Interacting shear flow stability theory with application to improving computational method of simulating numerically high Reynolds number flows

On the basis of the interacting shear flow (ISF) theory proposed by the author, the ISF stability theory and its two inferences with application to improving computational methods of simulating numerically high Reynolds (Re) number inner/outer flows are presented in this paper. (1) In the RANS computations and an industry-standard PNS computations for high Reynolds number flows over bodies, predicting transition is always based on the classical boundary-layer theory coupled with experimental data; however, transition does not always occur originally in boundary-layer, initial transition may occur in dents, or small step or small cracks at wall, these local strong interaction flow regions may locate in boundary layer, but boundary-layer theory is not suitable for these flow regions, and transition occurs in strong interaction flow region near separation point etc. (2) Flow transition occurs always in interacting shear flow, ISF theory extracted by the author is composed of viscous shear layer and its neighbor outer inviscid flow with interaction each other; ISF summarizes many viscous-inviscid flows with basis meanings and engineering values, two typical example of ISF are the classical viscous boundary layer added its neighbor outer inviscid flow, and the viscous/inviscid flow near wall in high Re number inner/outer flows over bodies. (3) The interacting shear perturbed flow (ISPF) equations offer new theoretical computational method to simulate non-turbulence perturbed motion and transition in ISF. The ISF- equations and ISPF equations are respectively the same kind of PNS- and PSE- equations. Many works of using PSE analyses and computes boundary-layer stability show that it is perfectly feasible to compute perturbed flow of ISF and predict transition using ISPF (or PSE) equations. (4) The computational results given by solving simultaneously ISF- and ISPF equations are reasonable approximation of the direct numerical simulation (DNS) of ISF before transition. (5) Integrating the ISF stability theory and its two inferences with both of the traditional PNS method and the current RANS, RANS/LES methods (call them RANS method unitedly here) leads to several substantial improvements of this two methods. Such as, avoiding artificial assumption of transition location or estimating experientially transition location on the basis of the boundary layer stability theory etc.. Both of improved PNS- and RANS-methods compute simultaneously ISF- and ISPF-equations, that provide reasonable approximation of direct numerical simulation (DNS) of ISF before transition; after transition the improved PNS method computes parabolized RANS(PRANS) equations and the improved RANS method computes RANS, RANS/LES equations and both of this two calculations provide reasonable approximation of statistical average flow given by DNS of interacting shear turbulent flow. (6) In the improved these two methods, equation system is perfect and self-affirming, therefore they are ideal methods for computing high Re number inner/outer flows over bodies and would have broad prospects of development and application.