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-   -   Under relaxation factors: Do they affect the end solution? (https://www.cfd-online.com/Forums/fluent/220124-under-relaxation-factors-do-they-affect-end-solution.html)

rsdevako August 25, 2019 15:09

Under relaxation factors: Do they affect the end solution?
 
Hello,


I am performing conjugate heat transfer CFD simulations for jet impingement.


Constant heat flux of 20,000 W/m^2 is provided at the base of the solid. The top of the solid is open to the fluid domain. The top of the solid domain has some protrusions.



  1. The heat flux measured on the top surface through the surface integral report was same as (area of bottom / area of top)*(heat flux at bottom). Is this how the value should be?
  2. When I change the under relaxation factor of energy to 0.8 (from 1), the heat flux value at surface is very low. Is there a specific way/calculation to implement the URFs?
What would be the source of error?



I would be able to provide more data if required.


Thanks.


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