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-   -   Enhanced Wall Treatment - Thermal Effects (http://www.cfd-online.com/Forums/fluent/38271-enhanced-wall-treatment-thermal-effects.html)

Brian Tang October 17, 2005 09:00

Enhanced Wall Treatment - Thermal Effects
 
Hi, I'm using Fluent 6.1 with EWT, but I'm not entirely sure what the two options (thermal effects and pressure gradients) do. From the manual, it seems that it sensitises the enhanced wall function to heat transfer effects and pressure gradients, but I'm slightly confused: Does this mean that I only need to turn on thermal effects if I expect large heat transfer to/from the boundary layer, or will I need this option to get accurate heat transfer predictions?

Thanks, Brian

balaji_hrrn November 6, 2015 00:59

Enhanced Wall Treatment
 
http://www.afs.enea.it/project/neptu...#trb-du_dy-mod

This link will explain what this mathematically means. Beta and Gamma functions are the near wall thermal functions based on log-wall treatment, while alpha is for the pressure effects.

Notice that the alpha is inversely proportional to cube of velocity, which implies that for simulations having high velocity gradients in the Boundary Layer and with Ideal Gas materials, these terms become important to be modeled.

For eg. a hot gas flow from a combustor outlet must have both of these turned on, while for a case where pressure effects are predominant compared to thermal effects due to low residence times, pressure gradient effects should be enabled.


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