amun-code/src/evolution.F90

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!!*****************************************************************************
!!
!! module: evolution - handling the time evolution of the block structure
!!
!! Copyright (C) 2008 Grzegorz Kowal <kowal@astro.wisc.edu>
!!
!!*****************************************************************************
!!
!! This file is part of Godunov-AMR.
!!
!! Godunov-AMR is free software; you can redistribute it and/or modify
!! it under the terms of the GNU General Public License as published by
!! the Free Software Foundation; either version 3 of the License, or
!! (at your option) any later version.
!!
!! Godunov-AMR is distributed in the hope that it will be useful,
!! but WITHOUT ANY WARRANTY; without even the implied warranty of
!! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
!! GNU General Public License for more details.
!!
!! You should have received a copy of the GNU General Public License
!! along with this program. If not, see <http://www.gnu.org/licenses/>.
!!
!!*****************************************************************************
!!
!
module evolution
implicit none
integer, save :: n
real , save :: t, dt, dtn
contains
!
!===============================================================================
!
! evolve: subroutine sweeps over all leaf blocks and performs one step time
! evolution for each according to the selected integration scheme
!
!===============================================================================
!
subroutine evolve
use blocks, only : block, plist
use mesh , only : dx_min
use scheme, only : maxspeed
implicit none
! local variables
!
type(block), pointer :: pblock
real :: cmax, cm
!
!-------------------------------------------------------------------------------
!
! iterate over all blocks and perform one step of time evolution
!
pblock => plist
do while (associated(pblock))
! check if this block is a leaf
!
#ifdef RK2
if (pblock%leaf .eq. 'T') &
call evolve_rk2(pblock)
#endif /* RK2 */
! assign pointer to the next block
!
pblock => pblock%next
end do
! TODO: boundary conditions
!
! reset maximum speed
!
cmax = 1.0e-8
! iterate over all blocks in order to find the maximum speed
!
pblock => plist
do while (associated(pblock))
! check if this block is a leaf
!
if (pblock%leaf .eq. 'T') &
cm = maxspeed(pblock%u)
! compare global and local maximum speeds
!
cmax = max(cmax, cm)
! assign pointer to the next block
!
pblock => pblock%next
end do
! get maximum time step
!
dtn = dx_min / max(cmax, 1.e-8)
!-------------------------------------------------------------------------------
!
end subroutine evolve
#ifdef RK2
!
!===============================================================================
!
! evolve_rk2: subroutine evolves the current block using RK2 integration
!
!===============================================================================
!
subroutine evolve_rk2(pblock)
use blocks, only : block, nvars
use config, only : igrids, jgrids, kgrids
use mesh , only : adxi, adyi, adzi
use scheme, only : update
implicit none
! input arguments
!
type(block), pointer, intent(inout) :: pblock
! local variables
!
integer :: q, i, j, k
real :: dxi, dyi, dzi
! local arrays
!
real, dimension(nvars,igrids,jgrids,kgrids) :: u1, du
!
!-------------------------------------------------------------------------------
!
! prepare dxi, dyi, and dzi
!
dxi = adxi(pblock%level)
dyi = adyi(pblock%level)
dzi = adzi(pblock%level)
! 1st step of integration
!
call update(pblock%u, du, dxi, dyi, dzi)
! update solution
!
do k = 1, kgrids
do j = 1, jgrids
do i = 1, igrids
do q = 1, nvars
u1(q,i,j,k) = pblock%u(q,i,j,k) + dt*du(q,i,j,k)
end do
end do
end do
end do
! 2nd step of integration
!
call update(u1, du, dxi, dyi, dzi)
! update solution
!
do k = 1, kgrids
do j = 1, jgrids
do i = 1, igrids
do q = 1, nvars
pblock%u(q,i,j,k) = 0.5 * (pblock%u(q,i,j,k) + u1(q,i,j,k) &
+ dt*du(q,i,j,k))
end do
end do
end do
end do
!-------------------------------------------------------------------------------
!
end subroutine evolve_rk2
#endif /* RK2 */
!===============================================================================
!
end module