The Turbulent Flow, Low Re k-ε version of the Rotating Machinery, Nonisothermal Flow interface (), found under the Fluid Flow > Nonisothermal Flow > Rotating Machinery, Nonisothermal Flow branch () when adding a physics interface, is used to simulate turbulent flow and heat transfer in equipment containing one or more rotating parts.

This physics interface combines the capabilities of the Rotating Machinery, Turbulent Flow, Low Re k-ε interface and the Heat Transfer in Fluids interface, and can be used to simulate high Reynolds number fluid flows where the fluid properties depend on the temperature. Furthermore it is also possible to include heat transfer in solids, stationary and rotating, as well as surface-to-surface radiation and radiation in participating media. The physics interface is available in 2D and 3D and supports low Mach number (typically less than 0.3) flows, as well as non-Newtonian fluids.

The physics interface solves for conservation of energy, mass, and momentum in fluids and for conservation of energy in solids. Turbulence effects are modeled using the AKN two-equation k-ε model with realizability constraints. The AKN model is a so-called low-Reynolds number model, which means that it can resolve the flow and heat transfer all the way down to the wall. The AKN model depends on the distance to the closest wall. The physics interface therefore includes a wall distance equation.

Four study types available for this physics interface. Using the Transient with Initialization study type, the rotation is achieved through moving mesh functionality, also known as sliding mesh. Using the Frozen Rotor with Initialization study type, the rotating parts are kept frozen in position, and the rotation is accounted for by the inclusion of centrifugal and Coriolis forces. The Time Dependent, One-Way NITF and Frozen Rotor, One-Way NITF study are used for frozen rotor and time-dependent nonisothermal flow computations where the temperature variations are so small that they do not affect the flow. All study types include an initial Wall Distance Initialization step in order to compute the wall distance. See Theory for the Rotating Machinery Interfaces in the CFD Module User’s Guide.

When adding the multiphysics interface, the Turbulent Flow, low Re k-ε and Heat Transfer in Fluids interfaces are added to the Model Builder. A Moving Mesh interface with a Rotating Domain node is added automatically in the Model Builder under the Definitions node. In addition, the Multiphysics node is added, which automatically includes the multiphysics coupling feature Nonisothermal Flow. The following default nodes are also added in the Model Builder under Turbulent Flow, low Re k-ε — Fluid Properties, Wall, and Initial Values; and under Heat Transfer in Fluids — Fluid, Thermal Insulation, and Initial Values.

See Rotating Machinery, Nonisothermal Flow, Laminar Flow Interface for details.