## Simulation CFD

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# Heat generated in Thermal CFD

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I am doing Natural Convection thermal analysis using CFD-2013.

One of the component in the analysis is given a boundary condition of ‘Total heat generation’ as Temperature Dependent and Piecewise Linear.

After the solution has converged, I am able to see the ‘Volume Averaged Temperature’ of that component from: results - review - component thermal summary file.

My question is- how to check the corresponding Heat Generated by that component at __that particular Average temperature__?

# Re: Heat generated in Thermal CFD

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As I understand this is a Heat Transfer problem.

You have assigned temperature dependent heat input to a source. Your analysis has successfully completed. And you can aslo read the component temperature in Component Thermal Summary.

Now your question is -

What heat input CFD has used corresponding to the temperature you read in results? Is that right?

# Re: Heat generated in Thermal CFD

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I assume you specified the heat source as a piecewise linear fuction of temperature, can you put snaps of the function definition and its plot?

OJ

# Re: Heat generated in Thermal CFD

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Yes Abhijit !! That is what I want to know.

# Re: Heat generated in Thermal CFD

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Omkar, attached is the snapshot that you needed.

We can definitely see the heat generated from the piecewise linear plot. The thing is, we can read the Heat Generated at a particular temp. But when I give this heat input with " Total Heat generation: disabled " , the solution gives a different higher temp value.

for e.g.

When i give boundary cond. - "Total heat generation- Enabled, and piecewise liner", i get the avg component temp as 200 degC. Corresponding to this temp i read the heat generated as 6.5W from the plot.

Now when i solve again by giving 6.5W input but with "Total Heat Generation- Disabled" the result i get is 212 degC which is much higher.

What would be the reason for this temp variation??

# Re: Heat generated in Thermal CFD

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The plots weren't attached in the post!

OJ

# Re: Heat generated in Thermal CFD

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Omkar, attached is the snapshot that you needed.

We can read the Heat Generated at a particular temp from the piecewise linear plot. But when I give this heat input with "Temperature dependent: disabled ", the solution gives a different higher temp value.

For e.g.

When I give boundary cond. of Total heat generation with “Temperature dependent: Enabled”, and 'piecewise liner', i get the avg component temp as 200 degC. Corresponding to this temp i read the heat generated as 6.5W from the plot.

Now when i solve again seperately by giving 6.5W input but with " Temperature dependent: Disabled" the result i get is 212 degC which is much higher.

What would be the reason for this temp variation??

# Re: Heat generated in Thermal CFD

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Looking at your image I see two things that you might want to check:

This is perhaps a natural convection model?

Have you checked to see from the Summary file (or manual hand calculation) the amount of heat picked up by the fluid (m_dot*Cp*dT) ?

Is the block assigned the Heat Gen vs Temp isothermal? As you have it assigned we are using the part centroid for our measurement as to where we will determine the temperature that drives the Heat Generation, you may want to probe in a similar fashion for consistency.

Apolo