Bandgaps in the propagation and scattering of surface water waves over cylindrical steps

圆柱弯月面对毛细波的散射

Scattering of Capillary Waves By a Cylindrical Meniscus

研究毛细波与圆柱弯月面相互作用问题，发现弯月面使波场因折射改变，增加圆柱后阴影区波的存在，且弯月面像有效涂层减慢波速，是表面张力主导波相互作用的重要进展，或影响水生动物生物通讯。

Water wave propagation and scattering over topographical bottoms

Here I present a general formulation of water wave propagation and scattering over topographical bottoms. A simple equation is found and is compared with existing theories. As an application, the theory is extended to the case of water waves in a column with many cylindrical steps.

同心孤波的横向不稳定性

Transverse instability of concentric soliton waves

本文研究同心孤波的横向不稳定性，推导了浅水含表面张力的近同心KdV方程和深水柱坐标下的Gross-Pitaevskii方程，通过奇异特征值分析揭示表面张力与柱几何对不稳定性的关键影响。

On the integrable elliptic cylindrical Kadomtsev-Petviashvili equation

There exist two versions of the Kadomtsev-Petviashvili equation, related to the Cartesian and cylindrical geometries of the waves. In this paper we derive and study a new version, related to the elliptic cylindrical geometry. The derivation is given in the context of surface waves, but the derived equation is a universal integrable model applicable to generic weakly-nonlinear weakly-dispersive waves. We also show that there exist nontrivial transformations between all three versions of the KP equation associated with the physical problem formulation, and use them to obtain new classes of appro…

Limitation in velocity of converging shock wave

The commonly applied self-similar solution of the problem of the converging shock wave (shock) evolution with constant compression of the medium behind the shock front results in an unlimited increase of the medium velocity in the vicinity of the implosion. In this paper, the convergence of cylindrical shocks in water is analyzed using the mass conservation law, when the water compression behind the shock front is a variable. The model predicts a finite range of radii, which depends on the adiabatic index of water and where the increase in pressure exceeds the sum of the change of the kinetic …

Deep water wave cloaking using a multi-layered buoyant plate

Trajectory of surface gravity waves in potential flow regime is affected by the gravitational acceleration, water density, and seabed depth. While the gravitational acceleration and water density are approximately constant, the effect of water depth on surface gravity waves exponentially decreases as the water depth increases. In shallow water, cloaking an object from surface waves by varying the seabed topography is possible, however, as the water depth increases, cloaking becomes a challenge since there is no physical parameter to be engineered and subsequently affects the wave propagation. …

Energy density balance during shock wave implosion in water

Analytical modeling of the evolution of cylindrical and spherical shock waves (shocks) during an implosion in water is presented for an intermediate range of convergence radii. Up to now this range is determined only in experiments observations as a range of implosion radii which are already far from the piston influence, but yet not described by well-known self-similar solutions. The model is based on an analysis of the change in pressure and kinetic energy density, as well as on the corresponding fluxes of internal and kinetic energy densities behind the shock front. It shows that the spatia…

Nonlinear spin-up of a thermally stratified fluid in cylindrical geometries

This is an entry for the Gallery of Fluid Motion of the 62nd Annual Meeting of the APS-DFD (fluid dynamics videos). This video shows the three-dimensional time-dependent incremental spin-up of a thermally stratified fluid in a cylinder and in an annulus. The rigid bottom/side wall(s) are non-slip, and the upper surface is stress-free. All the surfaces are thermally insulated. The working fluid is water characterized by the kinematic viscosity $ν$ and thermal diffusivity $κ$. Initially, the fluid temperature varies linearly with height and is characterized by a constant buoyancy frequency $N$, …

中等振幅的非线性同心水波

Nonlinear concentric water waves of moderate amplitude

本文针对轴对称Boussinesq系统中的非线性同心水波，推导了慢半径cKdV和扩展cKdV模型，并通过数值对比证明扩展cKdV模型能更准确地描述中等振幅波的演化，扩大了弱非线性建模的适用范围。

Surface explosion cavities

We present a fluid dynamics video on cavities created by explosions of firecrackers at the water free surface. We use three types of firecrackers containing 1, 1.3 and 5 g of flash powder. The firecrackers are held with their center at the surface of water in a cubic meter pool. The movies are recorded from the side with a high-speed video camera. Without confinement the explosion produces an hemispherical cavity. Right after the explosion this cavity grows isotropically, the bottom then stops while the sides continue to expand. In the next phase the bottom of the cavity accelerates backwards …

圆柱形容器中重力波的共振三波相互作用

Resonant triad interactions of gravity waves in cylindrical basins

该研究针对有限深度圆柱内重力波展开理论分析，证明水平约束可在特定深度诱发共振三波组，推导了振幅方程并明确演化特性与能量交换参数，对人工及天然水域共振水波研究有潜在价值。