Turbulence modeling for computational aerodynamics

Modeling of Turbulent Separated Flows for Aerodynamic Applications

“…The mod i fie d zero-equa tion model predicts skin-friction values that are much to o low downst ream of the weak interaction, and this manifests itself more c r i tically in the strong-interaction case by predicting reattachment too fa r downs t ream and velocity pro f iles that do not compare well with expe riment. On the other hand, velocity profiles and shape factors in the downstream region are predicted better by the two-equation model, even for the s t rongi nte r action case in which skin friction is somewhat overpred i cted (see Marvin 1982). It is thought that the f a ilure of the t wo -e quation mode l to predict the ski n fricti on resides in the low-Reynolds-number modeling terms developed to allow i ntegration to the wall, but t his must be investi gated further and in light of the experimental ob servations on unsteadiness, which is discussed nex t.…”

“…In addition to the traditional role of providing basic understanding of the controlling mechanisms, they must also provide guidance for modeling approximations and provide sufficient detail so that accurate checks on computational output can be made. A synergistic framework for advancing computational a e rodynamics consisting of closely coordinated experiments and computations was described by Marvin (1982). The continued necessity for data required to support -, the development of research-, pilot-, and production-type computer codes was emphasized in that work and will not be repeated here.…”

“…Nevertheless, a series of building-block or bench-mark flows has been developed that can assist in the development of computational methods (e.g., see Marvin 1982). Those used for the problems discussed in this paper are given in tables 1-6.…”

“…A disadvantage is the long computing time and large storage limitations of current computers, which has hampered attempts to focus directly on turbulence modeling without considering numerical resolution and accuracy. As it now stands, the competing elements of turbulence modeling, numerical resolution, and accuracy must all be considered in any evaluation of our ability to compute flows with separation (Marvin 1982). …”

“…A general description of various turbulence-modeling a pproaches used for applications in aerodyna.mic flows was presented by Marvin (1982). where p is the hydrostatic pressure; 2/3 pk is the pressure asso- (3) ciated with the turbulence; ~ is the thermal conductivity, including the turbulent diffusivity; and PE is the turbulent eddy viscosity.…”