CFD DATABASE

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===== 3D backward-facing step flow at $Re_H= 6000$ =====

**Author** :  Y. Fraigneau, LISN, UMR CNRS 9015 (yann.fraigneau@lisn.fr) \\
**Date**   :  August 2018\\
**Simulation type** : DNS (code Sunfluidh [[https://sunfluidh.lisn.upsaclay.fr|Sunfluidh code]]) \\
**Location** : DATABASE_BACKWARDFACINGSTEPFLOW_RE6000_DNS \\
** Status ** : Restricted access \\
**Data size** : ~ 4.4 Tb \\

{{:datasetmeca:bfs_snap3000_isoq_ux.png?1000|}}
\\

[[https://sunfluidh.lisn.upsaclay.fr/doku.php?id=sunfluidh:sunfluidh_gallery| A video is available here ]] \\
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==== Simulation settings ====
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=== 2D sketch ===

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

=== Referential : cartesian geometry ===
   - axes   :
      * x(i) : downstream direction
      * y(j) : normal direction
      * z(k) : spanwise direction
    - origin :
      * $x_0= 0$ : the step
      * $y_0= 0$ : the bottom wall of the domain
      * $z_0= 0$ : the left side of the computational domain

===  Reference scales ===

   * Density           : mass density of the fluid ($\rho_0$)
   * Length            : step height ($H$)
   * Velocity          : inlet bulk velocity ($U_i$)
   * Dynamic viscosity : dynamic viscosity of the fluid ($\mu_0$)
   * Reynolds number : $Re_H= \frac{\rho_0.U_i.H}{\mu_0}= 6000$

=== Non-dimensionalised data ===

   * velocity   : $U^*=\frac{U}{U_i}$ 
   * 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) : $L^*= 36.0$
    * Normal direction    (y) : $H_t^*= 2.0$
    * Spanwise direction  (z) : $l^*= 2\pi$
    * Step position  : $L_s^*= 12.0$
    * Step height    : $H^*= 1$
  - **Boundary conditions**
      * Inlet           : Uniform profile at $X_{in}^*= -12.0$
      * Outlet          : Orlansky's type at $X_{out}^*= 24.0$
      * Wall conditions : Top and low walls of the domain
      * Periodicity     : lateral ends of the domain
  - **Domain decomposition (160 MPI subdomains)**
      * Along the downstream direction :
            * 12 (between the inlet and the outlet, above the step)
            *  8 (between the step and the outlet)
      * Along  the normal direction    : 4
      * Along the spanwise direction   : 4
      * 2D sketch of domain decomposition in a plan {xy} (MPI process distribution (1)) \\ 1 1 1 1 1 1 1 1 1 1 1 1 \\ 1 1 1 1 1 1 1 1 1 1 1 1 \\ 0 0 0 0 1 1 1 1 1 1 1 1 \\ 0 0 0 0 1 1 1 1 1 1 1 1 \\
  - **Spatial resolution**   :
       * Grid   :  $128 \times 64 \times 64$ per subdomain (83.886.080 cells over the domain)
       * About cell-size   
          * $\Delta x_{min}^*= 1.0 \, 10^{-3} \quad \Delta x_{max}^*= 2.456 \,10^{-2}$ (downstream direction)
          * $\Delta y_{min}^*= 1.1 \, 10^{-3} \quad \Delta y_{max}^*= 1.653 \,10^{-2}$ (normal direction)
          * $\Delta z_{min}^*=\Delta z_{max}^*= 2.4543 \, 10^{-3}$ (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)
      * 11 probes
      * Time step= 0.01 time unit
      * Time range : 200.0 to 513.3 time units
      * Locations (In vertical plan at $z=3.14$)
          * Xi=-4.00 , Xj= 1.50 , Xk= 3.14 - MPI Subdomain ID : 17
          * Xi=-2.00 , Xj= 1.50 , Xk= 3.14 - MPI Subdomain ID : 25
          * Xi= 0.10 , Xj= 1.00 , Xk= 3.14 - MPI Subdomain ID : 37
          * Xi= 4.00 , Xj= 1.00 , Xk= 3.14 - MPI Subdomain ID : 53
          * Xi= 4.00 , Xj= 0.01 , Xk= 3.14 - MPI Subdomain ID : 49
          * Xi= 6.00 , Xj= 1.00 , Xk= 3.14 - MPI Subdomain ID : 69
          * Xi= 6.00 , Xj= 0.01 , Xk= 3.14 - MPI Subdomain ID : 65
          * Xi= 8.00 , Xj= 1.00 , Xk= 3.14 - MPI Subdomain ID : 69
          * Xi= 8.00 , Xj= 0.01 , Xk= 3.14 - MPI Subdomain ID : 65
          * Xi=16.0 , Xj= 1.00 , Xk= 3.14 - MPI Subdomain ID : 117
          * Xi=16.0 , Xj= 0.01 , Xk= 3.14 - MPI Subdomain ID : 113   
      * File name (per physical quantity) : x_ins_yyyyy.d   with x= u,v,w,p and 'yyyyy' the MPI subdomain ID

   * **3D snapshots**
         * Instantaneous fields : velocity components in x, y and z directions (U,V,W) and pressure (P)
         * Recording rate : 0.1 time unit
         * Time range from from 185.3 to 513.3 time units
         * File name : res_xxxxx_yyyyyyy.d  (xxxxx : MPI subdomain ID, yyyyyyy : Time ID)
               * MPI subdomain ID: from 0 to 159
               * Time ID : from 186 to 3465

   * **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 and space average computation (along the spanwise direction)
      * Time startup        = 180.0 time units
      * Time range per file = 10.0 time units
      * Total time range    from  180.0  to 510.0 time units
      * file name : rst_xxxxx_yyyyyyy.d  (xxxxx : MPI subdomain ID, yyyyyyy : Time ID)
            * MPI subdomain ID : from 0 to 39  (MPI process rank where results about space average computation are stored)
            * Time ID : from 1 to 33

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==== Database organisation ====
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**Data size** : ~ 4.4 Tb \\
**Main directory** : /vol/DATABASE_MECA/RESTRICTED_ACCESS/DATABASE_BACKFACINGSTEPFLOW_RE6000_DNS \\
For more details about files, see the [[https://sunfluidh.limsi.fr| wiki doc of Sunfluidh]]

=== Directories & files ===

    /GRID : contains all ASCII 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       : ASCII files
     
     input data file for sunfluidh : input3d.dat
     data file for MPI subdomain distribution (MPI graphical topology): data_mpi_subdomain_layout.dat
    
    /TIMESERIES : contains time series recorded over the time range [200,513.3]
                  ASCII files : x_ins_yyyyy.d   with x= u,v,w,p
                  time series files are sliced in directories CAS-MPI160-n (n from 121 to 330)
                  WARNING : possible underlying of time series for these data couples :
                             n = (243,244)
                             n = (246,247)
                             n = (259,260)
                             n = (260-261)
     
                             The directory CAS-MPI160-260 contains 2 groups of
                             consecutive timeseries files placed in directories DIR-A and DIR-B
     
    /SNAPSHOTS  : snapshots binary files res_xxxxx_yyyyyyy.d
                  files stored in archive files : res_yyyyyyy.tar for each time ID
                 
    /STATISTICS : statistics binary files files rst_xxxxx_yyyyyyy.d
                  files stored in archive files : rst_z.tar , z is an ID number
                 
    /RESTART_AR : backup/restart archive save.tar at 513.27 time units
    
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