Difference between revisions of "Lake Jersey Refinement Example AB"

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This example is a simple refinement application with two grids: coarse ('''A''') and fine ('''B''').  There are two nesting layers because two different time-step sizes are required in [[ocean_lake_jersey_nested_2g_ab.in]]:
This example is a simple refinement application with two grids: coarse ('''A''') and fine ('''B''').  There are two nesting layers because two different time-step sizes are required in [[ocean_lake_jersey_nested_2g_ab.in]]:


* Number of nested grids.<div class="box">      [[Ngrids]] =  2</div>
* Number of nested grids.<div class="box">      [[Ngrids]] =  2</div>
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* Notice that since the coarse grid ('''A''') is an enclosed basin, all lateral boundary conditions on that grid are set to closed ('''Clo''') while the refined grid ('''B'''), which is entirely enclosed by the coarse grid, has nested ('''Nes''') lateral boundary conditions.<div class="box">  [[Variables#LBC|LBC(isFsur)]] ==  Clo    Clo    Clo    Clo \      ! free-surface,  Grid 1<br />                    Nes    Nes    Nes    Nes        ! free-surface,  Grid 2<br /><br />  [[Variables#LBC|LBC(isUbar)]] ==  Clo    Clo    Clo    Clo \      ! 2D U-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 2D U-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isVbar)]] ==  Clo    Clo    Clo    Clo \      ! 2D V-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 2D V-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isUvel)]] ==  Clo    Clo    Clo    Clo \      ! 3D U-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 3D U-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isVvel)]] ==  Clo    Clo    Clo    Clo \      ! 3D V-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 3D V-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isMtke)]] ==  Clo    Clo    Clo    Clo \      ! mixing TKE,    Grid 1<br />                    Nes    Nes    Nes    Nes        ! mixing TKE,    Grid 2<br /><br />  [[Variables#LBC|LBC(isTvar)]] ==  Clo    Clo    Clo    Clo \      ! temperature,  Grid 1<br />                    Clo    Clo    Clo    Clo \      ! salinity,      Grid 1<br />                    Nes    Nes    Nes    Nes \      ! temperature,  Grid 2<br />                    Nes    Nes    Nes    Nes        ! salinity,      Grid 2<br /></div>  
* Notice that since the coarse grid ('''A''') is an enclosed basin, all lateral boundary conditions on that grid are set to closed ('''Clo''') while the refined grid ('''B'''), which is entirely enclosed by the coarse grid, has nested ('''Nes''') lateral boundary conditions.<div class="box">  [[Variables#LBC|LBC(isFsur)]] ==  Clo    Clo    Clo    Clo \      ! free-surface,  Grid 1<br />                    Nes    Nes    Nes    Nes        ! free-surface,  Grid 2<br /><br />  [[Variables#LBC|LBC(isUbar)]] ==  Clo    Clo    Clo    Clo \      ! 2D U-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 2D U-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isVbar)]] ==  Clo    Clo    Clo    Clo \      ! 2D V-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 2D V-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isUvel)]] ==  Clo    Clo    Clo    Clo \      ! 3D U-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 3D U-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isVvel)]] ==  Clo    Clo    Clo    Clo \      ! 3D V-momentum, Grid 1<br />                    Nes    Nes    Nes    Nes        ! 3D V-momentum, Grid 2<br /><br />  [[Variables#LBC|LBC(isMtke)]] ==  Clo    Clo    Clo    Clo \      ! mixing TKE,    Grid 1<br />                    Nes    Nes    Nes    Nes        ! mixing TKE,    Grid 2<br /><br />  [[Variables#LBC|LBC(isTvar)]] ==  Clo    Clo    Clo    Clo \      ! temperature,  Grid 1<br />                    Clo    Clo    Clo    Clo \      ! salinity,      Grid 1<br />                    Nes    Nes    Nes    Nes \      ! temperature,  Grid 2<br />                    Nes    Nes    Nes    Nes        ! salinity,      Grid 2<br /></div>  


The following tables summarize the nested grids information:
The following tables summarize the nested grids information:


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Revision as of 23:01, 8 December 2014

Lake Jersey Nesting Refinement Example

Description

The Lake Jersey test case is primarily used to evaluate the nesting algorithms for the Refinement Grids Super-Class. It is activated with C-preprocessing options LAKE_JERSEY and NESTING. The nesting algorithms in ROMS are two-way by default. The option ONE_WAY can be used for just one-way exchange between donor (dg) and receiver (rg) grids. However, the one-way exchange has no effect whatsoever on the coarser donor grid because there is no feed back of information. Notice that due to its higher spatial and temporal resolutions, the finer grid is better resolving the physical phenomena at smaller scales.

