Wave patterns generated by an axisymmetric obstacle in a two-layer flow

Laurent Lacaze (1) , Alexandre Paci (2) , Emmanuel Cid (1) , Sébastien Cazin (1) , Olivier Eiff (1) , J. G. Esler (3) , E. R. Johnson (3)

1 IMFT - Institut de mécanique des fluides de Toulouse
2 CNRM - Centre national de recherches météorologiques
3 UCL - University College of London [London]

Gravity waves generated by a moving obstacle in a two-layer stratified fluid are investigated. The experimental configuration is three-dimensional with an axisymmetric obstacle which is towed in one of the two layers. The experimental method used in the present study is based on a stereoscopic technique allowing the 3D reconstruction of the interface between the two layers. Investigation into the wave pattern as a function of the Froude number, Fr, based on the relative density of the fluid layers and the velocity of the towed obstacle is presented. Specific attention is paid to the transcritical regime for which Fr is close to one. Potential energy trapped in the wave field patterns is also extracted from the experimental results and is analyzed as a function of both the Froude number, Fr, and the transcritical similarity parameter Gamma. In particular, a remarkable increase in the potential energy around Fr = 1 is observed and a scaling allowing to assemble data resulting from different experimental parameters is proposed.

Mots clés: Stratifed flows; Gravity Waves; Wakes

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Laurent Lacaze, Alexandre Paci, Emmanuel Cid, Sébastien Cazin, Olivier Eiff, et al.. Wave patterns generated by an axisymmetric obstacle in a two-layer flow. Experiments in Fluids, 2013, vol. 54, pp. 1-10. ⟨10.1007/s00348-013-1618-z⟩. ⟨hal-00958121⟩