The shape distribution of splash-form tektites predicted by numerical simulations of rotating fluid drops

Abstract

Splash-form tektites are glassy rocks ranging in size from roughly 1 to 100 mm that are believed to have formed from the splash of silicate liquid after a large terrestrial impact from which they are strewn over thousands of kilometres. They are found in an array of shapes including spheres, oblate ellipsoids, dumbbells, rods and possibly fragments of tori. It has recently become appreciated that surface tension and centrifugal forces associated with the rotation of fluid droplets are the main factors determining the shapes of these tektites. In this contribution, we compare the shape distribution of 1163 measured splash-form tektites with the results of the time evolution of a 3D numerical model of a rotating fluid drop with surface tension. We demonstrate that many aspects of the measured shape distribution can be explained by the results of the dynamical model.

Shapes of rotating superfluid helium nanodroplets

“…The stability diagram and corresponding representative shapes for axially symmetric (D ∞ h ) and two-lobed (D 2h ) branches are shown in Fig. 6 [2,[4][5][6][7]. In Fig.…”

“…The droplets along the twolobed branch are triaxial bodies having D 2h symmetry (a principal C 2 axis, two C 2 rotational axes perpendicular to the principal axis, a horizontal mirror plane perpendicular to the principal axis, and two vertical planes of symmetry). The equilibrium shapes of the prolate droplets at 1.2 < Λ < 2 were calculated numerically [5][6]. The cross sections for the prolate shapes are shown in Fig.…”

“…The characteristic time for developing prolate shapes in rotating classical droplets may be estimated from the results of recent numerical Navier-Stokes calculations [6]. In these calculations, a spherical droplet of radius R was assumed to have a specific angular momentum and the time evolution of its shape was calculated while keeping the angular momentum constant.…”

“…which corresponds to the range of overdamped oscillations [6]. Here η is the kinematic viscosity of the liquid.…”

“…Liquid drop models have also been applied to predict the shapes of rotating atomic nuclei [3]. Equilibrium shapes of classical rotating droplets have been extensively studied theoretically [2,[4][5][6][7] and experimentally [7][8]. A droplet that is spherical at rest acquires an oblate axially symmetric shape upon rotation and, with increasing angular momentum, turns into a two-lobed figure that is elongated perpendicular to the rotational axis, as discussed in more detail in Section 4.…”