bc1.f.html | |
Source file: bc1.f | |
Directory: /Users/rjl/clawpack_src/clawpack_master/apps/fvmbook/chap7/advinflow | |
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c c c ===================================================== subroutine bc1(meqn,mbc,mx,xlower,dx,q,maux,aux,t,dt,mthbc) c ===================================================== c c # Standard boundary condition choices for claw2 c c # At each boundary k = 1 (left), 2 (right): c # mthbc(k) = 0 for user-supplied BC's (must be inserted!) c # = 1 for zero-order extrapolation c # = 2 for periodic boundary coniditions c # = 3 for solid walls, assuming this can be implemented c # by reflecting the data about the boundary and then c # negating the 2'nd component of q. c ------------------------------------------------ c c # Extend the data from the computational region c # i = 1, 2, ..., mx2 c # to the virtual cells outside the region, with c # i = 1-ibc and i = mx+ibc for ibc=1,...,mbc c implicit double precision (a-h,o-z) dimension q(meqn,1-mbc:mx+mbc) dimension aux(maux,1-mbc:mx+mbc) dimension mthbc(2) common /cparam/ u c c c------------------------------------------------------- c # left boundary: c------------------------------------------------------- go to (100,110,120,130) mthbc(1)+1 c 100 continue c # user-specified boundary conditions go here in place of error output c # for inflow, q(t,xlower) = g(t) t0 = t + dx/(2.d0*u) q(1,0) = g(t0) tm1 = t + 3.d0*dx/(2.d0*u) q(1,-1) = g(tm1) go to 199 c 110 continue c # zero-order extrapolation: do m=1,meqn do ibc=1,mbc q(m,1-ibc) = q(m,1) enddo enddo go to 199 120 continue c # periodic: do m=1,meqn do ibc=1,mbc q(m,1-ibc) = q(m,mx+1-ibc) enddo enddo go to 199 130 continue c # solid wall (assumes 2'nd component is velocity or momentum in x): do m=1,meqn do ibc=1,mbc q(m,1-ibc) = q(m,ibc) enddo enddo c # negate the normal velocity: do ibc=1,mbc q(2,1-ibc) = -q(2,ibc) enddo go to 199 199 continue c c------------------------------------------------------- c # right boundary: c------------------------------------------------------- go to (200,210,220,230) mthbc(2)+1 c 200 continue c # user-specified boundary conditions go here in place of error output write(6,*) '*** ERROR *** mthbc(2)=0 and no BCs specified in bc1' stop go to 299 210 continue c # zero-order extrapolation: do m=1,meqn do ibc=1,mbc q(m,mx+ibc) = q(m,mx) enddo enddo go to 299 220 continue c # periodic: do m=1,meqn do ibc=1,mbc q(m,mx+ibc) = q(m,ibc) enddo enddo go to 299 230 continue c # solid wall (assumes 2'nd component is velocity or momentum in x): do m=1,meqn do ibc=1,mbc q(m,mx+ibc) = q(m,mx+1-ibc) enddo enddo do ibc=1,mbc q(2,mx+ibc) = -q(2,mx+1-ibc) enddo go to 299 299 continue c return end