In 1871, Lord Kelvin proposed a stimulating model of an isotropic helicoid. The isotropic helicoid has rotational invariance but not reflection invariance, offering the possibility of the translation-rotation coupling for an isotropic particle. However, no one has been able to detect the coupling of an isotropic helicoid that is non-zero within the accuracy of the measurement. New theory quantitatively predicts a tiny coupling of the isotropic helicoid in the low Reynolds number regime for about only 0.4% of the coupling of its corresponding anisotropic helicoid (Collins, Darci, et al. \"Lord Kelvin's isotropic helicoid.\" arXiv preprint arXiv:2006.08282 (2020)). In this thesis, we build a new experimental apparatus to quantitatively measure the translation-rotation coupling of Lord Kelvin's isotropic helicoid. Our data indicate that the apparatus is able to measure a tiny torque acting on the particle very accurately. From our data, the ratio of the translation-rotation coupling of Lord Kelvin's isotropic helicoid and anisotropic helicoid with the maximum coupling is 3.33% in the left-handed direction for the particle oriented in the vertical axis and 1.97% in the right-handed direction for the particle oriented in the diagonal axis. The random uncertainty in our measurement of the coupling of the isotropic helicoid is 0.27% of that of the anisotropic helicoid (3.3% coupling effect with 8% uncertainty), which is substantially better than the previous best measurement with 1% random uncertainty. However, the measured translation-rotation coupling of the particle is different in signs for the two different orientations. Theory suggests that the coupling should be isotropic, so we believe that there are some anisotropies in our experimental apparatus that lead to our anisotropic coupling measurements. We identify the wire involved in holding the test particle as a major contributor to this breaking in isotropy of the apparatus and the orientation dependence of the coupling in our data. In future work, we will use numerical simulations to quantify the effect of the wire.
"},{"label":"Degree","value":["Bachelor of Arts with Departmental Honors"]},{"label":"Author-supplied Keywords","value":["Translation-rotation coupling","Isotropic helicoid"]},{"label":"Administrative Note","value":"Drupal Node ID: 24302