diff --git a/_docs_v7/Physical-Definition.md b/_docs_v7/Physical-Definition.md index c5b36555..71830f70 100644 --- a/_docs_v7/Physical-Definition.md +++ b/_docs_v7/Physical-Definition.md @@ -18,12 +18,15 @@ SU2 offers different ways of setting and computing this definition. This documen - [Flow Condition (Incompressible)](#flow-condition-incompressible) - [Thermodynamic and Gauge Pressure](#thermodynamic-and-gauge-pressure) - [Initial State and Non-Dimensionalization](#initial-state-and-non-dimensionalization) +- [Turbulence Models](#turbulence-models) + - [Spalart-Allmaras (SA)](#spalart-allmaras-model) + - [Shear Stress Transport (SST)](#shear-stress-transport) --- ## Reference Values ## -| Solver | Version | +| Solver | Version | | --- | --- | | `EULER`, `NAVIER_STOKES`, `RANS`, `INC_EULER`, `INC_NAVIER_STOKES`, `INC_RANS`, `FEM_EULER`, `FEM_NAVIER_STOKES` | 7.0.0 | @@ -47,7 +50,7 @@ The following table depicts the reference values used by most of the solvers in ## Free-Stream Definition (Compressible) ## -| Solver | Version | +| Solver | Version | | --- | --- | | `EULER`, `NAVIER_STOKES`, `RANS`,`FEM_EULER`, `FEM_NAVIER_STOKES` | 7.0.0 | @@ -79,7 +82,7 @@ For all schemes, as reference values for the density and temperature the free-st ## Flow Condition (Incompressible) ## -| Solver | Version | +| Solver | Version | | --- | --- | | `INC_EULER`, `INC_NAVIER_STOKES`, `INC_RANS` | 7.0.0 | @@ -97,3 +100,61 @@ The reference values $$\rho_{ref}, T_{ref}, v_{ref}$$ equal the initial state va **Note:** The initial state is also used as boundary conditions for `MARKER_FAR`. +## Turbulence Models ## + +| Solver | Version | +| --- | --- | +| `*_RANS` | 7.4.0 | + +This section describes how to setup turbulence models for RANS simulations. Turbulence is activated using the option `KIND_SOLVER= RANS`, or `KIND_SOLVER= INC_RANS` +A turbulence model can then be selected via the option `KIND_TURB_MODEL` +Different submodels and parameters are specified via the different options listed below. +The turbulent Prandtl number can be modified with the option `PRANDTL_TURB` (the default is 0.9). + +### Spalart-Allmaras (SA) ### + +SU2 implements several versions and corrections of the SA model. +The model is selected using `KIND_TURB_MODEL= SA` and the modifications via the `SA_OPTIONS` list. If this list is empty, then SU2 defaults to `SA-noft2`. +The freestream and inlet conditions are specified via the option `FREESTREAM_NU_FACTOR= 3` (ratio of SA variable to freestream kinematic viscosity). + +The following modifications are allowed (refer to [NASA's TMR](https://turbmodels.larc.nasa.gov/spalart.html) for further info): +- Versions: + - `NEGATIVE` - Negative SA model. + - `EDWARDS` - Edwards modification. + - `BCM` - BCM transitional model. + - `WITHFT2` - SA model **with** ft2 term, note that by default we omit this term. +- Corrections: + - `QCR2000` - Quadratic contitutive relation used in the stress tensor. + - `COMPRESSIBILITY` - Mixing layer compressibility correction. + - `ROTATION` - Dacles-Mariani et al. rotation correction. + +All the modifications can be combined with each other expect `NEGATIVE` and `EDWARDS`. +For example, to specify `SA-neg-R-comp-QCR2000` use `SA_OPTIONS= NEGATIVE, WITHFT2, ROTATION, COMPRESSIBILITY, QCR2000`. +**However, some combinations are not considered standard**, e.g. `SA-neg` should have the ft2 term, whereas `SA-noft2-Edwards` and `SA-noft2-BCM` should not have the ft2 term, and they are usually not combined with other corrections (see TMR for more details). To use non-standard combinations it is necessary to add `EXPERIMENTAL` to the option list, e.g. `SA_OPTIONS= NEGATIVE, BCM, EXPERIMENTAL`. + +The rough wall correction is implicitly turned on by specifying roughness values for wall markers via the `WALL_ROUGHNESS` option. + +### Shear Stress Transport (SST) ### + +SU2 implements the "Standard" (1994) and 2003 versions of the SST model along with several modifications. + +**Note:** Currently all versions are "modified" i.e. the turbulence kinetic energy (TKE) is not included in the viscous stress tensor. + +The main model is selected using `KIND_TURB_MODEL= SST` and the version and modifications via the `SST_OPTIONS` list. If this list is empty SU2 defaults to the baseline 1994 model, `V1994m` (see warning below). The options allow for a version and a set of modifiers to the version. +The freestream and inlet conditions are specified via the options `FREESTREAM_TURBULENCEINTENSITY= 0.05` (5%) and `FREESTREAM_TURB2LAMVISCRATIO= 10` (ratio of turbulent to laminar viscosity). + +**Note:** The default values for these options are suitable for internal flows but may be too high for external aerodynamics problems. + +The following modifications are allowed: +- Versions: + - `V1994m` - SSTm **WARNING:** Our implementation