The High Mach Number Flow, Spalart–Allmaras (hmnf) interface (), found under the High Mach Number Flow>Turbulent Flow branch () when adding a physics interface, is used to model gas flows at high Reynolds number where the velocity magnitude is comparable to the speed of sound, that is, turbulent flows in the transonic and supersonic range.

This is a predefined multiphysics interface which combines a turbulence Spalart–Allmaras model for compressible flow with a heat transfer model. As shown in Table 5-1, the turbulent versions of the physics interfaces differ by where they are selected when adding a physics interface and the default Turbulence model selected — Spalart–Allmaras for this physics interface.

When this physics interface is added, the following default nodes are also added in the Model Builder — Fluid, Wall, Thermal Insulation, and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions, volume forces, and heat sources. You can also right-click the node to select physics features from the context menu.

The default Turbulence model type is RANS, the default Turbulence model is Spalart–Allmaras, and the default Heat transport turbulence model is Kays–Crawford. Alternatively, select User-defined turbulent Prandtl number. The turbulent Prandtl number model describes the influence of the turbulent fluctuations on the temperature field. It is always possible to have a user-defined model for the turbulence Prandtl number. Enter the user-defined value or expression for the turbulence Prandtl number in the Model Inputs section of the Fluid feature node.

The dependent variables (field variables) are the Velocity field u (SI unit: m/s), the Pressure p (SI unit: Pa), and the Temperature T (SI unit: K). For turbulence modeling and heat radiation, the Reciprocal wall distance G (SI unit: 1/m) and Undamped turbulent kinematic viscosity nutilde (SI unit: m2/s) variables are also available.