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Creating structured mesh in 2D using EASIFEM

· 4 min read
Vikas Sharma
Vikas Sharma
Assistant Professor, Kyoto University, Japan
Shion Shimizu
Shion Shimizu
Doctoral Student, Kyoto University, Japan

Creating a structured mesh of quadrangles​

To create a structured mesh of quadrangles in easifem, we will need following classes:

  • GmshStructuredMesh_Class: This is high-level interface on top of Gmsh library to create structured meshes.
  • Gmsh_Class: Interface to Gmsh library.
  • MSHFile_Class: Reading gmsh files
  • HDF5File_Class: Writing gmsh files to HDF5 file.

Very small mesh of quadrangles

PROGRAM main
USE GmshStructuredMesh_Class
USE Gmsh_Class
USE FPL
USE GlobalData
USE MSHFIle_Class
USE HDF5File_Class

IMPLICIT NONE

TYPE(GmshStructuredMesh_) :: obj
TYPE(Gmsh_) :: gmsh
TYPE(ParameterList_) :: param
! CHARACTER(*), PARAMETER :: title = "small_quad4_mesh"
CHARACTER(*), PARAMETER :: title = "very_small_quad4_mesh"
REAL(DFP), PARAMETER :: pointsOnAxis1(2) = [0.0, 1.0]
REAL(DFP), PARAMETER :: pointsOnAxis2(2) = [0.0, 1.0]

INTEGER(I4B), PARAMETER :: transfinitePointsOnAxis1(1) = [3]
INTEGER(I4B), PARAMETER :: transfinitePointsOnAxis2(1) = [3]

INTEGER(I4B) :: ierr

TYPE(MSHFile_) :: mshFile
TYPE(HDF5File_) :: hdf5file

CALL FPL_Init()
CALL param%Initiate()

CALL SetGmshStructuredMeshParam(param=param, &
                                filename=title//".msh", &
                                pointsOnAxis1=pointsOnAxis1, &
                                pointsOnAxis2=pointsOnAxis2, &
                          transfinitePointsOnAxis1=transfinitePointsOnAxis1, &
                          transfinitePointsOnAxis2=transfinitePointsOnAxis2, &
                                recombineAll=.TRUE.)

CALL obj%Initiate(param)

ierr = gmsh%initialize()
ierr = gmsh%model%add("GmshStructuredMesh2D")
CALL obj%Generate(gmsh)
! ierr = gmsh%fltk%run()
ierr = gmsh%finalize()

CALL param%DEALLOCATE()
CALL obj%DEALLOCATE()

CALL mshFile%Initiate(filename=title//'.msh', STATUS="OLD", ACTION="READ")
CALL mshFile%OPEN()
CALL mshFile%READ()
CALL hdf5file%Initiate(title//'.h5', MODE="NEW")
CALL hdf5file%OPEN()
CALL mshFile%Export(hdf5=hdf5file, group="")
CALL mshFile%DEALLOCATE()
CALL hdf5file%DEALLOCATE()

END PROGRAM main