SELF_advection_diffusion_2d_t.f90 Source File


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module self_advection_diffusion_2d_t

  use self_dgmodel2d
  use self_mesh

  implicit none

  type,extends(dgmodel2d) :: advection_diffusion_2d_t
    real(prec) :: nu ! diffusion coefficient
    real(prec) :: u ! constant x-component of velocity
    real(prec) :: v ! constant y-component of velocity

  contains
    procedure :: riemannflux2d => riemannflux2d_advection_diffusion_2d_t
    procedure :: flux2d => flux2d_advection_diffusion_2d_t
    procedure :: entropy_func => entropy_func_advection_diffusion_2d_t

  endtype advection_diffusion_2d_t

contains

  pure function entropy_func_advection_diffusion_2d_t(this,s) result(e)
    class(advection_diffusion_2d_t),intent(in) :: this
    real(prec),intent(in) :: s(1:this%solution%nvar)
    real(prec) :: e
    ! Local
    integer :: ivar

    e = 0.0_prec
    do ivar = 1,this%solution%nvar
      e = e+0.5_prec*s(ivar)*s(ivar)
    enddo

  endfunction entropy_func_advection_diffusion_2d_t

  pure function flux2d_advection_diffusion_2d_t(this,s,dsdx) result(flux)
    class(advection_diffusion_2d_t),intent(in) :: this
    real(prec),intent(in) :: s(1:this%solution%nvar)
    real(prec),intent(in) :: dsdx(1:this%solution%nvar,1:2)
    real(prec) :: flux(1:this%solution%nvar,1:2)
    ! Local
    integer :: ivar

    do ivar = 1,this%solution%nvar
      flux(ivar,1) = this%u*s(ivar)-this%nu*dsdx(ivar,1) ! advective flux + diffusive flux
      flux(ivar,2) = this%v*s(ivar)-this%nu*dsdx(ivar,2) ! advective flux + diffusive flux
    enddo

  endfunction flux2d_advection_diffusion_2d_t

  pure function riemannflux2d_advection_diffusion_2d_t(this,sL,sR,dsdx,nhat) result(flux)
    class(advection_diffusion_2d_t),intent(in) :: this
    real(prec),intent(in) :: sL(1:this%nvar)
    real(prec),intent(in) :: sR(1:this%nvar)
    real(prec),intent(in) :: dsdx(1:this%nvar,1:2)
    real(prec),intent(in) :: nhat(1:2)
    real(prec) :: flux(1:this%nvar)
    ! Local
    integer :: ivar
    real(prec) :: un,dsdn

    un = this%u*nhat(1)+this%v*nhat(2)

    do ivar = 1,this%nvar
      dsdn = dsdx(ivar,1)*nhat(1)+dsdx(ivar,2)*nhat(2)
      flux(ivar) = 0.5_prec*( &
                   (sL(ivar)+sR(ivar))+abs(un)*(sL(ivar)-sR(ivar)))- & ! advective flux
                   this%nu*dsdn
    enddo

  endfunction riemannflux2d_advection_diffusion_2d_t

endmodule self_advection_diffusion_2d_t