What Is the Standard Low-Reynolds Number K-Epsilon Model?

The low-Reynolds number model by Lien et al. [36] is dubbed the "Standard Low-Reynolds Number K-Epsilon Model" because it has identical coefficients to the Standard K-Epsilon model, but provides additional damping functions that allow it to be applied in the viscous-affected regions near walls. This model is recommended for natural convection problems, particularly if the Yap correction is invoked.

Properties

Constitutive Relation

Selects the type of constitutive relation to be used.

Linear

Selects the linear constitutive relation. This is recommended for most simulations. See Eqn. 239.

Quadratic

Selects the quadratic constitutive relation (see Eqn. 240) and activates two subnodes:

Non-Linear Cmu Coefficients

Non-Linear Quadratic Coefficients

Cubic

Selects the cubic constitutive relation (see Eqn. 241) and activates three subnodes:

Non-Linear Cmu Coefficients

Non-Linear Quadratic Coefficients

Non-Linear Cubic Coefficients

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.

Yap Correction

Defines whether or not to include the Yap correction of Eqn. 199 in the transport equation for .

Ticked

The Yap correction is included.

Cleared

The Yap correction is not included.

Expert Properties

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.

C1e

The coefficient , see Eqn. 239.

C2e

The coefficient , see Eqn. 239.

Cd0

The coefficient , see Eqn. 222.

Cd1

The coefficient , see Eqn. 222.

Cd2

The coefficient , see Eqn. 222.

Cmu

The coefficient , see Eqn. 239.

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 is used.

Ticked

The linear stress tensor is modeled with Eqn. 239, and the linear production is modeled using Eqn. 189.

Cleared

The linear stress tensor is modeled as , rather than the full expression of Eqn. 239. Furthermore, the linear stress used in the turbulent production is assumed to be rather than the full expression of Eqn. 189.

Realizable Scale Option

Enables realizability constraints on the time scale. See Eqn. 203.

Ticked

Enables realizability constraints.

Cleared

Disables realizability constraints.

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.

Yap Cl

The Yap correction for the coefficient

Yap Cw

The Yap correction for the coefficient