Wave tank 3c:
30m by 30m,
Sloping bottom from depth -2.5m at wavemaker to depth 0.5m at x=30.
Initial shoreline at x = 25.
Wavemaker sets velocity at left boundary to:
    u(0,y,t) = 0.2*sin(4*t1) + 0.2*sin(4*t2)
where
    t1 = max(t - .05*(30-y), 0),
    t2 = max(t - .05*y, 0).
Computed on 150x150 grid Some frames: