The impacts of solid spheres with the free surface have been studied for over one hundred years. In this thesis, the Worthington jets resulting from the impacts of hydrophobic and hydrophilic spheres with the free surface are studied experimentally. Several impact velocities and three materials of differing mass ratios are used. The resulting jets are characterized in terms of common non-dimens...

An optimal motion planning of a free-falling cat based on the spline approximation is investigated. Nonholonomicity arises in a free-falling cat subjected to nonintegrable velocity constraints or nonintegrable conservation laws. The equation of dynamics of a free-falling cat is obtained by using the model of two symmetric rigid bodies. The control of the system can be converted to the motion pl...

Fast liquid jets, called micro-jets, are produced within cavitation bubbles experiencing an aspherical collapse. Here we review micro-jets of different origins, scales and appearances, and propose a unified framework to describe their dynamics by using an anisotropy parameter ζ > 0, representing a dimensionless measure of the liquid momentum at the collapse point (Kelvin impulse). This paramete...

Hydraulic jumps at the tail end of spillways are usually induced by baffle blocks or other obstacles. Such jumps can also be induced by jets that oppose the main flow. Another application is to back up turbidity currents in reservoirs by means of opposing jets. This measure can be adopted when transfer tunnels feed water into the reservoir at a higher elevation near the dam. Stopping the turbid...

A radio core represents the peak of intensity in VLBI images and is located at the base of jets. It appears at different positions depending on frequencies. This is known as “core shift”, caused by absorption of the core emission. The position of the central engine in an AGN can be estimated accurately by measuring the core shift with multifrequency and phase-referencing observations. We observ...