kLowReWallFunction
boundary condition provides a wall constraint on the turbulent kinetic energy, i.e. k
, for low- and high-Reynolds number turbulence models.kLowReWallFunction
condition inherits the traits of the fixedValue boundary condition.Required fields:
k | Turbulent kinetic energy [m2/s2]
The model expressions for k
for viscous and inertial sublayers are switched in a stepwise manner:
\[ k = \max(k_{log} u_\tau^2, \zeta) \qquad if \quad y^+ > y^+_{lam} \]
\[ k = \max(k_{vis} u_\tau^2, \zeta) \qquad if \quad y^+ <= y^+_{lam} \]
with
\[ k_{log} = \frac{\ln (y^+) C_k}{\kappa} + B_k \]
\[ k = \frac{2400 C_f}{C_{eps2}^2} \]
\[ y^+ = \frac{u_\tau y}{\nu_w} \]
\[ u_\tau = C_\mu^{1/4} \sqrt{k} \]
\[ C_f = \frac{1}{(y^+ + C)^2} + \frac{2 y^+}{C^3} - \frac{1}{C^2} \]
where
\( k \) | = | Turbulent kinetic energy [m2/s2] |
\( k_{vis} \) | = | k prediction in the viscous sublayer |
\( k_{log} \) | = | k prediction in the inertial sublayer |
\( y \) | = | Wall-normal height [m] |
\( y^+ \) | = | Estimated wall-normal height of the cell centre in wall units |
\( y^+_{lam} \) | = | Estimated intersection of the viscous and inertial sublayers in wall units |
\( u_\tau \) | = | Friction velocity [m/s] |
\( \zeta \) | = | Small value to prevent floating point exceptions |
\( C_\mu \) | = | Empirical model constant [-] |
\( \nu_w \) | = | Kinematic viscosity of fluid near wall [m2/s] |
Example of the boundary condition specification:
<patchName> { // Mandatory entries (unmodifiable) type kLowReWallFunction; // Optional entries (unmodifiable) Ceps2 1.9; Ck -0.416; Bk 8.366; C 11.0; // Optional (inherited) entries ... }
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: kLowReWallFunction | word | yes | - |
Ceps2 | Model coefficient | scalar | no | 1.9 |
Ck | Model coefficient | scalar | no | -0.416 |
Bk | Model coefficient | scalar | no | 8.366 |
C | Model coefficient | scalar | no | 11.0 |
The inherited entries are elaborated in:
fixedValueFvPatchField
nutWallFunctionFvPatchScalarField
Cmu
, kappa
, and E
are obtained from the specified nutWallFunction
in order to ensure that each patch possesses the same set of values for these coefficients.Source code