Rahman-Siikonen-Agarwal Model
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== Introduction == | == Introduction == | ||
- | The Rahman | + | The Rahman-Agarwal-Siikonen (RAS) Turbulence model is a one-equation eddy viscosity model based on <math>k-\epsilon</math> closure. The R-transport equation along with the Bradshaw and other empirical relations are used to solve for the turbulent viscosity. A damping function, <math>f_\mu</math>, is used to represent the kinematic blocking by the wall. To avoid defining a wall distance, a Helmholtz-type elliptic relaxation equation is used for <math>f_\mu</math>. The model has been validated against a few well-documented flow cases, yielding predictions in good agreement with DNS and experimental data. |
== RAS Model == | == RAS Model == |
Latest revision as of 19:47, 8 July 2013
Introduction
The Rahman-Agarwal-Siikonen (RAS) Turbulence model is a one-equation eddy viscosity model based on closure. The R-transport equation along with the Bradshaw and other empirical relations are used to solve for the turbulent viscosity. A damping function, , is used to represent the kinematic blocking by the wall. To avoid defining a wall distance, a Helmholtz-type elliptic relaxation equation is used for . The model has been validated against a few well-documented flow cases, yielding predictions in good agreement with DNS and experimental data.
RAS Model
The turbulent eddy viscosity is given by
The R-transport Equation:
Realizable Time Scale:
Coefficient :
Damping Function:
Other Model Coefficients:
and :
Constants:
References
- Rahman, M. M., Siikonen, T., and Agarwal, R. K. (2011), "Improved Low Re-Number One-Equation Turbulence Model", AIAA Vol. 49, No.4, April 2011.