The High Mach Number Flow, Spalart–Allmaras Interface
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.
The physics interface solves for conservation of energy, mass, and momentum. Turbulence effects are modeled using the one-equation Spalart–Allmaras turbulence model. The Spalart–Allmaras model is a so-called low-Reynolds number model, which means that it resolves the velocity, pressure, and temperature fields all the way down to the wall. The Spalart–Allmaras model depends on the distance to the closest wall. The physics interface therefore includes a wall distance equation. It also supports heat transfer in solids as well as surface-to-surface radiation.
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.
Turbulence
The default Turbulence model type is RANS-EVM, the default Turbulence model is Spalart–Allmaras. The Heat transport turbulence model is implicitly set to Turbulent Prandtl number. The default Turbulent Prandtl number model is Kays–Crawford, which can be changed to Extended Kays–Crawford or User-defined turbulent Prandtl number. For Extended Kays–Crawford, enter a Reynolds number at infinity Re∞. For User-defined turbulent Prandtl number, enter a Turbulent Prandtl number PrT.
The values or expressions required are entered in the Model Inputs section of the Fluid feature node. For the description of theory of turbulent heat transport see Turbulent Conductivity.
Dependent Variables
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.
•
The Heat Transfer Module Interfaces in the Heat Transfer Module User’s Guide
•
Domain, Boundary, Edge, Point, and Pair Nodes for the High Mach Number Flow Laminar and Turbulent Interfaces
•
The High Mach Number Flow, Laminar Interface
Transonic Flow in a Sajben Diffuser: Application Library path CFD_Module/High_Mach_Number_Flow/sajben_diffuser