Comparative study on the numerical computation of convective heat transfer over rough surfaces

To compute the convective heat transfer coefficient in the ice shape simulation process, three different methods that take wall roughness into account were presented, namely, the traditional integral boundary layer (IBL) method, a method based on k-ε turbulence model plus standard wall function (k-ε method) and a method based on extension of the Spalart-Allmaras turbulence model (S-A method). The convective heat transfer coefficients were calculated for a 15 cm diameter cylinder with an equivalent sand grain roughness height of 1.35 mm under Reynolds numbers of 8.8×10⁵, 2.8×10⁵ and 4. 8×10⁴ respectively. Comparisons show that IBL and S-A method have the same trends. Near the stagnation point, the predicted results show laminar features, and coincide with experimental data. Both methods overpredict the heat transfer in the following turbulent region, but S-A method agrees better with the experiment. The k-ε method overpredicts the heat transfer near stagnation region.