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Unrealistic Temperature Gradients

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Old   December 15, 2014, 08:20
Default Unrealistic Temperature Gradients
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Hello,

I want to keep it short and describe my problem.

I generated a 2D Mesh for ribbed channel where I want to analyse conjugate Heat Transfer and validate the Nusselt results with some experimental data.

I set a constant heat flux for the channel and rib bottom (conduction threw the solid is calculated). Air flows through the channel.

I've generated a grid which had a really good accurancy but I couldn't get satisfactory results for the validation. Based on that I decided to refine the mesh near the walls and in the solid. I refined the mesh just in the area which is essential for my analysis. This means the mesh was changed just in two ribs which are placed in the back part of the channel.

I expected to get better results for Nu coefficients of the refined mesh. However I got unrealistic temperature gradients in the refined region.
Temperature gradients in the other region remained the same as the results before refinement.

I put some pictures in the attachment for better demonstration of my problem.

I hope this helps.Thank you.
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Old   December 15, 2014, 08:27
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I used the k-omega SST model of solving turbulence. Mentionable is also that I didn't achieve a satisfactory accuracy for the refined mesh simulation.
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Old   December 16, 2014, 08:46
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no ideas?
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