The Basis of an Industry-standard Aerodynamic Computation and its Theoretical Basis with Inferences and Applications

Abstract

“The PNS method is in very widespread use; indeed, it forms the basis of an industry-standard computer program, which is used by virtually all major aerodynamics laboratories and companies.”(John D. Anderson Jr. American aerodynamicist 2006). Several PNS Eqs. With different slightly viscous terms and different name were suggested between the late 1960s and the late 1970s, in which the simplified NS Eqs. suggested by Z.Gao in 1967 was called by F.G.Zhuang(Academician, China) etal as first PNS. In early studies of PNS, it is not very clear what kind of basic flow is described by PNS Eqs., there is no basic fluid theory corresponding to PNS. The author presented a PNS's fluid basic theory: viscous/inviscid interacting shear flow (ISF) theory (including laminar, perturbed and turbulent flow theories). ISF consists of viscous shear layer and neighboring outer inviscid flow. Main points of ISF theory and inferences are as follows. Both the flow law and mathematical definition of ISF's viscous layer and ISF's governing Eqs. written in ISF's optimal coordinates, that is a fitted dividing flow surface orthogonal coordinates, are presented. The evolution laws of physical scales of ISF's viscous layer flow are solved, which do generate small scale structure and then do cause local sudden increase of several physical quantities(such as heat flux etc.). The PNS Eqs. can be simplified further on the dividing flow surface and the resultant Eqs. are called dividing flow surface criteria, whose two special cases are wall-surface criteria (WSC)for solutions of NS- and Euler Eqs. NS numerical solutions ought to satisfy WSC, which are proved numerically by some computations. People can obtain NS grid independent solution by operation of NS numerical solutions satisfying progressively the WSC. Especially, this criteria can evaluate the departure of NS numerical solutions from NS true solution by just one time NS calculation on one set of grid and are theoretical methods evaluating creditability of NS numerical solutions, and based on that some people suggest that the WSC method may be used as an ingenious substitute for the grid convergence analysis method in common use and that the WSC method and ISF theory are called Gao's criteria method and Gao's ISF theory, respectively. Some applications of ISF theory and its inferences to CFD are fruitful and creativeness and then research on this aspect is worth deepening and widening.