The Turbulent Flow, Spalart-Allmaras version of the Rotating Machinery, High Mach Number Flow (hmnf) interface (), found under the High Mach Number Flow > Rotating Machinery, High Mach Number Flow > Turbulent Flow branch (), is used to simulate

gas flows in geometries with one or more rotating parts and gas 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 is available for 3D and 2D components and it combines the High Mach Number Flow, Spalart-Allmaras interface (), with a Rotating Domain under Definitions > Moving Mesh.

There are two study types available for this physics interface. Using the Time Dependent study type, rotation is achieved through moving mesh functionality, also known as sliding mesh. Using the Frozen Rotor study type, the rotating parts are kept frozen in position, and rotation is accounted for by the inclusion of centrifugal and Coriolis forces. 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. A Wall Distance Initialization study type is automatically added. It also supports heat transfer in solids as well as surface-to-surface radiation. However, only fluid domains adjacent to pair boundaries are supported.

When this multiphysics interface is added, the following default nodes are also added in the Model Builder under High Mach Number Flow, Spalart-Allmaras — Fluid, Initial Values, Wall, and Thermal Insulation. When a pair boundary is created, the Continuity node is automatically added. 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. See Moving Mesh for more details of the Rotating Domain node added automatically in the Model Builder under Definitions > Moving Mesh.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is hmnf.

The Reference temperature Tref is used to define the reference enthalpy Href which is set to 0 J/kg at pref (1 atm) and Tref. When the Include kinetic energy checkbox is selected, the conservative total-energy equation is solved.

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 node.

Edit the model parameters of the Spalart–Allmaras model as needed. Turbulence model parameters are optimized to fit as many flow types as possible, but for some special cases, better performance can be obtained by tuning the model parameters. For a description of the turbulence model and the included model parameters see Theory for the Turbulent Flow Interfaces.

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, Reciprocal wall distance G (SI unit: 1/m) and Undamped turbulent kinematic viscosity nutilde (SI unit: m2/s) variables are also available.