c c c c ================================================================== subroutine rpn3acv(ixyz,maxm,meqn,mwaves,mbc,mx,ql,qr, & maux,auxl,auxr,wave,s,amdq,apdq) c ================================================================== c c # Riemann solver for the acoustics equations in 3d, with varying c # material properties. c c # auxl(i,1) holds impedance rho, c # auxl(i,2) holds sound speed c, c c # Note that although there are 4 eigenvectors, two eigenvalues are c # always zero and so we only need to compute 2 waves. c c # Solve Riemann problems along one slice of data. c # This data is along a slice in the x-direction if ixyz=1 c # the y-direction if ixyz=2. c # the z-direction if ixyz=3. c c # On input, ql contains the state vector at the left edge of each cell c # qr contains the state vector at the right edge of each cell c c # Note that the i'th Riemann problem has left state qr(i-1,:) c # and right state ql(i,:) c # From the basic clawpack routines, this routine is called with ql = qr c c implicit real*8(a-h,o-z) dimension wave(1-mbc:maxm+mbc, meqn, mwaves) dimension s(1-mbc:maxm+mbc, mwaves) dimension ql(1-mbc:maxm+mbc, meqn) dimension qr(1-mbc:maxm+mbc, meqn) dimension amdq(1-mbc:maxm+mbc, meqn) dimension apdq(1-mbc:maxm+mbc, meqn) dimension auxl(1-mbc:maxm+mbc, maux, 3) dimension auxr(1-mbc:maxm+mbc, maux, 3) c c local arrays c ------------ dimension delta(3) c c c # set mu to point to the component of the system that corresponds c # to velocity in the direction of this slice, mv to the orthogonal c # velocity. c c if (ixyz.eq.1) then mu = 2 mv = 3 mw = 4 else if (ixyz.eq.2) then mu = 3 mv = 4 mw = 2 else if (ixyz.eq.3) then mu = 4 mv = 2 mw = 3 endif c c # split the jump in q at each interface into waves c # The jump is split into a leftgoing wave traveling at speed -c c # relative to the material properties to the left of the interface, c # and a rightgoing wave traveling at speed +c c # relative to the material properties to the right of the interface, c c # find a1 and a2, the coefficients of the 2 eigenvectors: do 20 i = 2-mbc, mx+mbc delta(1) = ql(i,1) - qr(i-1,1) delta(2) = ql(i,mu) - qr(i-1,mu) c # impedances: zi = auxl(i,1,2)*auxl(i,2,2) zim = auxl(i-1,1,2)*auxl(i-1,2,2) a1 = (-delta(1) + zi*delta(2)) / (zim + zi) a2 = (delta(1) + zim*delta(2)) / (zim + zi) c c # Compute the waves. c wave(i,1,1) = -a1*zim wave(i,mu,1) = a1 wave(i,mv,1) = 0.d0 wave(i,mw,1) = 0.d0 s(i,1) = -auxl(i-1,2,2) c wave(i,1,2) = a2*zi wave(i,mu,2) = a2 wave(i,mv,2) = 0.d0 wave(i,mw,2) = 0.d0 s(i,2) = auxl(i,2,2) c 20 continue c c c # compute the leftgoing and rightgoing flux differences: c # Note s(i,1) < 0 and s(i,2) > 0. c do 220 m=1,meqn do 220 i = 2-mbc, mx+mbc amdq(i,m) = s(i,1)*wave(i,m,1) apdq(i,m) = s(i,2)*wave(i,m,2) 220 continue c c return end