Research On The Dynamic Characteristics Of Bubble On Superaerophilic Trajectory

Manipulation of a rising bubble in liquids is a topic of intense interest to those involved in the engineered processes recently such as mineral flotation,bubble-column reactor,wastewater treatment,and hydraulic drag reduction.We experimentally studied the motion characteristics of spreading and sliding of adherent bubbles on a superaerophilic straight trajectory(SALT)in horizontal and vertical planes using a high-speed shadowgraphy system.In the horizontal plane,we research on the anisotropic behavior of bubble(2 mm in diameter)spreading on the SALTs of different widths(W=1–5 mm).The 1–3 bounces mostly happened as the bubble approaching the SALTs before its spreading.We first observed that the bubble would be split into two highly symmetrical sub-bubbles with similar migration velocity in opposite directions during the anisotropic spreading after the bubbles finish bouncing.The anisotropic spreading on the narrow SALTs(W ?2 mm with two subregimes)and the wide SALTs(W ?3 mm with four subregimes)influenced by the balance between the surface tension of SALT,Laplace pressure and hydrostatic pressure.Considering the combined effect of the surface tension effect of SALT and Laplace pressure,we have developed a model to predict the radius of the contact size r(t)as a function of time.In the vertical plane,we research on the motion characteristics of sliding of adherent bubbles(1–4.5 mm)on SALTs of different widths(0.5–5 mm).This phase plot can be divided into seven regions concerning the bubble shapes and motions by using W and E(?)tv(?)s number(bubble size)as variables,and five interesting bubble shapes emerge in regions I to V,respectively,including spherical,multimodal,unsteady rupture,double-oscillating-humps and single hump.The trajectory of the bubble center displacement in the spherical region is sinusoidal,and the period is related to the size of the bubble.It is interesting to note that several half-bullet body bubbles,to our knowledge,sliding most rapid(?1 m/s),compared to that in the previous studies,and the rising velocity seems to be mainly determined by SALT width.