Search

The present study investigates the dynamics of the interface in the presence of a decaying Lamb–Oseen vortex, and four distinct wave patterns are observed: non-breaking waves with small periodic oscillations, plunging breakers, depression breakers, and gravity–capillary waves. The deformation of the interface is induced by a two-dimensional Lamb–Oseen vortex, and the study examines the influence of vortex strength and surface tension on the resulting flow. The wave dynamics are characterized as a function of the Reynolds and Weber numbers, and a phase diagram is presented in terms of (Re , We) to distinguish the different wave patterns. To ensure accurate reconstruction of the interface, the numerical methods used in this study feature a mass and momentum consistent advection method, high-order interpolation schemes, and a block-structured adaptive mesh refinement strategy. The study presents the characteristics of the air cavity entrained at the moment of wave impact for each wave pattern. Furthermore, the results provide insight into the nature of bubble entrainment within a vortex and reveals the bubble entrainment process via a breakup cascade. Meanwhile, it is also shown that the entrainment of bubble results in significant vortex distortion. Overall, this research contributes to enhance our understanding of wave dynamics and the intricate interaction between vortices and interfaces. [ABSTRACT FROM AUTHOR]

In this study, a high-robustness hybrid scheme of weighted essentially non-oscillatory (WENO) scheme with a modified tangent of hyperbola for interface capturing (THINC) algorithm is developed for compressible multicomponent flow on general curvilinear grids. Numerical errors induced by mesh deformation bring loss of numerical accuracy and simulation instability, resulting in inaccurate results such as interface distortion, numerical oscillations or even simulation failure. To address this issue, the WENO scheme combined with an improved THINC strategy is designed to alleviate these errors and maintain the high resolution of interfaces. A modified THINC algorithm is developed for the non-uniform grids, in which the steepness parameter is scaled adaptively according to varying grid spacings. This approach is capable of reducing numerical dissipations for interface reconstruction. The overestimated quasi-conservative WENO formulation are employed to hold the equilibriums of velocity, pressure, and temperature at the material interface. Numerical validations are tested on non-uniform grids with various randomness amplitudes to verify the effectiveness in one- and two-dimensional benchmark problems showing the better performances in shock- and interface-capturing capabilities. [ABSTRACT FROM AUTHOR]

In the present study, high-fidelity simulations of the wake behind a transom stern are performed with a block-based adaptive mesh refinement technology. By transom stern, we mean a square-ended stern of a ship, which is a favorable design for the high-speed ship. The sharp volume of fluid method is adopted to capture the gas–liquid interface, and the immersed boundary method is applied to simulate the boundaries of ship hull. Simulation results show that the V-like diverging wave along with air entrainment constitute the main characteristics of the wake. Air cavity of various scales is captured and tracked by the cavity-detection algorithm. Thus, the spatial and temporal distribution of the number and volume of air cavity is obtained in the simulation. Different draft Froude numbers are considered to analyze their influence on the wake. The wave profile, distribution of air cavity, turbulence kinetic energy, and the air entrainment features of the wakes behind dry and wetted stern are compared quantitatively. Numerical results demonstrate the present solver is capable of reproducing the main characteristics of wake behind a high-speed transom stern. [ABSTRACT FROM AUTHOR]