Observations of stratified flow past Three‐dimensional barriers

Experiments on stratified flow at large Reynolds numbers over barriers with gaps, towed along the bottom of a long tank, are described. The primary purpose of the observations was to determine the circumstances under which fluid flows over the barrier or is deflected horizontally around the barrier through the gap. A range of gap widths (including zero) was used, and the barrier had ‘Witch of Agnesi’ profile with height ∼ half width. For the two‐dimensional barrier (i.e., zero gap), blocked fluid was observed upstream if F = U/Nh < 0.5. For the same barrier with a gap, if F < 0.5, all the fluid incident below a certain height zs (<h) flowed around the barrier through the gap; above this height the fluid flowed over the barrier in nearly two‐dimensional fashion. The parameter zs is a function of both F and gap width. For F > 0.5 all (or almost all) of the fluid incident on the barrier flowed over it, and the motion was predominantly two‐dimensional in the vertical plane.