Reynolds-averaged Navier–Stokes “RANS” turbulence models (such as k-ε models) are still widely used for engineering applications because of their relatively simplicity and robustness. In fully developed plane channel flow (i.e. the flow between two infinitely large plates), even if available models and near-wall treatments provide adequate mean flow velocities, they fail to predict suitable turbulent kinetic energy “TKE” profiles near walls. TKE is involved in determination of eddy viscosity/diffusivity and could therefore provide inaccurate concentrations and temperatures. In order to improve TKE a User Defined Function “UDF” based on an analytical profile for TKE was developed and implemented in FLUENT. Mean streamwise velocity and TKE profiles were compared to DNS data for friction Reynolds number Reτ = 150. Simulation results for TKE show accurate profiles. Simulation results for horizontal heated channel flows obtained with FLUENT are presented. Numerical results are validated by direct numerical simulation “DNS” data for Reτ = 150.