Abstract

A series of exploratory tests were conducted in a cylindrical vessel with a revolving disk at the bottom to investigate the behavior of solitary waves in oil vortices. The formation, transition, stability, symmetrically or asymmetrically rotation of stationarywaveswere explored via post image processing through MATLAB. Fast Fourier Transformation function was applied to investigate the performance of the solitary waves in the vortex pattern.

The Spindle oil with kinematic viscosity of 22.7 cSt was used as the working fluid. The experiments were conducted in a relatively shallow liquid situation with a 10 mm initial liquid
height above the rotating disk.

An abrupt disk velocity change was applied to explore the bifurcation or existence of multiple patterns under the same boundary conditions. Its influence on the formation, transition, and behavior of solitons had also been investigated. Eventually, the angular velocity range for the existence of solitons had been identified.

New Kelvin equilibrium states and also groups of the stationary waves were revealed. A demonstration of 1, 2, 3, 4, 11, 12, and 13 solitons rotating symmetrically around the pattern were also identified. Moreover, the possibility of asymmetrical rotation for solitons and the existence of multiple packets of solitary waves group is presented. The ratio between disk velocity and solitons’ frequency is also calculated and compared.

The Weber number was taken to analyze the results which showed the stability of solitons’ frequency and disk speed ratio at about 0.558 having a very low standard deviation.