arXiv subjects

Kazuki Yoshikawa

Publications and source records attributed to Kazuki Yoshikawa.

2 recordsLinked to original sources

arXiv2023

Numerical reproduction of the spiral wave visualized experimentally in a wide-gap spherical Couette flow

SCF experiments were conducted according to the work of Egbers and Rath [Acta Mech. 111 pp. 125--140 (1995)]. Through visualization using aluminium flakes drifting on a horizontal plane illuminated by a laser sheet, the flow was identified as a spiral wave with azimuthal wavenumber $m=3$, using the experimentally obtained and numerically deduced comparison between phase velocities. By solving the equation of motion for the infinitesimal planar particles advecting in the flow field of the spiral wave, a visual distribution of reflected light was reproduced virtually, which is in good agreement with the picture obtained experimentally.

physics.flu-dyn↗

arXiv2022

A thermal convection limit of spiral state in wide-gap spherical Couette flow

The symmetries of flow structures are often prescribed by their mechanical instability and geometry. Here, as an example, we present the homotopy of the rotating 3-fold spiral state that is robust in a spherical Couette flow towards the hybrid system with a thermal stratification effect. It has not yet been confirmed that the rotating wave state smoothly connects to the thermal stratification system. Through continuation, the most dangerous mode at a purely spherical Couette flow of $m=4$ modes of spherical harmonics is replaced by $l=4$ and $m=3$ in a purely thermal convective system. For the state obtained at the limit under only the thermal effect, the residual quantities of both the torque to the outer sphere and meridional circulation are discussed in detail.

physics.flu-dyn↗