Nesting

Introduction

The 'Nesting' toolbox allows nesting an already existing finer model in a larger model to increase resolution in the area of interest. Differently from domain decomposition the two models can not run in parallel but boundary conditions from the coarser (overall) model need to be generated at first and then provided to the finer model. The general idea is that under Nesting – 1 a list of monitoring stations in the overall (coarser) model, needed for the interpolation of the boundary conditions, is generated. The actual boundaries of the nested (smaller / finer) model are generated by Nesting - 2 by interpolating the history files of the overall (coarser) model 

Procedure

The procedure to generate nested boundary conditions consists of few steps after both models have been

1. Create the overall (coarser) model
2. Create the smaller (finer) model
3. Open the smaller (finer) model
   1. Specify 'open' boundaries. 
   2. Change forcing to 'time series'
4. Open the larger (coarser) model (see Figure 1)
   1. Go to the Nesting toolbox and 'Nesting - 1'
   2. Specify the grid, enc and bnd file of the finer model. 
   3. Generate the 'admin' file by clicking on 'Make Observation Points'.
   4. Define the time step of the observation points
   5. Save all your Delft3D-FLOW files
   6. Run the coarser model
5. Open the smaller (finer) model (see Figure 2)
   1. Go to the Nesting toolbox and 'Nesting - 2'
   2. Specify the history and admin file.
   3. Click on 'Run Nesting'. Boundary conditions can be generated for the “Hydrodynamics” and also “Transport” (e,g, salinity).