GetFaceDOF

The GetFaceDOF generic method in the FEDOF_Class is used to retrieve the degrees of freedom (DOF) associated with a face in a finite element mesh. This method has two specific implementations with different parameter sets.

Method Description

The GetFaceDOF generic method retrieves face degrees of freedom through two different interfaces:

1. GetFaceDOF1 - Gets DOFs directly using a global face number
2. GetFaceDOF2 - Gets DOFs using a global element number and local face number within that element

Interface 1

SUBROUTINE obj_GetFaceDOF1(obj, globalFace, ans, tsize, islocal)

Parameters

• obj - Input, CLASS(FEDOF_), FEDOF object instance
• globalFace - Input, INTEGER(I4B), global face number
• ans - Output, INTEGER(I4B)(:), array to store face degrees of freedom
• tsize - Output, INTEGER(I4B), total size of data written to ans
• islocal - Optional Input, LOGICAL(LGT), if true, globalFace is treated as a local face number

Implementation Details

The implementation in GetMethods submodule uses the internal face index array structure:

INTEGER(I4B) :: ii
tsize = 0
DO ii = obj%faceIA(globalface), obj%faceIA(globalface + 1) - 1
  tsize = tsize + 1
  ans(tsize) = ii
END DO

The method retrieves DOFs from the face sparsity data structure using the compressed sparse row format stored in faceIA.

Interface 2

SUBROUTINE obj_GetFaceDOF2(obj, globalElement, localFaceNumber, ans, tsize, islocal)

Parameters

• obj - Input, CLASS(FEDOF_), DOF object
• globalElement - Input, INTEGER(I4B), global or local element number
• localFaceNumber - Input, INTEGER(I4B), local face number in global element
• ans - Output, INTEGER(I4B)(:), array to store face degrees of freedom
• tsize - Output, INTEGER(I4B), total size of data written to ans
• islocal - Optional Input, LOGICAL(LGT), if true, globalElement is treated as a local element number

Implementation Details

This implementation first converts the element and local face information to a global face number, then calls the first implementation:

INTEGER(I4B) :: globalFace
globalFace = obj%mesh%GetGlobalFaceNumber(globalElement=globalElement, &
                             islocal=islocal, localFaceNumber=localFaceNumber)
CALL obj%GetFaceDOF(globalFace=globalFace, ans=ans, tsize=tsize, &
                    islocal=islocal)

Usage Example

! Example to get DOFs from a face
INTEGER(I4B) :: faceDOFs(100), totalDOFs
TYPE(FEDOF_) :: myDOF

! Method 1: Using global face number
CALL myDOF%GetFaceDOF(globalFace=5, ans=faceDOFs, tsize=totalDOFs)

! Method 2: Using element and local face number
CALL myDOF%GetFaceDOF(globalElement=10, localFaceNumber=2, ans=faceDOFs, tsize=totalDOFs)

Related Methods

• GetTotalFaceDOF - Returns the total number of DOFs on a face
• GetEdgeDOF - Similar function but for element edges
• GetCellDOF - Gets DOFs for volumetric elements
• GetVertexDOF - Gets DOFs for element vertices

Need any additional details about these methods?

Example

!> author: Vikas Sharma, Ph. D.
! date: 2025-06-07
! summary:  Testing GetFaceDOF method of FEDOF class
! H1 Heirarchical Second Order Triangular Mesh

PROGRAM main
USE FEDOF_Class
USE FEDomain_Class
USE AbstractMesh_Class
USE HDF5File_Class
USE Display_Method
USE GlobalData
USE Test_Method
USE ExceptionHandler_Class, ONLY: e, EXCEPTION_INFORMATION
USE AppendUtility
USE ArangeUtility
USE ReallocateUtility

IMPLICIT NONE

CHARACTER(*), PARAMETER :: &
  filename = "../../FEMesh/examples/meshdata/small_tri3_mesh.h5", &
  baseContinuity = "H1", &
  baseInterpolation = "Heirarchical", &
  testname = baseContinuity//" "//baseInterpolation//" GetFaceDOF test"

TYPE(FEDOF_) :: fedof
TYPE(FEDomain_) :: dom
CLASS(AbstractMesh_), POINTER :: meshptr => NULL()
TYPE(HDF5File_) :: meshfile
INTEGER(I4B) :: order, totalVertexNodes, totalFaces
LOGICAL(LGT) :: isok

CALL e%SetQuietMode(EXCEPTION_INFORMATION, .TRUE.)

