Tuflow and estry manual Version 3

3.11.22D Cell Codes

Each cell in a 2D domain is assigned a code to indicate its role. It must have a value of one of the types in Table 4 .7. As of Build 2002 01 AC, the default code value is one (1) or “water”.

Commands used to modify the cell codes are Set Code, Read MI Code (or Read MI Code BC), Read MID Code in the .tgc file, and Read MI BC in the .tbc file automatically sets the Boundary Cell code of 2 along external boundaries.

Table 4.7 Cell Codes

Type	Code	Description
Null Cells	-1	Inactive cells used to deactivate cells within the active domain. Null cells are often preferred to land cells as they are not excluded when TUFLOW outputs in SMS format. For two simulations to be compared in SMS, they must have exactly the same mesh. If an area in a model is removed (eg. filling part of a floodplain), use null cells or raise the ground elevations in preference to using land cells so that the two simulations can be compared. Note: In earlier versions of TUFLOW null cells were used to indicate the outside side of an external boundary – this is no longer the case. Cells on the outside of a boundary can be either a land or a null cell.
Land or Redundant Cells	0	Land cells are cells that are totally removed from the computation. The name “land” comes from coastal hydraulic studies where the land was the permanently dry area. Maximising the area of land cells reduces computation time and output file sizes.
Water or Active Cells	1	Water cells are active cells that can wet and dry.
Boundary Cells	2	Boundary cells indicate water cells that have an external boundary (including some types of 2D/1D dynamic links). At an external boundary there must be a water cell on one side and a null or land cell on the other. Note: It is not necessary to manually specify each boundary cell. Boundary lines are digitised in the GIS and TUFLOW automatically assigns the boundary code to the cells (see Section 3.17.7 and Read MI BC).