Nearly 150 years ago, Lord Kelvin proposed the isotropic helicoid, a particle with isotropic yet chiral interactions with a fluid so that translation couples to rotation. An implementation of his design fabricated with a three-dimensional printer is found experimentally to have no detectable translation-rotation coupling, although the particle point-group symmetry allows this coupling. We explain these results by demonstrating that in Stokes flow, the chiral coupling of such isotropic helicoids made out of nonchiral vanes is due only to hydrodynamic interactions between these vanes. Therefore it is small. In summary, Kelvin's predicted isotropic helicoid exists, but only as a weak breaking of a symmetry of noninteracting vanes in Stokes flow.

中文翻译：

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开尔文勋爵的各向同性螺旋面

大约 150 年前，开尔文勋爵提出了各向同性螺旋体，这是一种与流体具有各向同性但手性相互作用的粒子，因此平移与旋转耦合。实验发现，他的设计的一个实现是用 3D 打印机制造的，没有可检测的平移-旋转耦合，尽管粒子点群对称性允许这种耦合。我们通过证明在斯托克斯流中解释这些结果，这种由非手性叶片制成的各向同性螺旋体的手性耦合仅归因于这些叶片之间的流体动力学相互作用。因此它很小。总之，开尔文预测的各向同性螺旋面存在，但只是作为斯托克斯流中非相互作用叶片对称性的弱破坏。