2011 Volume 19 Issue 3 Pages 59-70
In this study, the essential spatial resolution for Direct numerical simulation (DNS) of passive scalar transport in a channel flow was investigated at friction Reynolds number Reτ = 150 and Prandtl number Pr = 5 by using the high accuracy DNS data, which resolved full scales of second-order temperature derivative. In spite of lack the spatial resolution less than dynamical velocity fluctuations, the coarser DNS results were finely agreed with the high accuracy DNS results, as far as Nusselt number to temperature turbulent energy dissipation. This is why the larger scale in the temperature inertial range plays the role of the real dissipative smaller scale. Results of finer numerical grids for temperature field than velocity field, follow the temperature spectrum profile in the range of the fine smallest scale. It indicates that dynamical process in the velocity dissipative range might not impact on the statistic behavior of the smallest temperature scale.
