Initialisation 
Dipole:      velocity: U = 2; maximum initial vorticity 22.1
             radius: a = 1  
             angle of dipole axis with X-axis: 0 degrees
             position: centre of the domain (0,0)
Computation: domain: X = (-3, ..., 3), Y = (-3, ..., 3)
             no. of grid points from wall to wall: (129, 129)
             boundary conditions: no-slip along all walls
             standard Arakawa scheme used
             no rotation effects included
             no bottom topography
             viscosity: nu = 10^-3 (i.e. Re=1000 at T=0)
             time step: dt = 0.005
             final time: T = 4.0 (graphs) and 7.5 (movie)
Tracers:     graphs: along vorticity contours (i.e. along 
                     streamlines) of the Lamb dipole at 
                     vorticity level: 0.1; and single 
                     tracers at each extremum
             movie:  none

Notes
- The tracer lines are not always smooth. The reason for 
  this is that the representation of the lines by points 
  is not always accurate enough. But since these tracers 
  only passively follow the flow, this has no effect on 
  the computations. It needs repair, though.
- The graphs are made on half resolution, i.e. only
  1 in every 2 points.

<=== Lamb dipole in a domain with no-slip walls

 
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created: 12 December 1995
last modified: 26 May 2001