Laboratory Study of Rotating, Stratified, Oscillatory Flow over a Seamount

Abstract Pure oscillatory flow of a rotating, linearly stratified fluid in the vicinity of an isolated topography of revolution is considered in the laboratory. The pertinent dimensionless parameters governing the motion are the Rossby (Ro), temporal Rossby (Rot), Burger (S), and Ekman (E) numbers and geometrical length-scale ratios. Experiments are considered for fixed S, E and geometry and ranges of Ro and Rot given by 0.003 ≤ Ro ≤ 0.03 and 0.2 ≤ Rot ≤ 2.4. A Rot against Ro regime diagram is developed, which includes the following flow classifications: (i) attached flow (AF), (ii) tidal oscillation loops (TOL), (iii) trapped waves-anticyclonic/cyclonic residual current (WAC), (iv) trapped waves-anticyclonic residual current (WA), (v) attached eddies (AE), and (vi) vortex shedding (VS). For all flow regimes a rectified mean anticyclonic motion is observed in the vicinity of the topography. For superinertial frequencies (i.e., Rot > 1), a resonance phenomenon enhances the streamwise speed near the obstacl...