Opened 2 years ago

Closed 2 years ago

#780 closed upgrade (Done)

IMPORTANT: Updated nesting Matlab script grid_connections.m

Reported by: arango Owned by:
Priority: major Milestone: Release ROMS/TOMS 3.7
Component: Matlab Version: 3.7
Keywords: Cc:

Description

The Matlab script used to compute nested grid connectivity (grid_connections.m) was updated, so it is more robust in telescoping nesting applications.

Currently, in ROMS a telescoping grid is a refined grid (refine_factor > 0) containing a finer grid inside. Notice that under this definition the coarser grid (ng=1, refine_factor=0) is not considered a telescoping grid. The last cascading grid is not considered a telescoping grid since it does not contains a finer grid inside. The telescoping definition is a technical one, and it facilitates the algorithm design.

A tricky algorithm is added at the top of these function to reject indirect connectivity in telescoping refinement. Previously, only one coincident connection between grids was allowed, as shown below:

http://www.myroms.org/trac/grids_1-and-2.png http://www.myroms.org/trac/grids_2-and-3.png http://www.myroms.org/trac/grids_1-and-3.png

Here, we have a three nested grid application. Grid-2 is a 1:3 refinement from Grid-1 and Grid-3 is a 1:3 refinement from Grid-2. The Grid-2 is the only telescoping grid in this application according to the above definition. Notice that Grid-3 is inside both Grid-2 (directly) and Grid-1 (indirectly).

The panels show the location of the donor grid (blue plus) and receiver grid (red circle) at PSI-points. Notice that in the top panel, the Grid-2 perimeter lies in the same lines as the donor Grid-1, and some of the points are coincident, as it should be. The same occurs in the middle panel between Grid-2 and Grid-3.

However, we did not allow before to have coincident grid points between the indirect connections of Grid-1 and Grid-3. We were using that property to reject indirect connections between nested grids.

I was aware of this restriction but I forgot to go back and code a robust logic in grid_connections.m to allow coincident grids points in indirect connections for telescoping applications. The restriction is removed with this update/

I know, it is a complicated subject to discuss with words. It needs to be shown geometrically.

Many thanks to Marc Mestres and John Wilkin for bringing this problem to my attention.

Change History (1)

comment:1 Changed 2 years ago by arango

  • Resolution set to Done
  • Status changed from new to closed
Note: See TracTickets for help on using tickets.