Initial Values for Generate New Turbulence Model Interfaces
A major advantage with the Generate New Turbulence Model Interface feature is that it can express initial values for the new turbulence model in terms of the original model. This makes it possible to first solve a problem using a simple, but robust, turbulence model, such as the k-ε model, and then switch to a more advanced model.
Unless the Initial value from study is None, the Generate New Turbulence Model Interface initial values for velocity and pressure are taken directly from the solution of the parent model. The initial values of turbulent dependent variables are estimated using the solution from the selected study:
•
When the parent model is a Laminar Flow model, or when Initial value from study is None, turbulent dependent variables get their default initial values.
•
Initial values of dependent variables that exist in both the parent model and the generated model are taken directly from the selected study.
•
When the parent model is of RANS-RSM type and the generated model has Dependent Variable k, its initial value is
It is also implied that this value of k is used when a RANS-EVM is generated from a RANS-RSM
•
When a RANS-RSM is generated from a RANS-EVM
where Kij is the K_stress_tensor variable, while k is the Dependent Variable of the parent model if it exists or kinit otherwise
•
When the parent model is ε-based and the generated model is ω-based, the initial value of ω is
•
When the parent model is ω-based, and the generated model is ε-based (for v2-f Cμ is replaced by (2/3)Cμ −v2f, and for Elliptic Blending R-ε it is replaced by 0.09), the initial value of ε is
•
When the parent model is Algebraic yPlus, and the generated model is ε-based (for v2-f Cμ is replaced by (2/3)Cμ −v2f, and for Elliptic Blending R-ε it is replaced by 0.09), the initial values of k and ε are:
where LT = max(κay, (y∗υ)/uτ) and uτ = |u|/u+.
•
When the parent model is Algebraic yPlus and the generated model is ω-based, the initial values of k and ω are
•
When the parent model is L-VEL, and the generated model is ε-based (for v2-f Cμ is replaced by (2/3)Cμ −v2f, and for Elliptic Blending R-ε it is replaced by 0.09), the initial values of k and ε are
where LT = max(κly, (κlυEl)/uτ).
•
When the parent model is L-VEL, and the generated model is ω-based, the initial values of k and ω are
•
When the parent model is Spalart–Allmaras and the generated model is ε-based (for v2-f Cμ is replaced by (2/3)Cμ −v2f, and for Elliptic Blending R-ε it is replaced by 0.09), the initial value of k and ε are:
•
When the parent model is Spalart–Allmaras and the generated model is ω-based, the initial values of k and ω are
•
When the generated model is Spalart–Allmaras turbulent mode, and the parent model any turbulence model but Spalart–Allmaras, the initial value of the dependent variable is νinit = μT/ρ.