has a small [inconsistency with the literature](https://github.com/su2code/SU2/issues/1551), which will be resolved in the next major SU2 update (i.e. version 8). + - `V2003m` - SST-2003m (no known inconsistencies). +- Production modifications: + - `VORTICITY` - Uses vorticity to compute the source term instead of strain-rate magnitude. + - `KATO_LAUNDER` - Uses the Kato-Launder modification (vorticity times strain-rate). + - `UQ` - Production is computed using a modified stress tensor for [uncertainty quantification](https://su2code.github.io/tutorials/UQ_NACA0012/). **Note** with this modification TKE is always included in the stress tensor. +- Corrections: + - `SUSTAINING` - SST with controlled decay. + - Curvature corrections are currently not implemented. + +Modifications from each of these three groups can be combined, for example `SST_OPTIONS= V2003m, VORTICITY, SUSTAINING` diff --git a/_docs_v7/Theory.md b/_docs_v7/Theory.md index 1078d5c4..72b01dd9 100644 --- a/_docs_v7/Theory.md +++ b/_docs_v7/Theory.md @@ -164,9 +164,10 @@ Within the `INC_EULER` solver, we discretize the equations in space using a fini # Turbulence Modeling # -The Shear Stress Transport (SST) model of Menter and the Spalart-Allmaras (S-A) model are two of the most common and widely used turbulence models. The S-A and SST standard models, along with several variants, are implemented in SU2. The reader is referred to the [NASA Turbulence Modeling Resource](https://turbmodels.larc.nasa.gov/index.html) (TMR) for the details of each specific model, as the versions in SU2 are implemented according to the well-described formulations found there. +SU2 implements several variants of the SST and SA turbulence models, for specifics of the models please see the [NASA Turbulence Modeling Resource](https://turbmodels.larc.nasa.gov/index.html) (TMR). +For information on how to use turbulence models in SU2 see the [users guide](https://su2code.github.io/docs_v7/Physical-Definition/). -Within the turbulence solvers, we discretize the equations in space using a finite volume method (FVM) with a standard edge-based data structure on a dual grid with vertex-based schemes. The convective and viscous fluxes are evaluated at the midpoint of an edge. +The edge-based finite volume discretization of flow solvers is also used in turbulence solvers. Convective fluxes are evaluated using a scalar upwind scheme (1st or 2nd order). --- diff --git a/_tutorials/compressible_flow/Transitional_Flat_Plate/Transitional_Flat_Plate.md b/_tutorials/compressible_flow/Transitional_Flat_Plate/Transitional_Flat_Plate.md index 11160a89..639d4de2 100644 --- a/_tutorials/compressible_flow/Transitional_Flat_Plate/Transitional_Flat_Plate.md +++ b/_tutorials/compressible_flow/Transitional_Flat_Plate/Transitional_Flat_Plate.md @@ -62,17 +62,17 @@ Several of the key configuration file options for this simulation are highlighte % LINEAR_ELASTICITY, POISSON_EQUATION) SOLVER= INC_RANS % -% Specify turbulent model (NONE, SA, SA_NEG, SST) +% Specify turbulent model (NONE, SA, SST) KIND_TURB_MODEL= SA % -% Specify transition model (NONE, BC) -KIND_TRANS_MODEL= BC +% Specify transition model +SA_OPTIONS= BCM % % Specify Turbulence Intensity (%) FREESTREAM_TURBULENCEINTENSITY = 0.18 ``` -The governing equations are RANS with the Spalart-Allmaras (`SA`) turbulence model. By entering `KIND_TRANS_MODEL= BC`, the Bas-Cakmakcioglu Algebraic Transition Model is activated. This model requires freestream turbulence intensity that is to be used in the transition correlation, thus the `FREESTREAM_TURBULENCEINTENSITY` option is also used. The BC model achieves its purpose by modifying the production term of the 1-equation SA turbulence model. The production term of the SA model is damped until a considerable amount of turbulent viscosity is generated, and after that point, the damping effect on the transition model is disabled. Thus, a transition from laminar to turbulent flow is obtained. +The governing equations are RANS with the Spalart-Allmaras (`SA`) turbulence model. By entering `SA_OPTIONS= BCM`, the Bas-Cakmakcioglu Algebraic Transition Model is activated. This model requires freestream turbulence intensity that is to be used in the transition correlation, thus the `FREESTREAM_TURBULENCEINTENSITY` option is also used. The BC model achieves its purpose by modifying the production term of the 1-equation SA turbulence model. The production term of the SA model is damped until a considerable amount of turbulent viscosity is generated, and after that point, the damping effect on the transition model is disabled. Thus, a transition from laminar to turbulent flow is obtained. The incompressible freestream properties are specified as follows. (Please see "Notes" for freestream properties of other transitional flat plate test cases).