Increasing of total temperature
 

Hello,

I have a general 3D flow field. It contains a large region (a tube) where strong swirling zone occurs. In this zones the total temperature always becomes larger than the inlet total temperature which was defined as boundary condition. The walls are adiabatic and free slip. I don’t understand this. How can the total temperature increase above the inlet total temperature if there is not heat input and friction at the walls. Is this because of the viscosity (internal friction) of material?

Regards
Roland

Have you got viscous dissipation turned on? Yes, this could be one explanation.

Also if the simulation is not fully converged you could get this. Also inadequate mesh resolution could contribute.

Is the total temperature locally above the inlet value or is it the massFlowAve(Total Temperature) on a slice plane through the tube? If it's just locally then that's allowed to happen physically. It's similar to a local rise in Total Pressure (see "Rise of Total Pressure in Frictional Flow" - http://adsabs.harvard.edu/abs/1995AIAAJ..33..772I)

What do you mean by inadequate mesh? and how it causes the temperature increase more than total

Overshoots have been there since man invented numerical methods. These overshoots can be persistent when your mesh has low quality.