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We present an experimental study on the propagation speed of gravity currents at moderate values of a gravity Reynolds number. The propagation speed is analysed for two cases: gravity currents propagating along a rigid boundary and intrusive gravity currents. For the first case, a semi-empirical formula for the front propagation speed derived from simple energy arguments is shown to capture well the effect of flow deceleration because of viscous dissipation. In the second case, the propagation speed is shown to agree with the one predicted for energy-conserving virtually inviscid flows (Shin, Dalziel & Linden, JFM. V. 521, 2004), which implies that the losses due to vorticity generation and mixing at the liquid-liquid interface play only a minor role on the total balance of energy. We also present an experimental study of forces induced by gravity currents on submerged obstacles represented by fixed horizontal cylinders with circular and rectangular cross-sections. |
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