qinit.f.html CLAWPACK  
 Source file:   qinit.f
 Directory:   /Users/rjl/clawpack_src/clawpack_master/classic/examples/acoustics_2d_radial
 Converted:   Mon Feb 19 2024 at 17:58:23   using clawcode2html
 This documentation file will not reflect any later changes in the source file. 

 

c
c
c
c     =====================================================
       subroutine qinit(meqn,mbc,mx,my,xlower,ylower,
     &                   dx,dy,q,maux,aux)
c     =====================================================
c
c     # Set initial conditions for q.
c     # Acoustics with smooth radially symmetric profile to test accuracy
c
       implicit double precision (a-h,o-z)
       dimension q(meqn, 1-mbc:mx+mbc, 1-mbc:my+mbc)
c
       pi = 4.d0*datan(1.d0)
       width = 0.2d0

       do 20 i=1,mx
          xcell = xlower + (i-0.5d0)*dx
          do 20 j=1,my
             ycell = ylower + (j-0.5d0)*dy
             r = dsqrt(xcell**2 + ycell**2)

             if (dabs(r-0.5d0) .le. width) then
                 pressure = 1.d0 + dcos(pi*(r - 0.5d0)/width)
               else
                 pressure = 0.d0
               endif
             q(1,i,j) = pressure
             q(2,i,j) = 0.d0
             q(3,i,j) = 0.d0
  20         continue
       return
       end