CALL meshfile%Initiate(filename, mode="READ")
CALL meshfile%OPEN()
CALL dom%Initiate(meshfile, '')
meshptr => dom%GetMeshPointer()
totalVertexNodes = meshptr%GetTotalVertexNodes()
totalFaces = meshptr%GetTotalFaces()

CALL test1
CALL test2
CALL test3

CALL dom%DEALLOCATE()
CALL meshfile%DEALLOCATE()

CONTAINS

!----------------------------------------------------------------------------
!                                                                      test1
!----------------------------------------------------------------------------

SUBROUTINE test1

  INTEGER(I4B) :: tsize, found(10), want(10)
  INTEGER(I4B), ALLOCATABLE :: con(:)

  order = 1
  CALL fedof%Initiate(baseContinuity=baseContinuity, &
                      baseInterpolation=baseInterpolation, &
                      order=order, mesh=meshptr)

  con = fedof%GetConnectivity(globalElement=1, islocal=.TRUE., opt="A")

  CALL fedof%GetFaceDOF(globalFace=1, islocal=.TRUE., &
                        ans=found, tsize=tsize)

  isok = tsize .EQ. 0
  CALL OK(isok, testname//" (order= "//ToString(order)//"): ")

  CALL fedof%GetFaceDOF(globalElement=1, islocal=.TRUE., &
                        ans=found, tsize=tsize, localFaceNumber=1)
  isok = tsize .EQ. 0
  CALL OK(isok, testname//" interface 2 (order= "//ToString(order)//"): ")

END SUBROUTINE test1

!----------------------------------------------------------------------------
!                                                                      test2
!----------------------------------------------------------------------------

SUBROUTINE test2

  INTEGER(I4B) :: tsize, found(10), want(10)

  order = 2
  CALL fedof%Initiate(baseContinuity=baseContinuity, &
                      baseInterpolation=baseInterpolation, &
                      order=order, mesh=meshptr)

  CALL fedof%GetFaceDOF(globalFace=1, islocal=.TRUE., &
                        ans=found, tsize=tsize)

  CALL IS(tsize, 1, testname//" (order= "//ToString(order)//"): ")
  CALL IS(found(1), 13, testname//" (order= "//ToString(order)//"): ")

  CALL fedof%GetFaceDOF(globalElement=1, islocal=.TRUE., &
                        ans=found, tsize=tsize, localFaceNumber=1)

  CALL IS(tsize, 1, testname//" (order= "//ToString(order)//"): ")
  CALL IS(found(1), 13, testname//" (order= "//ToString(order)//"): ")

END SUBROUTINE test2

!----------------------------------------------------------------------------
!                                                                     test3
!----------------------------------------------------------------------------

SUBROUTINE test3

  INTEGER(I4B) :: tsize, found(10), want(10)

  order = 3
  CALL fedof%Initiate(baseContinuity=baseContinuity, &
                      baseInterpolation=baseInterpolation, &
                      order=order, mesh=meshptr)

  CALL fedof%GetFaceDOF(globalFace=1, islocal=.TRUE., &
                        ans=found, tsize=tsize)

  CALL IS(tsize, 2, testname//" (order= "//ToString(order)//"): ")
  CALL IS(found(1), 13, testname//" (order= "//ToString(order)//"): ")

  CALL fedof%GetFaceDOF(globalElement=1, islocal=.TRUE., &
                        ans=found, tsize=tsize, localFaceNumber=1)

  CALL IS(tsize, 2, testname//" (order= "//ToString(order)//"): ")
  CALL IS(found(1), 13, testname//" (order= "//ToString(order)//"): ")

END SUBROUTINE test3

!----------------------------------------------------------------------------
!
!----------------------------------------------------------------------------

END PROGRAM main