Large eddy simulation of a fully developed non-isothermal turbulent channel flow

Purpose– The purpose of this paper is to numerically study heated channel flow using direct numerical simulation (DNS) and large eddy simulation (LES) method. Using different domain size and different grid resolution it is show that filtering procedure is influenced and may results in very different solutions.Design/methodology/approach– Turbulent non-isothermal fully developed channel flow has been investigated using LES. The filtered Navier-stokes and energy equations were numerically solved with dynamic subgrid scale (SGS) model, standard Smagorinsky model or without additional model for the turbulent SGS stress and heat flux required to close the governing equations.Findings– The numerical LES results in comparison with the DNS data demonstrate that the LES computations may not always offers a reliable prediction of non-isothermal turbulent flow in open channel. It has been found that, even though the models reproduces accurately results for the flow field the thermal field computed using LES do not necessary match the DNS results. Introducing SGS model for scalar do not always show large improvement. One of the reason is thickness of hydrodynamic and thermal boundary layer. In the cases when boundary layers are very different it is not easy optimally set up control volumes in the domain.Originality/value– This is one of the first instance in which a results of numerical computations for different grid resolution, different stretching, SGS model is employed for non-isothermal turbulent channel flow. It shows that in the cases when boundary layers hydrodynamic and thermal are very different it is hardly find optimal grid resolution or stretching