$$$$ TRAJ NOTICE CHAT 11/09/12 21:18:23 7124 DATE 11/09/12 Operateur TRAJ Voir aussi : -------------- Formulation finite element MODL4 MCH4 = TRAJ MOT1 |CHPO1| |TAB1 | ('PORO' MCH1) TAB2 ; |TAB4 | |MODL1| Formulation hybrid mixed finite element (DARCY) MODL4 MCH4 = TRAJ MOT1 MODL1 |CHPO2| ('PORO' MCH1) TAB2 ; |TAB5 | ('DISP' MCH2) ('DIFF' MCH3) Description : ------------- The TRAJ operator allows to calculate the trajectories of particles on a mesh on which we know a velocity field or a flux field. Comments : ---------- TAB1 is a TABLE type object, subtype DOMAINE. It is the result of the DOMA operator applied to the mesh on which we do the calculation. MOT1 mode of calculation 'CONVECTION_EXPLICITE' : particle positions are calculated step by step according to interpolated local velocity (default option), 'CONVECTION_ANALYTIQUE' : particle positions are obtained by analytical interpolation from entrance face to exit face of each element (only EFMH formulation), 'CONVECTION_DIFFUSION' : particle positions are calculated step by step according to interpolated local velocity and with random diffusive-dispersive jumps (available only for DARCY models). MODL1 modeled structure (MMODEL type) describing the formulation (cf. MODE). Only DARCY and NAVIER_STOKES models are accepted. CHPO1 velocity field defined at the nodes of TAB1.MAILLAGE. Its componentmust be VX VY (VZ). TAB4 is a TABLE type object, subtype TRANSITOIRE. It contents at index 'TEMPS' a TABLE of times (FLOTTANT), and at index 'VITESSE' a TABLE of velocity fields just like CHPO1. The indexes of this table are integers 0 1 2 ... N CHPO2 Contains the integrated flow field for each element's face. (CHPOINT type, based on FACE points, component 'FLUX') (see HDEB). TAB5 is a TABLE type object, subtype DARCY_TRANSITOIRE. It contents at index 'TEMPS' a TABLE of times (FLOTTANT), and at index 'FLUX' a TABLE of integrated flow field just like CHPO2. The indexes of this table are 0 1 2 ... N. (Cf. DARCYTRA). MCH1 porosity (MCHAML object, based on GRAVITE points, component 'SCAL'). When computing, the velocity will be divided by porosity. (Default value = 1.) MCH2 longitudinal and transversal dispersivity MCHAML object, based on GRAVITE points, two components, Default value = 0. for each, used only in the 'CONVECTION_DIFFUSION' mode. MCH3 effective isotropic diffusion : MCHAML object, based on GRAVITE points, one component, Default value = 0. used only in the 'CONVECTION_DIFFUSION' mode. TAB2 is a table with several indexes containing the description of starting points of particles. TAB2.'TEMPS_LIMITE' contains the maximal calculation time (FLOTTANT). TAB2.'CFL' contains the Courant Number ('FLOTTANT') to be respected. The calculation time step will depend on it. In the average, there will be 1/CFL internal particle jumps in each mesh. This number must be included between 1.E-8 and 1. Used only in the 'CONVECTION_EXPLICITE' mode. TAB2.'DELTAT_SAUVE' contain the saving time step ('FLOTTANT'). If equal to 0., it will be calculated automatically. TAB2.'TEMPS_SAUVES' contains the saving times 'LISTE' ('LISTREEL') This index and the previous index, 'DELTAT_SAUVE', must not exist at the same time. If none of them are defined, all the calculation times will be saved. Available only in the 'CONVECTION_DIFFUSION' mode. TAB2.'IMPERMEABLE' : mesh (MAILLAGE type, based on FACE points, 'POI1' elements) determining the impervious faces. Available only in the 'CONVECTION_DIFFUSION' mode. TAB2.'TEMPS_LACHER' : initial time of each release ('LISTREEL'). For each float in the list, there must be a corresponding release mesh (see below). TAB2.1 : mesh ('POI1' elements) containing the particle release points for the first time in TAB2.'TEMPS_LACHER' list " " " " " " TAB2.i : mesh ('POI1' elements) containing the particle release points for the ith time in TAB2.'TEMPS_LACHER' list. MODL4 : resulting model ('TRAJECTOIRE' formulation), concatenation of elementary models ; one for each trajectory. The associated meshes ('SEG2' elements) yield the particles positions (see 'EXTR' 'ZONE' and 'COOR' to get the coordinates). MCH4 : resulting MCHAML, based on the MODL4 model, based on the nodes (NOEUD) of each segment (SEG2) of the corresponding meshes. The 'TMPS' component contains the travel time. Example: (see valitraj.dgibi or trajec.dgibi) -------- si CARRE est un maillage et VN un champ de vitesse aux noeuds, et MODCAR un modele de type NAVIER_STOKES, on pourra coder la sequence suivante. * DEFINITION OF THE RELEASE TABLE LACHER = TABLE ; LACHER.TEMPS_LACHER = PROG 0. 2. ; LACHER.TEMPS_LIMITE = 180.; LACHER.CFL = 0.05 ; LACHER.DELTAT_SAUVE = 0. ; * first release at t=0. : LACHER.1 = (0.0 0.0) 'ET' (0.0 1.) 'ET' (0.0 2.0) ; * second release at t= 2. : LACHER.2 = 'MANU' 'POI1' (0.0 1.) ; * TRAJECTORIES CALCULATION MODL4 MCH4 = 'TRAJ' MODCAR VN LACHER ; * TRAJECTORIES DRAWING CROB = 'EXTR' MODL4 'MAIL' ; 'TRACER' CROB ; * TRAVEL TIME DRAWING ALONG TRAJECTORIES 'TRACER' MCH4 MODL4 ; * EXIT TIME OF THE FIRST TRAJECTORY TABZON = 'EXTR' MODL4 'ZONE' ; NBB = 'NBEL' TABZON . 2 ; TT1 = 'EXTR' MCH4 'TMPS' 1 NBB 2 ; 'LISTE' TT1 ; Notes : ------- 1. The mesh elements which can be used now are in 2D TRI3 QUA4 in 3D PRI6 CUB8 TET4 2. The Courant Number is used to calculate the internal time step in each encountered cell with the formula dt = (L * C) / Vm where L is twice the smalest distance between the center and the face points of the cell, Vm is the average microscopic velocity in the cell, dt is the time step. C is the Courant number. C must be small enough to allow several step in each cell. Validation tests have been made using C=0.05 . 3. When TAB2.'DELTAT_SAUVE' is different from 0., particle positions are saved using the given time gap. However, if the particle exists the domain between two save times, the exit time and positions will be also kept. 4. In the case of transient flow, velocity and fluxes are linearly interpolated with respect to time.
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