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stepgrid.f.html |
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Source file: stepgrid.f
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Directory: /home/rjl/git/rjleveque/clawpack-4.x/amrclaw/2d/lib
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Converted: Tue Jul 26 2011 at 12:59:08
using clawcode2html
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This documentation file will
not reflect any later changes in the source file.
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c
c -------------------------------------------------------------
c
subroutine stepgrid(q,fm,fp,gm,gp,mitot,mjtot,mbc,dt,dtnew,dx,dy,
& nvar,xlow,ylow,time,mptr,maux,aux)
c
c
c ::::::::::::::::::: STEPGRID ::::::::::::::::::::::::::::::::::::
c take a time step on a single grid. overwrite solution array q.
c A modified version of the clawpack routine step2 is used.
c
c return fluxes in fm,fp and gm,gp.
c patch has room for ghost cells (mbc of them) around the grid.
c everything is the enlarged size (mitot by mjtot).
c
c mbc = number of ghost cells (= lwidth)
c mptr = grid number (for debugging)
c xlow,ylow = lower left corner of enlarged grid (including ghost cells).
c dt = incoming time step
c dx,dy = mesh widths for this grid
c dtnew = return suggested new time step for this grid's soln.
c
c :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
implicit double precision (a-h,o-z)
external rpn2,rpt2
include "call.i"
common /comxyt/ dtcom,dxcom,dycom,tcom,icom,jcom
parameter (msize=max1d+4)
parameter (mwork=msize*(maxvar*maxvar + 13*maxvar + 3*maxaux +2))
dimension q(mitot,mjtot,nvar)
dimension fp(mitot,mjtot,nvar),gp(mitot,mjtot,nvar)
dimension fm(mitot,mjtot,nvar),gm(mitot,mjtot,nvar)
dimension aux(mitot,mjtot,maux)
dimension work(mwork)
logical debug, dump
data debug/.false./, dump/.false./
c
c # set tcom = time. This is in the common block comxyt that could
c # be included in the Riemann solver, for example, if t is explicitly
c # needed there.
tcom = time
if (dump) then
do i = 1, mitot
do j = 1, mjtot
write(outunit,545) i,j,(q(i,j,ivar),ivar=1,nvar)
545 format(2i4,4e15.7)
end do
end do
endif
c
meqn = nvar
mx = mitot - 2*mbc
my = mjtot - 2*mbc
maxm = max(mx,my) !# size for 1d scratch array
mbig = maxm
xlowmbc = xlow + mbc*dx
ylowmbc = ylow + mbc*dy
c # method(2:7) and mthlim
c # are set in the amr2ez file (read by amr)
c
method(1) = 0
c
c
c # fluxes initialized in step2
c
mwork0 = (maxm+2*mbc)*(12*meqn + mwaves + meqn*mwaves + 2)
c
if (mwork .lt. mwork0) then
write(outunit,*) 'CLAW2 ERROR... mwork must be increased to ',
& mwork0
write(* ,*) 'CLAW2 ERROR... mwork must be increased to ',
& mwork0
stop
endif
c
c # partition work array into pieces needed for local storage in
c # step2 routine. Find starting index of each piece:
c
i0faddm = 1
i0faddp = i0faddm + (maxm+2*mbc)*meqn
i0gaddm = i0faddp + (maxm+2*mbc)*meqn
i0gaddp = i0gaddm + 2*(maxm+2*mbc)*meqn
i0q1d = i0gaddp + 2*(maxm+2*mbc)*meqn
i0dtdx1 = i0q1d + (maxm+2*mbc)*meqn
i0dtdy1 = i0dtdx1 + (maxm+2*mbc)
i0aux1 = i0dtdy1 + (maxm+2*mbc)
i0aux2 = i0aux1 + (maxm+2*mbc)*maux
i0aux3 = i0aux2 + (maxm+2*mbc)*maux
c
c
i0next = i0aux3 + (maxm+2*mbc)*maux !# next free space
mused = i0next - 1 !# space already used
mwork1 = mwork - mused !# remaining space (passed to step2)
c
c
call b4step2(mx,my,mbc,mx,my,nvar,q,
& xlowmbc,ylowmbc,dx,dy,time,dt,maux,aux)
c
c
c # take one step on the conservation law:
c
call step2(mbig,mx,my,nvar,maux,
& mbc,mx,my,
& q,aux,dx,dy,dt,cflgrid,
& fm,fp,gm,gp,
& work(i0faddm),work(i0faddp),
& work(i0gaddm),work(i0gaddp),
& work(i0q1d),work(i0dtdx1),work(i0dtdy1),
& work(i0aux1),work(i0aux2),work(i0aux3),
& work(i0next),mwork1,rpn2,rpt2)
c
c
write(outunit,1001) mptr, node(nestlevel,mptr),cflgrid
1001 format(' Courant # of grid', i4,
& ' on level', i3, ' is ', e10.3)
c
cflmax = dmax1(cflmax,cflgrid)
cfl_level = dmax1(cfl_level,cflgrid)
c
c # update q
dtdx = dt/dx
dtdy = dt/dy
do 50 m=1,nvar
do 50 i=mbc+1,mitot-mbc
do 50 j=mbc+1,mjtot-mbc
if (mcapa.eq.0) then
c
c # no capa array. Standard flux differencing:
q(i,j,m) = q(i,j,m)
& - dtdx * (fm(i+1,j,m) - fp(i,j,m))
& - dtdy * (gm(i,j+1,m) - gp(i,j,m))
else
c # with capa array.
q(i,j,m) = q(i,j,m)
& - (dtdx * (fm(i+1,j,m) - fp(i,j,m))
& + dtdy * (gm(i,j+1,m) - gp(i,j,m))) / aux(i,j,mcapa)
endif
50 continue
c
c
if (method(5).eq.1) then
c # with source term: use Godunov splitting
call src2(mx,my,nvar,mbc,mx,my,xlowmbc,ylowmbc,dx,dy,
& q,maux,aux,time,dt)
endif
c
c
c
c # output fluxes for debugging purposes:
if (debug) then
write(dbugunit,*)" fluxes for grid ",mptr
do 830 i = mbc+1, mitot-1
do 830 j = mbc+1, mjtot-1
write(dbugunit,831) i,j,fm(i,j,1),fp(i,j,1),
. gm(i,j,1),gp(i,j,1)
do 830 m = 2, meqn
write(dbugunit,832) fm(i,j,m),fp(i,j,m),
. gm(i,j,m),gp(i,j,m)
831 format(2i4,4d16.6)
832 format(8x,4d16.6)
830 continue
endif
c
c
c For variable time stepping, use max speed seen on this grid to
c choose the allowable new time step dtnew. This will later be
c compared to values seen on other grids.
c
if (cflgrid .gt. 0.d0) then
dtnew = dt*cfl/cflgrid
else
c # velocities are all zero on this grid so there's no
c # time step restriction coming from this grid.
dtnew = rinfinity
endif
c # give a warning if Courant number too large...
c
if (cflgrid .gt. cflv1) then
write(*,810) cflgrid
write(outunit,810) cflgrid, cflv1
810 format('*** WARNING *** Courant number =', d12.4,
& ' is larger than input cfl_max = ', d12.4)
endif
c
return
end