# Standard k-epsilon model

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- | For k <br> | + | == Transport equations for standard k-epsilon model == |

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+ | For turbulent kinetic energy <math> k </math> <br> | ||

:<math> \frac{\partial}{\partial t} (\rho k) + \frac{\partial}{\partial x_i} (\rho k u_i) = \frac{\partial}{\partial x_j} \left[ \left(\mu + \frac{\mu_t}{\sigma_k} \right) \frac{\partial k}{\partial x_j}\right] + P_k + P_b - \rho \epsilon - Y_M + S_k </math> | :<math> \frac{\partial}{\partial t} (\rho k) + \frac{\partial}{\partial x_i} (\rho k u_i) = \frac{\partial}{\partial x_j} \left[ \left(\mu + \frac{\mu_t}{\sigma_k} \right) \frac{\partial k}{\partial x_j}\right] + P_k + P_b - \rho \epsilon - Y_M + S_k </math> | ||

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\mu_t = \rho C_{\mu} \frac{k^2}{\epsilon} | \mu_t = \rho C_{\mu} \frac{k^2}{\epsilon} | ||

</math> | </math> | ||

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== Production of k == | == Production of k == | ||

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</math> | </math> | ||

- | == Effect of | + | == Effect of buoyancy == |

:<math> | :<math> | ||

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</math> | </math> | ||

- | == Model | + | == Model constants == |

:<math> | :<math> | ||

C_{1 \epsilon} = 1.44, \;\; C_{2 \epsilon} = 1.92, \;\; C_{\mu} = 0.09, \;\; \sigma_k = 1.0, \;\; \sigma_{\epsilon} = 1.3 | C_{1 \epsilon} = 1.44, \;\; C_{2 \epsilon} = 1.92, \;\; C_{\mu} = 0.09, \;\; \sigma_k = 1.0, \;\; \sigma_{\epsilon} = 1.3 | ||

</math> | </math> | ||

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+ | [[Category:Turbulence models]] |

## Revision as of 15:16, 21 June 2007

## Contents |

## Transport equations for standard k-epsilon model

For turbulent kinetic energy

For dissipation

## Modeling turbulent viscosity

Turbulent viscosity is modelled as:

## Production of k

Where is the modulus of the mean rate-of-strain tensor, defined as :

## Effect of buoyancy

where Pr_{t} is the turbulent Prandtl number for energy and g_{i} is the component of the gravitational vector in the ith direction. For the standard and realizable - models, the default value of Pr_{t} is 0.85.

The coefficient of thermal expansion, , is defined as