A series of laboratory experiments have been run with the
apparatus shown on Kincaid's homepage to study the
interaction between plate driven flow beneath ridges
and buoyancy driven flow (plumes). This sequence of
plots shows the fluid in shadowgraph looking down the
spreading axis (left frames) and perpendicular to the
spreading axis (right frames). The frames show the evolution
of a fluid which is heated from below (beneath the spreading
axis) and which is also being driven by diverging surface plates.
Both views show the generation of plumes which rise beneath
the ridge. The plate rate in this case would be considered
intermediate (scaling to about 4 cm/yr in the mantle) and
the resulting flow is transitional between 3-D, plume-dominated
flow (left side of ridge-perpendicular frames) and plate-dominated
flow (e.g., a 2-D sheet of rising fluid beneath the ridge as on the
right side of the ridge-perpendicular frames).
This sequence of ridge-perpendicular frames shows the influence
of plate spreading rate on the morphology of plumes. As spreading
rate increases, plumes are supressed.
This last sequence of frames from experiments with uniform heating of the fluid from below and moving plates shows plumes developing and
being swept to the ridge (or spreading) axis.
Another method for viewing fluid flow patterns in the tank involves
shinning a HeNe laser through a sequence of lenses to produce a
vertical sheet of laser light. The light refracts off of small
metal flakes in the fluid and a time lapes image of this field
maps out fluid flow lines as is shown here.
This work is part of a collaborative effort with Bob Detrick (Woods Hole Oceanographic Institution) and David Sparks (Lamont Doherty Earth Observatory).