cpraveen / ug2lib

A small library to read 2d grids in Gmsh format and process them

A library for handling 2-D unstructured grids

At present the library supports reading only gmsh grids consisting of linear elements of triangles and quadrilaterals. The mesh can consist of both types of cells. It uses the older version of Gmsh grid format, so set

Mesh.MshFileVersion = 2.2;

in your geo file. Or specify the format on the command line

gmsh -2 -format msh22 foo.geo -o foo.msh

• src/main.cc : test grid preprocessor
• src/ccfv1.cc: first order FV code
• src/ccfv2.cc: second order FV code

Test the grid preprocessor

cd src
make
cd ../tests
gmsh -2 -format msh22 cylinder.geo
../src/main

See the output files cylinder.vtk and test_msh.msh.

visit -o cylinder.vtk
gmsh test_msh.msh

Test first order FV code: src/ccfv1.cc

cd tests
gmsh -2 -format msh22 square_tri.geo -o ccfv1.msh
../src/ccfv1
visit -o sol*.vtk

Test second order FV code: src/ccfv2.cc

This code reads some parameters from an input file, see tests/input.txt file. Several problems are defined in the code, compile them like this

make ccfv2 PROBLEM=CONT_ROT
make ccfv2 PROBLEM=DISC_ROT
make ccfv2 PROBLEM=PERIODIC_X   # enable periodic in geo file
make ccfv2 PROBLEM=PERIODIC_XY  # enable periodic in geo file

Formatting using astyle

Run astyle on source code before committing it

astyle --options=./astyle.rc grid.cc

or

sh ./astyle.sh

References

To understand the methods used in this code, you can refer to the following two books.

• Rainald Lohner: Applied Computational Fluid Dynamics Techniques
• Jiri Blazek: Computational Fluid Dynamics

Authors

• Shashwat Tiwari
• Praveen Chandrashekar