A laboratory model of splash-form tektites
A laboratory model of splash-form tektites
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DOI：
10.1111/j.1945-5100.2003.tb00317.x
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发表时间：
2003-09-01
影响因子：
2.2
通讯作者：
Bush, JWM
中科院分区：
文献类型：
--
作者：
Elkins-Tanton, LT;Aussillous, P;Bush, JWM
飞溅状玻璃陨石通常被认为具有旋转体的形式。然而，尚未对其形式和稳定性进行详细的流体动力学研究。在这里，我们回顾的动态和稳定性的旋转，翻译液滴，以期作出推论有关的动态历史的玻璃陨石。我们的结论是，除非熔融玻璃陨石和周围环境之间的速度差基本上小于终端速度，熔融玻璃陨石可以存在的平衡机构的革命只有3毫米的大小。较大的玻璃陨石必然是非平衡的形式，因此表明在飞行过程中的冷却和固化的重要性。对旋转、平移液滴形状的研究表明，如果硅酸盐液滴在空气中的旋转速度是其平移速度的1%或更多，则它们将呈现旋转体的形状。只有一个非常小的旋转分量的要求解释了为什么大多数飞溅形式的玻璃陨石对应于旋转体。由滚动或翻滚的熔融金属滴组成的实验室模型再现了所有已知形式的飞溅状玻璃陨石，包括球体，扁椭圆体，哑铃状，泪滴状和圆环状。该实验室还强调了飞行中滚动液滴和翻滚液滴之间的重要区别。例如，环形液滴在前一种情况下比在后一种情况下稳定得多。
Splash-form tektites are generally acknowledged to have the form of bodies of revolution. However, no detailed fluid dynamical investigation of their form and stability has yet been undertaken. Here, we review the dynamics and stability of spinning, translating fluid drops with a view to making inferences concerning the dynamic history of tektites. We conclude that, unless the differential speed between the molten tektite and ambient is substantially less than the terminal velocity, molten tektites can exist as equilibrium bodies of revolution only up to sizes of 3 mm. Larger tektites are necessarily non-equilibrium forms and so indicate the importance of cooling and solidification during flight. An examination of the shapes of rotating, translating drops indicates that rotating silicate drops in air will assume the shapes of bodies of rotation if their rotational speed is 1% or more of their translational speed. This requirement of only a very small rotational component explains why most splash-form tektites correspond to bodies of revolution. A laboratory model that consists of rolling or tumbling molten metallic drops reproduces all of the known forms of splash-form tektites, including spheres, oblate ellipsoids, dumbbells, teardrops, and tori. The laboratory also highlights important differences between rolling drops and tumbling drops in flight. For example, toroidal drops are much more stable in the former than in the latter situation.