!-----------------------------------------------------------------------
! Physical boundary conditions for 2d Euler equations.
! Reflecting walls at all sides.
! Interface:
! mx,my := shape of grid function
!
! u(,) := grid function
!
! lb(2) := lower bound for grid
! ub(2) := upper bound for grid
! lbbnd(2) := lower bound for boundary region
! ubnd(2) := upper bound for boundary region
! shapebnd(2) := shape of boundary region
! xc(2) := lower left corner of grid
! dx(2) := grid spacing
! dir := at which side of the grid is the boundary?
! bnd(,2,2) := lower left and upper right corner of global grid and
! of mb-1 internal boundary regions
!
! The implementation is quite general, because
! - a boundary region can have a width of 1 or 2 ghost cells.
! - corners of a grid might be part of two boundaries and it is NOT
! guaranteed that ALL cells of a particular corner region are
! contained in both boundaries.
!
! Copyright (C) 2002 Ralf Deiterding
! Brandenburgische Universitaet Cottbus
!
! Copyright (C) 2003-2007 California Institute of Technology
! Ralf Deiterding, ralf@cacr.caltech.edu
!
!-----------------------------------------------------------------------
subroutine physbd(u,mx,my,lb,ub,lbbnd,ubbnd,shapebnd,
& xc,dx,dir,bnd,mb,time,meqn)
implicit none
integer mx, my, meqn, mb, dir
integer lb(2), ub(2), lbbnd(2), ubbnd(2), shapebnd(2)
double precision u(meqn, mx, my), xc(2), dx(2), bnd(mb,2,2), time
! Local variables
integer i, j, imin, imax, jmin, jmax, m, isym, jsym
integer stride, getindx
integer isx(4), isy(4)
c
data isx /1,-1,1,1/
data isy /1,1,-1,1/
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
! See definition of member-function extents() in BBox.h
! for calculation of stride
stride = (ub(1) - lb(1))/(mx-1)
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
! Find working domain
imin = getindx(max(lbbnd(1), lb(1)), lb(1), stride)
imax = getindx(min(ubbnd(1), ub(1)), lb(1), stride)
jmin = getindx(max(lbbnd(2), lb(2)), lb(2), stride)
jmax = getindx(min(ubbnd(2), ub(2)), lb(2), stride)
go to (100,200,300,400) dir+1
! Left Side --- Reflection
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
100 continue
do 110 i = imax, imin, -1
if (xc(1)+(i-0.5d0)*dx(1).lt.bnd(1,1,1)) then
isym = 2*imax+1-i
do 120 j = jmin, jmax
do 120 m = 1, meqn
u(m,i,j) = u(m,isym,j)*isx(m)
120 continue
endif
110 continue
return
! Right Side --- Reflection
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
200 continue
do 210 i = imin, imax
if (xc(1)+(i-0.5d0)*dx(1).gt.bnd(1,2,1)) then
isym = 2*imin-1-i
do 220 j = jmin, jmax
do 220 m = 1, meqn
u(m,i,j) = u(m,isym,j)*isx(m)
220 continue
endif
210 continue
return
! Bottom Side --- Reflection
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
300 continue
do 310 j = jmax, jmin, -1
if (xc(2)+(j-0.5d0)*dx(2).lt.bnd(1,1,2)) then
jsym = 2*jmax+1-j
do 320 i = imin, imax
do 320 m = 1, meqn
u(m,i,j) = u(m,i,jsym)*isy(m)
320 continue
endif
310 continue
return
! Top Side --- Reflection
!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
400 continue
do 410 j = jmin, jmax
if (xc(2)+(j-0.5d0)*dx(2).gt.bnd(1,2,2)) then
jsym = 2*jmin-1-j
do 420 i = imin, imax
do 420 m = 1, meqn
u(m,i,j) = u(m,i,jsym)*isy(m)
420 continue
endif
410 continue
return
end