(1973) n°3 - Royal Academy for Overseas Sciences

— 592 —
Another approach in the study of the flow of inhomogeneous
fluids with a continuous density stratification, was confined
to quasi-horizontal motions. Lu sc z y n sk i (19) introduced the
concept of point-water head, fresh-water head and environmental
water-head. He used wells as manometers to record these
hydraulic heads in terms of any of which Darcy’s law can be
formulated. This concept has proved increasingly useful in monitoring
in situ the flow of salinity-stratified groundwaters.
The study of quasi-horizontal motions of continuously stratified
fluids was further extended by Yih (37). Assuming that
the flow is confined in the vertical direction in a homogeneous
layer of depth H, he derived the equation for the stream
function for a two-dimensional flow in which streamlines are
isopicnic lines. Even if the diffusivity term, kV2p, is included
in the equation for the conservation of salt (17), there exists
an exact solution for the flow to a line-sink at the upper boundary
provided that the medium extends horizontally to infinity.
Even if the medium is infinite in the vertical direction as well,
L ist (16) found out an exact solution for the flow of a density-stratified
fluid towards a line-sink. The solution, sketched
in figure 5, confirmed the hypothesis that the sink withdraws
fluid from a relatively thin layer at the level of the sink. The
density distribution, p