Module Geometry

Overview

Module Geometry handles the vertical discretization in MOHID. It was designed to divide the water column (in MOHID Water) or the soil compartment (in MOHID Land) in different vertical coordinates: Sigma, Cartesian, Lagrangian, Fixed Spacing, Harmonic, etc. A subdivision of the vertical domain into different sub-domains using different vertical coordinate systems is also possible.

General options

• Minimum depth

Vertical coordinate system

Sigma

Vertical sigma mesh

Cartesian

The Cartesian coordinate can be used with or without shaved cells.

Fixspacing

The Fixed Spacing coordinate allows the user to study flows close to the bottom.

Lagrangian

The Lagrangian coordinate moves the upper and lower faces with the vertical flow velocity.

Harmonic

The Harmonic coordinate works like the Cartesian coordinate, just that the horizontal faces close to the surface expand and collapse depending on the variation of the surface elevation. This coordinate was implemented in the geometry module to simulate reservoirs.

Distances

MOHID syntax for distances

Public routines

ModuleHorizontalGrid

GetHorizontalGrid(HorizontalGridID, XX_IE, YY_IE, XX_Z, YY_Z,XX_U, YY_U, XX_V, YY_V, XX_Cross, YY_Cross, DXX, DYY, DZX, DZY, DUX, DUY, DVX, DVY, XX, YY, XX2D_Z, YY2D_Z, STAT)

ModuleGeometry

GetGeometryDistances(GeometryID, SZZ, DZZ, DWZ, DUZ, DVZ, DZI, DZE,ZCellCenter, ActualTime, STAT)

Volumes

Single T-cell control volume

Bathymetry consistency diagnostic

Once the vertical discretization is imposed and the bathymetry is chosen, the bottom layer can yield stability problems when using shaved cells. You can have very thin bottom cell next to a very wide bottom cell. To diagnose the existence of such problematic cells, a geometry diagnostic tool was developed.