Abstract: The grid-independent solution is a premise of numerically studying turbulent convective heat transfer, while the appropriate treatment of boundary conditions is critical to the accuracy of numerical results. In this paper, turbulent heat transfer in a squared U-bend is studied with the SST k-ω model. The flow and temperature fields are calculated, and the grid-independent solutions of velocity and temperature fields are analyzed emphatically. Under the second type of boundary condition (heat flux condition), the influence of two treatments on the accuracy of numerical solutions is contrastively analyzed. Because the coupling of velocity and temperature fields is weak, the mesh size required for grid-independent solutions is different for the two fields. A finer mesh is needed for the grid-independent solution of the temperature field. The comparative analysis of the two treatments of the heat flux condition demonstrates that the algebraic formulation of Kader (1981) is in good agreement with experimental data even though the mesh is relatively coarse, so it has better versatility and grid adaptability.