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Numerous laboratory-scale physical experiments and numerical simulations have been carried out to explore the shoaling dynamics of internal solitary waves (ISWs) on slope topographies. Detailed features during wave breaking have been investigated under relatively low Reynolds numbers, but for real ocean-scale or lake-scale scenarios with a much higher Reynolds number, laboratory-scale modeling is inadequate to capture the three-dimensional turbulent characteristics in the wave shoaling process. As a result, a three-dimensional large-eddy simulation (LES) is performed in the present study to investigate the shoaling process of the elevation-typed ISWs traveling on uniform slopes in a two-layer fluid system. Scale effects due to the Reynolds numbers (varied from 103 to 105) and three-dimensional characteristics during wave shoaling are also explored and discussed. Detailed ISW-slope interaction dynamics, including the typical shoaling features, the characteristics of internal boluses, and both the velocity field and the energy transformation, are systematically obtained and analyzed. It is found that, while reaching the maximum vertical displacement (i.e., maximum run-up height), the frontal part of the heavier lower-layer fluid can evolve into the internal bolus if the internal Iribarren number, Ir, defined as the ratio of the topographic slope and the square root of the incident wave steepness, is less than 0.65. The maximum wave-induced velocities and energy loss are also well related to Ir. Empirical regressed equations for seven important physical parameters during the shoaling process are also proposed. The extreme velocities, wave energy loss, and three-dimensionality of the flow field are all identified to be very sensitive to Reynolds numbers, indicating that traditional two-dimensional laboratory-scale modeling tools may be insufficient to accurately capture the shoaling mechanisms of the ISWs of elevation type. [ABSTRACT FROM AUTHOR]

Buoyant plumes from different river mouths extensively collide and converge in coastal areas worldwide, but these interactions and dynamics have not been extensively studied. Plume-to-plume interactions have been mainly investigated using hydrostatic simulations so far, which have limitations in terms of flow structure resolution. This study conducts a comprehensive investigation on both hydrostatic and nonhydrostatic simulations to understand the dynamics of the frontal collision of two buoyant plumes. The results show that nonhydrostatic simulations distinctly differ from hydrostatic simulations. Moreover, nonhydrostatic simulations yield plume evolutions that are more in line with the physical reality and field observations in terms of the flow structures. Nonhydrostatic simulations reveal bore-like structures at the rear of the plume front, clearly exhibiting their effects on the shape evolution and interfacial entrainment. Furthermore, the existing classification of plume collision is reexamined, and the basic dynamics and collision types under nonhydrostatic simulations are elucidated. Additionally, dynamic pressure characteristics are investigated, which suggests that dynamic pressure is the key to the generation and evolution of vortex structures. [ABSTRACT FROM AUTHOR]

Simultaneous existence of solute gradients along with temperature gradients in a double diffusive system is favorable to the onset of salt finger convection and this phenomenon has been investigated for several decades due to its efficient mixing mechanism. However, relatively few works were focused on the double diffusive process through a fluid-saturated porous interface (FPI), which could be applied in a variety of scenarios such as the directional solidification of concentrated alloys or mixing zones in coastal freshwater aquifers. In this paper, we consider the evolution of double-diffusive salt finger through FPI with a single-domain approach adopted for the solution of flow in a composite region made up of a fluid layer overlying a porous layer. Comparisons with existing numerical results show great agreement and demonstrate that flows through a fluid–porous system can be predicted with good accuracy by the proposed method. Several cases spanning a range of initial buoyancy ratio N 0 from 2 to 7 are conducted to study the structure and behavior of salt finger together with key issues being focused on the effect of initial buoyancy ratio on flux variations. Differing from in stratified fluid layers, salt finger through FPI shows an asymmetric structure in which the growth rate in the fluid layer is much greater and the finger column in the porous layer presents a squarer shape. It is found that under the condition of low initial buoyancy ratios, the potential energy stored in the unstable stratification of salinity converted more into kinetic energy, which enhances the mixture of heat and masses in the vertical direction. [ABSTRACT FROM AUTHOR]

Salt fingers as a mixing mechanism in the ocean have been investigated for several decades, together with a key issue being focused on their convective evolution and flux ratio variation. However, related studies on tilting fingers in the ocean produced by shear flow have been ignored by previous researchers. In this paper, a 2-D numerical model is presented to study the evolution of the double-diffusion salt finger in a two-layer thermohaline system with laminar shear flow. The model is divided into a steady-state solver and double-diffusion convection system, aimed to reveal the effect of shear flow on salt fingers and analyze the mechanism behind the shear and fingers. Several cases are conducted for Re = 0 ∼ 900 to study the evolution of salt fingers in a laminar shear flow and the variation of salt flux with Re. The results show that salt fingers exist and tilt in the presence of laminar shear flow. The mass transport in the vertical direction is weakened as the Reynolds number increases. An asymmetric structure of the salt finger is discovered and accounts for the morphological tilt and salt flux reduction. [ABSTRACT FROM AUTHOR]