$$$$ SPAL NOTICE CHAT 11/09/12 21:18:10 7124 DATE 11/09/12 Procedure SPAL Voir aussi : KEPSILON SYNTAXE (cf. operateur EQEX) ____________________________ 'ZONE' $MD 'OPER' 'SPAL' 'RHO' 'UN' 'MU' 'DT' ('PERIODIC' GEOM1 GEOM2) 'INCO' 'NU0' Description : _____________ Computes the dynamic eddy viscosity according to the Spalart-Allmaras turbulence model Comments : __________ 1) REQUIRED PARAMETERS are: RHO*[MOT|FLOTTANT|CHPOINT] : Mass per unit volume (kg/m3) UN *[MOT|CHPOINT] : Advection velocity (m/s) MU *[MOT|FLOTTANT|CHPOINT] : Dyn. molecular viscosity (Pa.s) DT *[MOT|FLOTTANT] : Time step duration (s) NU0*[MOT] : Name of the modified eddy viscosity A MOT-typed object means the actual value is searched for in the 'INCO' table. /!\ CAUTION: This model also requires the wall distance to be stored as a CHPOINT object in (RV.'PAROIS'.'DIST') !! 2) The computed total dynamic viscosity field (molecular + turbulent) can be found in the 'INCO' table under the default 'MUFN' index. This name is customizable (see comment 4 for advanced parameters) /!\ CAUTION: Dirichlet boundary conditions and initial conditions have to bear upon 'NU0' exclusively !! 3) OPTIONAL KEYWORD 'PERIODIC' sets periodic conditions upon 'MUFN' between GEOM1 and GEOM2. 4) ADVANCED PARAMETERS can be customized by creating a TABLE object in (RV.'SPALART_ALLMARAS') : +----------------------------------------------------------------+ | MAIN TABLE 'SPALART_ALLMARAS' | +-----------+-----------+----------------------------------------+ | Index | Value | Description | +-----------+-----------+----------------------------------------+ | 'KVERS' | [MOT] | Model version to be used: | | | 'ORIG' | - Baseline original model (default) | | | 'TRIP' | - Original model with ft1 and ft2 | <= TO DO | | 'SALSA' | - Strain-Adaptive Model by Rung et al. | <= TO DO | | | | | 'NOMMUF' | MOT | Name given to the total viscosity | | | | ('MUFN' by default) | | | | | | 'KCONST' | TABLE | Model constants | | | | | | 'KTGRAD' | [MOT-cle] | Gradient tensor scalar measure: | | | 'TOROT' | - Rotation rate (default) | | | 'TODEF' | - Strain rate | | | 'COMPL' | - Norm of the full tensor | | | 'MIXTE' | - Formula by Dacles-Mariani et al. | | | | | | 'KMUFN' | [MOT-cle] | Return value for 'MUFN' : | | | 'APRES' | - End of the time step (default) | | | 'AVANT' | - Beginning of the time step | | | 'DEMI' | - After the half time step ('ALGO1') | | | | | | 'KSRC' | [MOT-cle] | Algorithm for source terms | | | 'ALGO1' | - Newton method (default) | | | 'ALGO2' | - Linearization and S+/S- splitting | | | | | | 'NEWTON' | TABLE | Newton algorithm configuration whether | | | | 'KSRC' parameter is set to 'ALGO1' | | | | | | 'METHINV' | TABLE | Inversion method options. | | | | By default, they are the same as those | | | | defined for the global in the RV table | | | | | | 'KOPT2' | TABLE | Time discretization options. | | | | By default, parameters passed via EQEX | | | | 'OPTI' are applied to both TSCA & DFDT | | | | operators (except DFDT is set to | | | | 'CENTREE' by default) | | | | | | 'VERROU' | TABLE | Numerical limiters status | | | | | | 'DUMP' | LOGIQUE | Save the SA model internal variables | | | | in the 'INCO' table under the 'SPAL' | | | | index? (Default: FAUX) | +-----------+-----------+----------------------------------------+ +----------------------------------------------------------------+ | SUBTABLE 'KCONST' | +-----------+-----------+----------------------------------------+ | Index | Value | Description | Defau. | +-----------+-----------+-------------------------------+--------+ | 'SIGMA' | FLOTTANT | Prandtl turbulent number | 2/3 | | 'CB1' | FLOTTANT | Turbulent production rate | 0.1355 | | 'CB2' | FLOTTANT | Non-conservative diffusion | 0.622 | | 'KAPPA' | FLOTTANT | Von Karman constant | 0.41 | | 'CV1' | FLOTTANT | Visc. sublayer thick. (Low-Re)| 7.1 | | 'CW1' | FLOTTANT | Log lay. Prod/Dest equilibr. | 3.2391 | | 'CW2' | FLOTTANT | Friction factor control | 0.3 | | 'CW3' | FLOTTANT | Upper bound of fw (approx.) | 2. | +-----------+-----------+----------------------------------------+ +----------------------------------------------------------------+ | SUBTABLE 'NEWTON' | +-----------+-----------+----------------------------------------+ | Index | Value | Description | Defau. | +-----------+-----------+-------------------------------+--------+ | 'CRIT' | FLOTTANT | Stop criterion (infinity norm)| 1.E-10 | | 'IMAX' | ENTIER | Maximum number of iterations | 10 | | 'OMEGA' | FLOTTANT | Relaxation factor | 1. | +-----------+-----------+----------------------------------------+ +----------------------------------------------------------------+ | SUBTABLE 'VERROU' | +-----------+-----------+----------------------------------------+ | Index | Value | Description | Defau. | +-----------+-----------+-------------------------------+--------+ | 'POSITIF' | LOGIQUE | Force NU0 and S0 positiveness | VRAI | | 'DURBIN' | LOGIQUE | Durbin Realizability | FAUX | <= TO DO +-----------+-----------+----------------------------------------+ Complements : ABOUT THE AVAILABLE ALGORITHMS ____________ Source terms are non-linear and may become negative (at least in the baseline model). We implemented 2 algorithms to allow convergence: 'ALGO1' => Source terms are dealt with before convection/diffusion step (splitting method). An intermediate time step is reached by resolving only the source terms thanks to a Newton method. The remaining half time step then consists in the transport ODE resolution, without source terms. 'ALGO2' => The source terms negative component is linearized in order to be merged into the stiffness matrix (implicit) while the positive part stays at the right-hand side (explicit). The complete transport equation is then solved.
© Cast3M 2003 - All rights reserved.
Disclaimer