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The present work investigates free damped oscillations of an oil drop in water after its release from a capillary tube. Both pure heptane drops and diluted crude oil drops are considered (in the second case the interface is covered by amphiphilic species, natural components of crude oil). Shadowgraph images of the drops are taken by means of a high speed camera and the drop contour is detected by image processing. The axisymmetric drop shape is then decomposed into spherical harmonics, which constitute the eigenmodes of oscillations predicted by the Rayleigh-Lamb theory. Time evolution of each mode is then obtained. The frequency and the damping rate of the principal mode (n=2) are accurately determined and compared with theoretical values for an immobile clean drop oscillating around spherical shape. For pure heptane drops, theoretical value of the frequency agrees well with experiments whereas the damping rate is significantly underestimated by theory. The experimental results clearly show that the different modes are coupled. Energy is thus transfered from mode n=2 to n=3, which probably explains the observed enhancement of the damping rate. The effect of the interface viscoelastic behaviour, induced by adsorbed amphiphilic species on the free oscillations was examined. No significant effect was observed in the experiments conditions (small amplitude oscillations and moderate aging).
This paper exploits the theory of geometric gradient flows to introduce an alternative regularization of the thin-film equation. The solution properties of this regularization are investigated via a sequence of numerical simulations whose results lea
Choosing a suitable model and determining its associated parameters from fitting to experimental data is fundamental for many problems in biomechanics. Models of shear-thinning complex fluids, dating from the work of Bird, Carreau, Cross and Yasuda,
It is commonly accepted that the breakup criteria of drops or bubbles in turbulence is governed by surface tension and inertia. However, also {it{buoyancy}} can play an important role at breakup. In order to better understand this role, here we numer
A Cartesian grid method combined with a simplified gas kinetic scheme is presented for subsonic and supersonic viscous flow simulation on complex geometries. Under the Cartesian mesh, the computational grid points are classified into four different c
We develop a highly efficient numerical method to simulate small-amplitude flapping propulsion by a flexible wing in a nearly inviscid fluid. We allow the wings elastic modulus and mass density to vary arbitrarily, with an eye towards optimizing thes