c c c ===================================================== subroutine rpt2(ixy,maxm,meqn,mwaves,mbc,mx, & ql,qr,aux1,aux2,aux3, & ilr,asdq,bmasdq,bpasdq) c ===================================================== implicit double precision (a-h,o-z) c c # Riemann solver in the transverse direction for the shallow water c equations . c # Split asdq (= A^* \Delta q, where * = + or -) c # into down-going flux difference bmasdq (= B^- A^* \Delta q) c # and up-going flux difference bpasdq (= B^+ A^* \Delta q) c c # Uses Roe averages and other quantities which were c # computed in rpn2sh and stored in the common block comroe. c dimension ql(1-mbc:maxm+mbc, meqn) dimension qr(1-mbc:maxm+mbc, meqn) dimension asdq(1-mbc:maxm+mbc, meqn) dimension bmasdq(1-mbc:maxm+mbc, meqn) dimension bpasdq(1-mbc:maxm+mbc, meqn) c common /param/ g !# gravitational parameter dimension waveb(3,3),sb(3) parameter (maxm2 = 603) !# assumes at most 600x600 grid with mbc=3 common /comroe/ u(-2:maxm2),v(-2:maxm2),a(-2:maxm2),hl(-2:maxm2), & hr(-2:maxm2) c if (-2.gt.1-mbc .or. maxm2 .lt. maxm+mbc) then write(6,*) 'need to increase maxm2 in rpB' stop endif c if (ixy.eq.1) then mu = 2 mv = 3 else mu = 3 mv = 2 endif c do 20 i = 2-mbc, mx+mbc a1 = (0.50d0/a(i))*((v(i)+a(i))*asdq(i,1)-asdq(i,mv)) a2 = asdq(i,mu) - u(i)*asdq(i,1) a3 = (0.50d0/a(i))*(-(v(i)-a(i))*asdq(i,1)+asdq(i,mv)) c waveb(1,1) = a1 waveb(mu,1) = a1*u(i) waveb(mv,1) = a1*(v(i)-a(i)) sb(1) = v(i) - a(i) c waveb(1,2) = 0.0d0 waveb(mu,2) = a2 waveb(mv,2) = 0.0d0 sb(2) = v(i) c waveb(1,3) = a3 waveb(mu,3) = a3*u(i) waveb(mv,3) = a3*(v(i)+a(i)) sb(3) = v(i) + a(i) c c # compute the flux differences bmasdq and bpasdq c do 10 m=1,meqn bmasdq(i,m) = 0.d0 bpasdq(i,m) = 0.d0 do 10 mw=1,mwaves bmasdq(i,m) = bmasdq(i,m) & + dmin1(sb(mw), 0.d0) * waveb(m,mw) bpasdq(i,m) = bpasdq(i,m) & + dmax1(sb(mw), 0.d0) * waveb(m,mw) 10 continue c 20 continue c return end