CFD DATABASE

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===== 3D AHMED-BODY FLOW at $Re_H= 10000$ =====


**Author** :  Y. Fraigneau  CNRS-LIMSI (yann.fraigneau@lisn.fr) \\
**Date**   :  July 2018\\
**Simulation type** : DNS ([[https://sunfluidh.lisn.upsaclay.fr|Sunfluidh code]]) \\
**Location** : DATABASE_AHMEDBODY_RE10000_DNS \\
** Status ** : Restricted access \\
**Data size** : ~ 609 Gb \\

{{ :datasetmeca:fig_ahmedbody_snapshot.png?1000 |}}

[[https://sunfluidh.lisn.upsaclay.fr/doku.php?id=sunfluidh:sunfluidh_gallery#_dmovie_cav3d_r2_re7826_fsview_mq.mp4| Videos are available here ]]

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==== Simulation settings ====
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=== 2D Sketch ===

{{ :datasetmeca:ahmedbody_sketch.jpg?800 |}}

=== Referential : cartesian geometry ===
   - axes   :
      * x : downstream direction
      * y : normal direction
      * z : spanwise direction
    - origin :
      * $x_0= 0$ : upstream edge of Ahmed body top
      * $y_0= 0$ : Ahmed body top
      * $z_0= 0$ : mid-span of domain

===  Reference scales ===

   * Density           : mass density of the fluid ($\rho_0$)
   * Length            : Ahmed body height ($H$)
   * Velocity          : inlet bulk velocity ($U_0$)
   * Dynamic viscosity : dynamic viscosity of the fluid ($\mu_0$)
   * Reynolds number : $Re_H= \frac{\rho_0.U_0.H}{\mu_0}= 10000$

=== Non-dimensionalised data ===

   * velocity   : $U^*=\frac{U}{U_0}$ 
   * density    : $\rho^*= \rho/\rho_0= 1$
   * coordinates : $x*=\frac{x}{H}$, $y^*=\frac{y}{H}$ , $z^*=\frac{z}{H}$

=== Computational domain ===

   - **Domain scope**
    * Downstream direction(x) : $L_t^*= 10.5$
    * Normal direction    (y) : $H_t^*= 2.5$
    * Spanwise direction  (z) : $W_t^*= 3.718$
    * Ahmed body size  : $L^*\times W^*\times H^* = 3.784 \times 1.178 \times 1$
    * Quarter rounded edges radius around the front face of the body : $R^*=0.347$
    * Ground clearance : $Hg^*= 0.334$
  - **Boundary conditions**
      * Inlet           : Uniform profile at $X_{in}^*= -1.0$
      * Outlet          : Orlansky's type at $X_{out}^*= 9.5$
      * Wall conditions : Ahmed body, top and low walls of the domain
      * Symmetry        : lateral ends of the domain
  - **Spatial resolution**   :
       * Grid   :  $512 \times 256 \times 256$ (33.554.432 cells)
       * About cell-size   
          * $\Delta x_{min}^*= 1 \, 10^{-2} \quad \Delta x_{max}^*= 3.03588 \,10^{-2}$ (downstream direction)
          * $\Delta y_{min}^*= 2 \, 10^{-3} \quad \Delta y_{max}^*= 4.12564 \,10^{-2}$ (normal direction)
          * $\Delta z_{min}^*= 2 \, 10^{-3} \quad \Delta z_{max}^*= 4.59486 \,10^{-2}$ (spanwise direction)

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==== Data features ====
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   * **Time series from probes** 
      * Physical quantities : velocity components along x, y and z directions (u,v,w) and pressure (p)
      * 3 probes
      * Time step= $5.5 \,10^{-3}$ time unit
      * Time range : 71 to  303, 343 to 680, 680 to 729, 729 to 780 time units
      * Locations (In horizontal mid-plan of the body wake)
          * Xi= 4.384 , Xj=-0.5 , Xk= 0.3
          * Xi= 4.384 , Xj=-0.5 , Xk= 0.0
          * Xi= 4.384 , Xj=-0.5 , Xk=-0.3
      * File name (per physical quantity): x_ins_00000.d   with x= u,v,w,p

   * **3D snapshots**
         * Instantaneous fields : velocity components along x,y and z directions (U,V,W) and pressure (P)
         * Recording rate : 0.5 time unit
         * Time range from from 185 to 780 time units
         *  File name : res_xxxxx_yyyyyyy.d  (xxxxx : MPI subdomain ID, yyyyyyy : Time ID)
               * MPI subdomain ID= 0 (No domain decomposition)
               * Time ID : 178 to 1364

   * **Statistics** 
      * fields : (i,j : indexes of direction x, y or z)
            * Mean fields of velocity components (<Ui>) and pressure (<P>)
            * Mean fields of quadratic quantities (<P2>, <UiUj>)
      * Time startup        = 43 time units
      * Time range per file = 10 time units
      * Total time range    from  43  to 780 time units
      * file name : rst_xxxxx_yyyyyyy.d  (xxxxx : MPI subdomain ID, yyyyyyy : Time ID)
            * MPI subdomain ID= 0 (No domain decomposition)
            * Time ID : 1 to 73

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==== Database organisation ====
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**Data size** : ~ 802 Gb \\
**Main directory** : /vol/DATABASE_MECA/RESTRICTED_ACCESS/DATABASE_AHMEDBODY_RE10000_DNS \\
For more details about files, see the [[https://sunfluidh.limsi.fr| wiki doc of Sunfluidh]]

=== Directories & files ===

    /GRID : contains all files about grid setup
    
       input data file         : data_meshgen.d
       report on grid features : report_meshgen.d
       grid files for sunfluidh: maillx.d, mailly.d, maillz.d
       check files (ASCII)     : check_mesh_I.d,check_mesh_J.d,check_mesh_K.d
                                 (3 columns : indices, cell-face coordinates, cell size)
                                 
    /DATASETUP       : it contains input data file for sunfluidh : input3d.dat
    
    /TIMESERIES : contains time series recorded from probes
                  /TIMESERIES_T071-305  : from time= 71 to 303 time units
                  /TIMESERIES_T343-533  : from time=343 to 533 time units
                  /TIMESERIES_T533-638  : from time=533 to 638 time units
                  /TIMESERIES_T638-680  : from time=638 to 680 time units
                  /TIMESERIES_T680-729  : from time=680 to 729 time units
                  /TIMESERIES_T729-780  : from time=729 to 780 time units
                      ASCII files : x_ins_00000_full.d   with x= u,v,w,p
                      also contains the space-averaged kinetic energy from time=326 to 561 (time step : 2.55D-02)
                      ASCII file : space_averaged_ke.d
    
    /SNAPSHOTS  : snapshots binary files res_xxxxx_yyyyyyy.d
                 
    /STATISTICS : statistics binary files rst_xxxxx_yyyyyyy.d
                 
    /RESTART_AR : backup/restart archives save_t361.tar, save_t561.tar, save_t638.tar, save_t729.tar, save_t780.tar
                  contains any file to resume the simulation at time = 361, 561, 638, 729 and 780 time units
    
    /FROM_COMPUTATION : regroup some directories and files related to the simulation
     
    /SLICES     : slices ... not documented  (old study)
                  Binary files : plan_id_dir_xxxxx_yyyyyyy.d
                 (nn : slice ID, dir : orientation, xxxxx : MPI subdomain ID, yyyyyyy : Time ID)

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