Abstract:
Selective withdrawal from stable stratified fluid system is a well known technique of water
quality management. Stratification is caused due to density variation in an incompressible fluid
or entropy variation in compressible fluid. The causes of density variation are primarily
temperature variation with depth and secondarily, by a variable concentration of dissolved or
suspended solid. Selective withdrawal is one, where one can select the strata of the fluid at the
sink level. Hence, the !low is restricted into horizontal layer which enables the water to he
withdrawn in horizontal layers.
Flow from stratified fluid system depends on many parameters like nature of stratification,
thickness of interface, flow-rate, shape of sink, location of sink, rotation etc. l3ut for
characterizing the flow, the above physical parameters are converted into fluid dynamic
parameters as drawdown, Froude numbers (densimetric Froude number, interface Froude
numher and intake Froude number) etc. In the present thesis, sinks were taken capped and
observed that cap size on sink effects percentage of drawdown significantly. Hence, it is also
found that a generalized relationship hetwcen drawdown, Froude numbers and cap dimension
parameter from observed data can be made.
