Spatial diffsion over a grid: using an array to handle interactions between cells

Model : gridspread1
Simile version : 3.1+
Date added : 2003-06-20
Keywords : Submodel ; Multi-instance submodel ; Spatial modelling ;

Description

This simulates diffusion over a grid of cells. We use a multiple-instance submodel to represent the set of cells. Each cell has a unique (row,column) attribute. The amount of substance flowing out of each cell is held outside the submodel in an array (with as many elements as there are cells), and this is used to calculate the amount flowing into neighbouring cells.

Files

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gridspread1.sml

Diagram

Equations

Equations in ../Desktop
  interflows = [outflow]/8 
   where: [outflow] = cell/outflow]
  rows = [row]
   where: [row] = cell/row
  cols = [col]
   where: [col] = cell/col

Equations in cell
      inflow = sum(if abs([rows]-row)<1.5 and abs([cols]-col)<1.5 then [interflows] else 0)
   where: 
      [interflows] = ../interflows
      [rows] = ../rows,[cols] = ../cols
      outflow = 0.05*amount
  row = floor((index(1)-1)/10)+1
  col = index(1)-10*(row-1)
compartment:amount = (if index(1) == 35 then 100 else 0)

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