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  • Wang, Heng  (5)
  • 1
    Online Resource
    Online Resource
    Splash formation and cavity dynamics of sphere entry through a viscous liquid resting on the water
    AIP Publishing ; 2019
    In:  AIP Advances Vol. 9, No. 7 ( 2019-07-01)
    Details
    In: AIP Advances, AIP Publishing, Vol. 9, No. 7 ( 2019-07-01)
    Abstract: The splash formation and cavity dynamics during the entry of an object into a single-phase liquid system have been investigated considerably in the past, but only a few studies focus on such phenomena in a two-layer liquid system. In the current study, we present an experimental investigation of the entry of a falling sphere into a liquid system consisting of a deep pool of water and a thin layer of dimethicone resting on the water surface. To highlight and support the present findings, experiments of the same sphere entering water were performed and direct comparison were made. As anticipated, the upper-layer viscous liquid introduces a significant change in the splash formation and the differences in behavior are characterized by layered films and wave-like instability structures. In the experiments of the two-layer liquid system, observations show that the early sealing of the splash and the generation of a larger-scale splash fingers are strongly associated with large Froude number, Fr = V0(gD)-1/2 (where V0 is the impact velocity at the still free surface, g is the gravitational acceleration and D is the diameter of the sphere). In addition, the dimensionless cavity depth, the pinch-off depth and the pull-away cavity length behind the sphere are found to be in linear relationship with the Froude number for both water-entry cases and water-dimethicone-entry cases. One of the most interesting results is that the pinch-off time is almost independent of the Froude number. The highly viscous liquid in the upper layer is shown to be critical in determining the cavity dynamics.
    Type of Medium: Online Resource
    ISSN: 2158-3226
    URL: Article
    DOI: 10.1063/1.5109252
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 2583909-3
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Experimental study of the effects of a viscous liquid layer on the cavity dynamics of vertical entry by a sphere into water at low Froude number
    AIP Publishing ; 2021
    In:  Physics of Fluids Vol. 33, No. 1 ( 2021-01-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 33, No. 1 ( 2021-01-01)
    Abstract: The water entry process is relevant to a wide range of engineering applications and has been extensively investigated. Most liquids used in such studies are single-layered, and little attention has been paid to how the structure of a two-layer liquid system affects the splash and cavity formation. In this study, we use high-speed photography to experimentally investigate the water entry of a sphere after it has passed vertically through a layer of highly viscous liquid (dimethicone) at a low Froude number. We investigate the effects of different thicknesses of this dimethicone layer and find that the formation of the splash crown is closely related to both the thickness and the Froude number. In a certain range of dimethicone thickness, the height of the splash interface decreases with the increasing thickness and increases with the decreasing Froude number. The dimensionless interface height at the pinch-off time is found to have a linear relationship with the dimensionless initial velocity of the sphere. Furthermore, the formation of the cavity, including its length and pinch-off depth, depends on the Froude number. However, the pinch-off time is almost independent of the dimethicone thickness and the Froude number, and the cavity length is nearly independent of the dimethicone thickness for all Froude numbers examined.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0032818
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 3
    Online Resource
    Online Resource
    Cavity dynamics of vertical water entry of a truncated cone–cylinder body with different angles of attack
    AIP Publishing ; 2021
    In:  Physics of Fluids Vol. 33, No. 5 ( 2021-05-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 33, No. 5 ( 2021-05-01)
    Abstract: This paper investigates the evolution of the flow field and the load characteristics of a revolving body water entry at different angles of attack through experiments and numerical calculations. The experiment used a high-speed camera and pressure measurement devices to measure the flow field and surface pressure of water entry. A numerical calculation model was established using the computational fluid dynamics method and was used to simulate a test case. The results show that a change in the attack angle significantly affects the flow field and load characteristics of the revolving body. An increase in the angle reduces the cavity area on the upstream surface and delays the surface seal of the splash crown. The larger the angle, the smaller the difference between the peak impact pressures of adjacent cases, and the longer the time for the peak to reach a stable value (which increases approximately linearly). Meanwhile, the surface load of the revolving body is mainly concentrated around the cavity separation line, and the pressures before and after that line become dramatically different. The bottom surface load propagates from upstream to downstream in the form of ripples. Moreover, during the water entry process, the vortices around the body change from large scale to small scale. The vortices are densely attached to the surface and move upward along the test body. Interestingly, when the velocity field forms whirlpool at the wall, the surface pressure is usually less than the ambient pressure. These findings provide an important basis for a better understanding of the evolution of the flow field and surface load in the process of water entry, and further clarify the relationship between them.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0051703
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 4
    Online Resource
    Online Resource
    Numerical Investigation on the Deformation of the Free Interface During Water Entry and Exit of a Circular Cylinder by Using the Immersed Boundary-Multiphase Lattice Boltzmann Flux Solver
    Springer Science and Business Media LLC ; 2022
    In:  Journal of Marine Science and Application Vol. 21, No. 3 ( 2022-09), p. 99-113
    Details
    In: Journal of Marine Science and Application, Springer Science and Business Media LLC, Vol. 21, No. 3 ( 2022-09), p. 99-113
    Abstract: In this work, the deformation of free interface during water entry and exit of a circular cylinder is investigated numerically by using the two-dimensional (2D) immersed boundary-multiphase lattice Boltzmann flux solver (IB-MLBFS). The fluid domain is discretized by finite volume discretization, and the flux on the grid interface is evaluated by lattice Boltzmann equations. Both the implicit velocity correction and the surface flux correction are implemented by using the immersed boundary-method to consider the fluid-structure interaction and the contact interface between the multiphase fluids and the structure. First, the water entry of a circular cylinder is simulated and the results are compared with the experiment, which considered the length-diameter ratio of the circular cylinder. The reliability of 2D simulation is verified and the deformation of the free interface is well investigated. Afterward, the water exit of a circular cylinder with constant velocity is simulated, which is less researched. In addition, the results show the advantage of present IB-MLBFS to some extent. Finally, the water exit and re-entry of a circular cylinder are presented, and the results present the complex deformation of the free interface and the dynamic response of the moving structure. Based on the numerical results, the free interface of the multiphase fluids is well captured, and the contact interface on the boundary of the moving structure is accurately presented by the IB-MLBFS.
    Type of Medium: Online Resource
    ISSN: 1671-9433 , 1993-5048
    URL: Article
    DOI: 10.1007/s11804-022-00292-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2391013-6
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  • 5
    Online Resource
    Online Resource
    Experimental study on the influence of the angle of attack on cavity evolution and surface load in the water entry of a cylinder
    Elsevier BV ; 2021
    In:  Ocean Engineering Vol. 219 ( 2021-01), p. 108271-
    Details
    In: Ocean Engineering, Elsevier BV, Vol. 219 ( 2021-01), p. 108271-
    Type of Medium: Online Resource
    ISSN: 0029-8018
    URL: Article
    DOI: 10.1016/j.oceaneng.2020.108271
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1498543-3
    detail.hit.zdb_id: 160791-1
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