The Rotating Machinery, Laminar Flow (spf) interface (), found under the Single-Phase Flow > Rotating Machinery branch (), is used to simulate flow at low to moderate Reynolds numbers in geometries with one or more rotating parts. The physics interface supports incompressible, weakly compressible and compressible flows at low Mach numbers (typically less than 0.3). It also supports modeling of non-Newtonian fluids. The physics interface is available for 3D and 2D components.

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. In both types, the momentum balance is governed by the Navier–Stokes equations, and the mass conservation is governed by the continuity equation. See Theory for the Rotating Machinery Interfaces in the CFD Module User’s Guide.

When this physics interface is added, the following default physics nodes are also added in the Model Builder under Laminar Flow — Fluid Properties, Wall, and Initial Values. A Moving Mesh interface with a Rotating Domain node is added automatically in the Model Builder under the Definitions node. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions and volume forces. You can also right-click Laminar Flow to select physics features from the context menu. See Domain, Boundary, Pair, and Point Nodes for Single-Phase Flow in the CFD Module User’s Guide.

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 spf.

In addition to the settings described below, see The Creeping Flow, Laminar Flow, Turbulent Flow, Large Eddy Simulation, and Detached Eddy Simulation Interfaces in the CFD Module User’s Guide for all the other settings available. See Domain, Boundary, Point, and Pair Nodes for the Rotating Machinery Interfaces for links to all the physics nodes.

To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog. Normally these settings do not need to be changed.

Select the Use pseudo time stepping for stationary equation form checkbox to add pseudo time derivatives to the equation when the Frozen Rotor equation form is used. (Frozen rotor is a pseudo stationary formulation.) When selected, also choose a CFL number expression — Automatic (the default) or Manual. Automatic sets the local CFL number (from the Courant–Friedrichs–Lewy condition) to the built-in variable CFLCMP which in turn triggers a PID regulator for the CFL number. For Manual enter a Local CFL number CFLloc (dimensionless).