst Engineering

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Anup  Paul

Anup Paul

November 9, 2012 1:20pm UTC in response to Nagi Elabbasi

Re: Conjugate heat transfer Interface boundary condition

thanks


rgds

Anup

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February 15, 2013 5:55am UTC in response to Nagi Elabbasi

Re: Conjugate heat transfer Interface boundary condition


Dear Nagi,

I need an immediate help for the thread : www.comsol.com/community/forums/general/thread/34647/

I am somewhere stuck up in meshing part, thus, request you to please reply.

--
Ishant Jain

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Anup  Paul

Anup Paul

August 7, 2013 11:10am UTC in response to Anup Paul

Time step solution problem reg:

Dear friends

I am solving for transient case for total time of 300secs with time step of 0.1sec [free time step (not strict)].

The time-dependent solver result (for your reference) is attached herewith.

Now under step size, some times it appears "out" and sometimes different values.
What does it mean?


rgds
anup

Attachments:   Time.pdf  

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Jonathan Perez

Jonathan Perez

February 21, 2014 3:08am UTC in response to Nagi Elabbasi

Re: Conjugate heat transfer Interface boundary condition


COMSOL imposes temperature continuity at the fluid-structure boundary in a conjugate heat transfer problem. There is no need for a different thermal boundary condition there. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection.

Nagi Elabbasi
Veryst Engineering


Dear Dr. Elabbasi,

I am doing a simulation on the heat ans mass transfer in some grains using both the conjugate heat transfer in solids (nitf) and transport of diluted species (chds). The simulation for the heat transfer is quiet good but the not in the mass transport. Maybe there are some issues on the type of mesh that I am using. Anyway, I'll just leave it at that for the moment.

What I would like to inquire right now is the problem on the heat loss due to evaporation. The passing of the heat air to the surface of the solid boundary caused heat and mass transfer at the same time resulting to some degree of heat loss. Does the nitf node of COMSOL account for this loss?

Because I want to consider the heat loss, I tried adding the convective cooling. However, I am having some problems because the boundaries of the grains are inactive (Attached picture). Am I doing it correctly? Is there any other way to do this so that the heat loss can be included in the analysis?

Thank you very much in advance.

Beat regards,
Jonathan Perez

Attachments:   Inquiry to Dr. Elabbasi.PNG  

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