In the present study the flow through and around a parallel walled cha
nnel with various obstruction geometries placed at the channel entry i
s investigated. The flow inside the channel is found to be either stag
nant, reverse, or in the forward direction depending upon the position
of the obstruction. Experiments were carried out with various obstruc
tion geometries like square, triangular, circular and semi-circular to
study the effect of the shape of the geometry on the reverse flow phe
nomenon. Of the four, the triangular geometry gave the maximum reverse
flow. The square and the semi-circular gave almost the same as the fl
at plate. The maximum forward flow also depends upon the shape of the
obstruction geometry. To study the effect of the afterbody length the
rectangular shape was chosen and models of different afterbody lengths
were investigated. It is seen that the shorter afterbody lengths give
a higher reverse flow. The maximum forward flow velocity however is h
igher for larger afterbody lengths.