NEMOH-Toolbox

Mesh manipulation in Python with MESHMAGICK

Meshmagick is a command line utility as well as a python module for the manipulation of meshes encountered in the hydrodynamics community.

Its primary goal was to be a conversion tool between major file formats for hydrodynamic computations tools (Nemoh, Wamit, Hydrostar or Diodore) and visualization tools (stl, Tecplot, Paraview). It will be particularly useful for code to code comparisons or benchmarking.

Meshmagick also comes with several mesh manipulation capabilities: translation, rotation, scaling, clipping by a plane, symmetry, normals flipping, normals healing (making them consistent across the mesh and outgoing), cleaning (duplicate nodes merging...).

As of the release 1.0, meshmagick provides useful options for hydrostatics computations. It can solve for hydrostatics equilibrium for a given mass, center of gravity or both and provide the clipped mesh to be used by BEM software as well as the hydrostatics parameters (stiffness matrix, position of the center of buoyancy, displacement, draft...).

Meshmagick is primarily a command line utility for everyday hydrodynamicists. However, it also comes with a package that can be imported in a python script and give the full access to the command line options, programmatically.

The project is open source (under GPLv3 Licence).
Link for download: https://github.com/LHEEA/meshmagick
Documentation: https://lheea.github.io/meshmagick/

Mesh conversion in Matlab

Converting a NEMOH mesh to WAMIT

NEMOH mesh files may be converted to WAMIT .gdf files. One may use the nemoh2wamit_01a.m Matlab routine to do so. The routine has been developed and made available to the community by G. Payne who is with Edinburgh University.

Using a WAMIT mesh with NEMOH

WAMIT .gdf mesh files may be used with NEMOH. One may use the GDFMesh.m Matlab routine to do so. The routine has been developed and made available to the community by L. Banos.

Alternatively, one may use the runNemoh.m Matlab routine, which allows running NEMOH with .gdf files and only one routine. The routine has been developed and made available to the community by M. Thott Andersen.

Mesh conversion from opensource Salome-Meca framework to NEMOH

This script may be used to convert meshes created in the opensource Salome-Meca framework to NEMOH format. The routine has been developed and made available to the community by P. Schmitt who is with Queen’s University Belfast.

Mean horizontal drift forces

A Matlab routine has been developed in order to calculate the mean horizontal drift forces on a body using the far field approach (Maruo,1960 and Newman,1967). The routine has been developed and made available to the community by V. Arnal (with update on Nov. 27, 2016).

NEMOH to Orcaflex

A Matlab routine has been developed in order to export NEMOH’s outputs in Orcaflex’s format. The routine has been developed and made available to the community by V. Arnal.

State space approximation of impulse responses

Jose A. Armesto from University of Cantabria translated the Perez and Fossen Matlab toolbox into Pyth It can be downloaded here.

Wave-to-Wire models of wave energy converter using NEMOH for the calculation of hydrodynamic coefficients

Tim Verbrugghe from Ghent University has developed openWEC, an open source wave energy converter simulation tool. It includes NEMOH for the calculation of the hydrodynamic coefficients.