The Turbulent Flow, k-ω Interface
The Turbulent Flow, k-ω (spf) interface () is used for simulating single-phase flows at high Reynolds numbers. The physics interface is suitable for incompressible flows, weakly compressible flows, and compressible flows at low Mach numbers (typically less than 0.3).
The equations solved by the Turbulent Flow, k-ω interface are the Reynolds-averaged Navier-Stokes (RANS) equations for conservation of momentum and the continuity equation for conservation of mass. Turbulence effects are modeled using the Wilcox revised two-equation k-ω model with realizability constraints. The k-ω model is a so-called low-Reynolds number model, which means that it can resolve the flow all the way down to the wall.
The Turbulent Flow, k-ω interface can be used for stationary and time-dependent analyses. The main feature is Fluid Properties, which adds the RANS equations and the transport equations for the turbulent kinetic energy k and the specific dissipation ω, and provides an interface for defining the fluid material and its properties. When this physics interface is added, the following default nodes are also added in the Model Builder: Fluid Properties, Wall, and Initial Values.
Except where included below, see The Laminar Flow Interface and The Turbulent Flow, k-ε Interface for all the other settings.
Turbulence
A different turbulence model can be selected under Turbulence model. Laminar or creeping flow may be simulated by changing the Turbulence model type to None.
The Turbulence model property disables the Neglect inertial term (Stokes flow) check box, and for 2D components also the Shallow Channel Approximation check box.
Wall Treatment
The k-ω model employs per default an Automatic wall treatment, which switches between a low-Reynolds-number formulation and a wall function formulation depending on how well resolved the flow is close to the wall. The automatic wall treatment gives a robust formulation that makes the most out of the available resolution. The most robust, but least accurate option is select the Wall functions option.
Select the Low Re option in order to enforce resolution all the way down to the wall. This can be more accurate than the automatic wall treatment provided that the mesh is fine enough. Observe that the Low Re formulation requires the wall distance to be solved for prior to the flow.
Edit Turbulence Model Parameters
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 this physics interface the parameters are α, σk, σw, β0, β0, κv, and B.
Dependent Variables
The following dependent variables (fields) are defined for this physics interface:
Velocity field u and its components
Flow Through a Pipe Elbow: Application Library path CFD_Module/Verification_Examples/pipe_elbow