Bathymetry file and Geometry Module

Discussion around MOHID GUI (managing projects, simulations, etc)
MOHID Beginner
Posts: 3
Joined: Thu Jan 01, 1970 00:00

Bathymetry file and Geometry Module

Postby » Fri May 07, 2010 14:32


The main aim is to simulate an imaginary set up, that consists of a 20m long, 1m wide and 1m high (free surface) flume with a particular bed topography and with a for now uniform velocity profile at the inflow boundary and a high salinity (jet-like) flow near the inflow boundary. The free surface water level in the flume stays constant with a water depth of 1m.

I created a grid.dat file generated by
Mohid Digital Terrain Creator. I tried to run a simple Mohid water case without turbulence and lagrangian modules). However, it keeps generating a 'new bathymetry' file and tells me to
modify the Nomfich.dat file and then re-run the model. I do this, but then the same happens again. I cannot seem to get passed this error.

Further, I don't understand the geometry module with regard to the amount of layers in the vertical. I want a very detailed picture of the dispersion of the high salinity flow, does that mean I have to increase my amount of layers in the vertical? So for instance divinding the 1m water depth that I have in 100 or more layers with a equidistant of 0.01m?
This is my geometry file (Note I have highlighted questions in the comments behind the parameters)!:

!FACES_OPTION : 1 !don't understand this parameter
ID : 1
LAYERS : 100
!LAYERTHICKNESS : 0.2 0.2 0.2 0.2 0.2 ! Is this needed when parameter EQUIDISTANT is set?

Thank you very much for your help.

MOHID Developer
Posts: 553
Joined: Thu Jan 01, 1970 00:00
Location: Instituto Superior Técnico - Technical University of Lisbon

Postby » Tue Jun 08, 2010 09:47

Hi Kate,

Can you post the bathymetry file please? If it's too big please send it to me by e-mail. My feeling is that there is some inconsistency in the grid/bathymetry file that it becomes inconsistent with the vertical grid.
MOHID corrects the bathymetry based on the vertical grid, so that the bottom layer is not too thin.

MININITIALLAYERTHICKNESS controls this as it is the coefficient which indicates the minimal thickness in % of the bottom cells if

MinInitialLayerThickness = 1 - classic cartesian coordinat
if < 1 - cartesian with shave cells

In cartesian coordinates the reference layer thickness is computed for the maximum depth.



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