The convection coefficient uses “Wall Func. Heat Tran. Coeff” (from Fluent) or “Wall Heat Transfer Coefficient” (from CFD-Post). This is based on wall functions and the reference temperature used for this formulation is “Wall Adjacent Temperature” (CFD near-wall temperature). When using Fluent, the convection coefficient will always be based on the wall function heat transfer coefficient so the ambient temp type should always be kept as “CFD near-wall Temperature”. This option is here because CFX users have the option to define the HTC based on a constant value, in which case, the “Ambient Temp Type” should be set to constant to match.