Research And Application Of Blending The Eddy-viscosity And Reynolds-stress Models With High-order Scheme

With the increasing complexity of aircraft shape design,the requirements for CFD are higher and higher.Especially in the face of the sudden changes of the average strain rate,curved surface,a second movement of the pipe,etc,the eddy-viscosity model in the case of engineering RANS methods already can not meet the requirements.Although it has the advantages of high efficiency,only considering first-order turbulence statistics,many complex flow field structure cannot be captured.We should consider the second order or higher order turbulence statistics.The second-ordermoment turbulence closure under the RANS framework is also called Reynolds-stress model(RSM),but its development is limited by its low efficiency and poor robustness.Hence a blending eddy-viscosity and Reynolds-stress model is developed in this paper.Considering the high efficiency and robustness of eddy-viscosity model and the advantages of Reynolds-stress model in capturing fine flow field,the research and application are carried out with high-order scheme WCNS.In this paper,the structure of the hybrid model is first derived,and the eddyviscosity equation is used as the length scale coupling Reynolds-stress transport equation.Then,standard examples including zero pressure gradient flat plate,wallmounted hump separated flow,and wing-body assembly are selected to evaluate the efficiency.The results show that the newly constructed model has the advantage of high computational efficiency,and the accuracy of the model is generally better than that of the eddy-viscosity model such as SA model.On the basis of this model,through the zero pressure gradient flat plate case,coefficient of calibration are carried out to explore without wall distance version.A series of standard cases such as airfoil near-wake and wing-body combination are selected for confirmation.The results show that wall-distance-free model are better than the original version and efficiency is improved.Finally,the adaptive scale constraint is introduced to study unsteady flow.Compared with SAS model,which are with adaptive scale constraint,the results of the new model are better than SAS,indicating that the model has the advantage of simulating unsteady flow problems.