c c c ===================================================== subroutine bc1(maxmx,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(1-mbc:maxmx+mbc, meqn) dimension aux(1-mbc:maxmx+mbc, *) dimension mthbc(2) common /comrp/ 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(xlower,t) = g(t) t0 = t + dx/(2.d0*u) q(0,1) = 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 115 m=1,meqn do 115 ibc=1,mbc q(1-ibc,m) = q(1,m) 115 continue go to 199 120 continue c # periodic: do 125 m=1,meqn do 125 ibc=1,mbc q(1-ibc,m) = q(mx+1-ibc,m) 125 continue go to 199 130 continue c # solid wall (assumes 2'nd component is velocity or momentum in x): do 135 m=1,meqn do 135 ibc=1,mbc q(1-ibc,m) = q(ibc,m) 135 continue c # negate the normal velocity: do 136 ibc=1,mbc q(1-ibc,2) = -q(ibc,2) 136 continue 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 215 m=1,meqn do 215 ibc=1,mbc q(mx+ibc,m) = q(mx,m) 215 continue go to 299 220 continue c # periodic: do 225 m=1,meqn do 225 ibc=1,mbc q(mx+ibc,m) = q(ibc,m) 225 continue go to 299 230 continue c # solid wall (assumes 2'nd component is velocity or momentum in x): do 235 m=1,meqn do 235 ibc=1,mbc q(mx+ibc,m) = q(mx+1-ibc,m) 235 continue do 236 ibc=1,mbc q(mx+ibc,2) = -q(mx+1-ibc,2) 236 continue go to 299 299 continue c return end