STConvectiveMatrix example 2

!!! note "" This example shows how to USE the SUBROUTINE called ConvectiveMatrix to create a space-time convective matrix. Line2 in space and time.

Here, we want to DO the following.

$$M\left( {I,J,a,b} \right) = {\int_{{I_n}}^{} {\int_\Omega ^{} {{c_j}\frac{{\partial {N^I}{T_a}}}{{\partial {x_j}}} \cdot {N^J}{T_b}d\Omega dt} } }$$ $$M\left(I,J,a,b\right)=\int_{I_{n}}\int_{\Omega}N^{I}T_{a}c_{j}\frac{\partial N^{J}T_{b}}{\partial x_{j}}d\Omega dt$$

!!! warning "" $c$ is convective velocity, which can be a constant, or a FUNCTION of space-time, or some nonlinear FUNCTION.

In this example, convective matrix is formed for

• [[ReferenceLine_]] Line2 element for space
• [[ReferenceLine_]] Line2 element for time
• [[QuadraturePoint_]] GaussLegendre
• nodal velocity, constant in time

Modules and classes

• [[ElemshapeData_]]

Usage

PROGRAM main
    USE easifemBase
    IMPLICIT NONE
    TYPE(STElemshapeData_), ALLOCATABLE :: test(:)
    TYPE(ElemshapeData_) :: time_elemsd
    TYPE(Quadraturepoint_) :: quadFortime
    TYPE(Quadraturepoint_) :: quadForspace
    TYPE(ReferenceLine_):: refelemForSpace
    TYPE(ReferenceLine_) :: refelemForTime
    INTEGER(I4B) :: ii
    INTEGER(I4B), PARAMETER :: nsd=1, nns=2, nnt=2
    INTEGER(I4B), PARAMETER :: orderForTime=2, orderForSpace=1
    REAL(DFP), PARAMETER :: tij(1, 2) = RESHAPE([-1,1], [1,2])
    REAL(DFP), PARAMETER :: xij(1, 2)=RESHAPE([-1,1], [nsd, nns])
    ! spatial nodal coordinates
    REAL(DFP), ALLOCATABLE :: xija(:, :, :), mat(:,:)
    ! spatial-temporal nodal coordinates
    REAL(DFP), parameter :: c(1,2) = reshape([1.0,1.0],[1,2])
    type(FEVariable_) :: cvar

!!! note "" First, we initiate a [[ReferenceLine_]] element for time domain. Note that nsd should be 1 when making reference element for time domain. Generate the quadrature points, and initiates an instance of [[ElemshapeData_]].

    refelemForTime= ReferenceLine(nsd=1)
    CALL Initiate(obj=quadFortime, &
		& refelem=refelemForTime,&
		& order=orderForTime, &
      	& quadratureType="GaussLegendre" )
    CALL Initiate( &
    	& obj=time_elemsd, &
	  	& quad=quadForTime, &
		& refelem=refelemForTime, &
      	& ContinuityType=typeH1,&
		& InterpolType=TypeLagrangeInterpolation)
    CALL Set(obj=time_elemsd, &
		& val=tiJ, N=time_elemsd%N, &
        & dNdXi=time_elemsd%dNdXi)

!!! note "" Initiate [[STElemshapeData_]].

    CALL Initiate(obj=test, elemsd=time_elemsd)

!!! note "" Generating shape functions for space-elements. Here, we are selecting a triangular element

    refelemForSpace = ReferenceLine(nsd=nsd)
    CALL Initiate(obj=quadForSpace, &
		& refelem=refelemForSpace, &
		& order=orderForSpace, &
		& quadratureType='GaussLegendre')

    DO ii = 1, SIZE(test)
      CALL Initiate( obj=test(ii), &
	  	& quad=quadForSpace, &
		& refelem=refelemForSpace, &
        & ContinuityType=typeH1, &
		& InterpolType=TypeLagrangeInterpolation)
    END DO

!!! note "" Setting the remaining DATA in obj. Here, xija are the space-time nodal coordinates.

	CALL Reallocate(xija, nsd, nns, nnt)
    DO ii = 1, nnt; xija(:, :, ii) = xij; END DO
    DO ii = 1, SIZE(test)
        CALL Set(obj=test(ii), &
            & val=xija, &
			& N=test(ii)%N, &
            & dNdXi=test(ii)%dNdXi, &
            & T=test(ii)%T)
    END DO

!!! note "" Let us now create the space-time convective matrix.

    cvar = NodalVariable(c, typeFEVariableVector, typeFEVariableSpace)

    mat=ConvectiveMatrix(test=test, trial=test, term1=del_none, &
        & term2=del_x, c=cvar)
    CALL Display(mat, "mat:")

??? example "Results"

                mat:                  
----------------------------------------
-0.333333  0.333333  -0.166667  0.166667
-0.333333  0.333333  -0.166667  0.166667
-0.166667  0.166667  -0.333333  0.333333
-0.166667  0.166667  -0.333333  0.333333

    mat=ConvectiveMatrix(test=test, trial=test, term1=del_x, &
        & term2=del_none, c=cvar)
    CALL Display(mat, "mat:")

??? example "Results"

                mat:                   
------------------------------------------
-0.333333  -0.333333  -0.166667  -0.166667
0.333333   0.333333   0.166667   0.166667
-0.166667  -0.166667  -0.333333  -0.333333
0.166667   0.166667   0.333333   0.333333

!!! settings "Cleanup"

END PROGRAM main