What Is the Realizable Two-Layer K-Epsilon Model?

Two-layer type

Select a two-layer formulation.

Shear Driven (Wolfstein)

Selects the two-layer formulation of Wolfstein [40]. This is appropriate for flows that are not dominated by buoyancy forces. See Eqns. (253) to (256).

Buoyancy Driven (Xu)

Selects the two-layer formulation of Xu et al. [41]. This is appropriate for flows that are dominated by buoyancy forces. See Eqns. (257) to (260).

Convection

Selects the convection scheme to be used.

1st-order

Selects the convection scheme to be used.

2nd-order

Selects the second-order upwind convection scheme.

Expert Properties

Aside from

, which is computed using Eqn. 212, the expert properties are identical to those of the standard K-Epsilon model. Note that the coefficients in the model have different values, as specified by Eqn. 214.

Unless you are thoroughly familiar with the theoretical aspects of this model and the discretization techniques used in STAR-CCM+, we recommend that you not make any changes within the Expert category. The values in that category reflect both the model's design and discretization approaches that have been optimized for accuracy and performance. Tampering with them may diminish the effectiveness of the model.

C2e

The coefficient , see Eqn. 239.

Cmu

The coefficient , see Eqn. 239.

Two-Layer Delta ReY

The value of used in Eqn. 249.

Buoyancy Production of Dissipation

Determines how the coefficient in Eqn. 188 is calculated.

None

Neglects the term .

Boundary Layer Orientation

Computes according to Eqn. 196.

Thermal Stratification

Computes according to Eqn. 195.

Normal Stress Term

Determines whether the full Boussinesq approximation used.

Ticked

The stress tensor is modeled as and production is computed using Eqn. 189.

Cleared

The stress tensor is modeled as and production is modeled using the simplified expression .

Two-Layer ReY*

The value of used in Eqn. 248.

Sarkar

The coefficient , see Eqn. 198.

Secondary Gradients

Neglect or include the boundary secondary gradients for diffusion and/or the interior secondary gradients at mesh faces.

Include both secondary gradients.

Off

Exclude both secondary gradients.

Interior Only

Include the interior secondary gradients only.

Boundaries Only

Include the boundary secondary gradients only.

Sigma_e

The coefficient , see Eqn. 239.

Sigma_k

The coefficient , see Eqn. 239.

Tdr Minimum

The minimum value that the transported variable is permitted to have. An appropriate value is a small number that is greater than the floating point minimum of the computer.

Tke Minimum

The minimum value that the transported variable is permitted to have. An appropriate value is a small number that is greater than the floating point minimum of the computer.