This example is a simple refinement application with two grids: coarse (A) and fine (B). There are two nesting layers because two different time-step sizes are required in ocean_lake_jersey_nested_2g_ab.in:


  • Number of nested grids.
    Ngrids = 2
  • Number of grid nesting layers. This parameter is used to allow refinement and composite grid combinations.
  • Time-stepping parameters.
    NTIMES == 1440 4320  ! Number of time steps
    DT == 120.0d0 40.0d0  ! Time-step size (seconds)
    NDTFAST == 30 30  ! Number of barotropic steps
  • Input NetCDF file names, [1:Ngrids] values are expected. The order of the grids are extremely important in nesting applications.
    GRDNAME == ../Data/lake_jersey_grd_coarse.nc \
    ../Data/lake_jersey_grd_refined_bot.nc

    ININAME == ../Data/lake_jersey_ini_coarse.nc \
    ../Data/lake_jersey_ini_refined_bot.nc
  • Nesting grids connectivity data: contact points information. This NetCDF file is special and complex. It is currently generated using the script matlab/grid/contact.m from the Matlab repository.
    NGCNAME = ../Data/lake_jersey_ngc_2g_ab.nc
  • Notice that since the coarse grid (A) is an enclosed basin, all lateral boundary conditions on that grid are set to closed (Clo) while the refined grid (B), which is entirely enclosed by the coarse grid, has nested (Nes) lateral boundary conditions.
    LBC(isFsur) == Clo Clo Clo Clo \  ! free-surface, Grid 1
    Nes Nes Nes Nes  ! free-surface, Grid 2

    LBC(isUbar) == Clo Clo Clo Clo \  ! 2D U-momentum, Grid 1
    Nes Nes Nes Nes  ! 2D U-momentum, Grid 2

    LBC(isVbar) == Clo Clo Clo Clo \  ! 2D V-momentum, Grid 1
    Nes Nes Nes Nes  ! 2D V-momentum, Grid 2

    LBC(isUvel) == Clo Clo Clo Clo \  ! 3D U-momentum, Grid 1
    Nes Nes Nes Nes  ! 3D U-momentum, Grid 2

    LBC(isVvel) == Clo Clo Clo Clo \  ! 3D V-momentum, Grid 1
    Nes Nes Nes Nes  ! 3D V-momentum, Grid 2

    LBC(isMtke) == Clo Clo Clo Clo \  ! mixing TKE, Grid 1
    Nes Nes Nes Nes  ! mixing TKE, Grid 2

    LBC(isTvar) == Clo Clo Clo Clo \  ! temperature, Grid 1
    Clo Clo Clo Clo \  ! salinity, Grid 1
    Nes Nes Nes Nes \  ! temperature, Grid 2
    Nes Nes Nes Nes  ! salinity, Grid 2


The following tables summarize the nested grids information:


Grid Information
Grid ng Mesh
Size
Refinement
Factor(m)
Δx
Δy
dt
(s)
A 1 100x80 - 500 120
B 2 66x99 1:3 from A 166.6 40


Contact Region Information
cr dg rg
1 1 (A) 2 (B)
2 2 (B) 1 (A)


Results

The plots below show the results after 2 days of simulation for one-way and two-way nesting configurations. They are plotted with Matlab using the script plot_nesting.m. The refined solution (grid b) is overlayed on top of the coarse grid (a). The color map is rendered using shading flat, meaning there is no interpolation between pixels in the color maps. Click the figure to see a more detailed image. On the resulting page a link to the full resolution image is provided.