Numerical Study for Experiment on Wave Pattern of Internal Wave and Surface Wave in Stratified Fluid

A finite volume method is used to study the generation, propagation and interaction of internal waves in a linearly stratified fluid. The internal waves were generated using single and multiple momentum sources. The full unsteady equations of motion were solved using a SIMPLE scheme on a non-staggered grid. An open boundary, based on the Sommerfield radiation condition, allowed waves to propagate through the computational boundaries with minimum reflection and distortion. For the case of a single momentum source, the effects of viscosity and nonlinearity on the generation and propagation of internal waves were investigated.Internal wave–wave interactions between two wave rays were studied using two momentum sources. The rays generated travelled out from the sources and intersected in interaction regions where nonlinear interactions caused the waves to break. When two rays had identical properties but opposite horizontal phase velocities (symmetric interaction), the interactions were not described by a triad interaction mechanism. Instead, energy was transferred to smaller wavelengths and, a few periods later, to standing evanescent modes in multiples of the primary frequency (greater than the ambient buoyancy frequencies) in the interaction region. The accumulation of the energy caused by these trapped modes within the interaction region resulted in the overturning of the density field. When the two rays had different properties (apart from the multiples of the forcing frequencies) the divisions of the forcing frequencies as well as the combination of the different frequencies were observed within the interaction region.The model was validated by comparing the results with those from experimental studies. Further, the energy balance was conserved and the dissipation of energy was shown to be related to the degree of nonlinear interaction.

Download Full-text

Numerical investigation of internal wave and free surface wave induced by the DARPA Suboff moving in a strongly stratified fluid

Ships and Offshore Structures ◽

10.1080/17445302.2019.1661633 ◽

2019 ◽

Vol 15 (6) ◽

pp. 587-604 ◽

Cited By ~ 1

Author(s):

Weizhuang Ma ◽

Yunbo Li ◽

Yong Ding ◽

Fei Duan ◽

Kaiye Hu

Keyword(s):

Free Surface ◽

Surface Wave ◽

Internal Wave ◽

Numerical Investigation ◽

Stratified Fluid ◽

Free Surface Wave ◽

Wave Induced

Download Full-text

Numerical study on the interaction between the internal and surface waves by a 2D hydrofoil moving in two-layer stratified fluid

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090220974161 ◽

2020 ◽

pp. 147509022097416

Author(s):

Kwan-Woo Kim ◽

Ju-Han Lee ◽

Kwang-Jun Paik ◽

Weoncheol Koo ◽

Young-Gyu Kim

Keyword(s):

Internal Wave ◽

Water Temperature ◽

Mixture Model ◽

Numerical Study ◽

Stratified Flow ◽

Stratified Fluid ◽

Flow Volume ◽

Cfd Model ◽

Vof Model ◽

Submergence Depth

The water temperature in the ocean varies according to its depth and generates a thermocline layer. An internal wave can be excited by an object moving near the thermocline layer because the density changes owing to the water temperature. The internal wave propagates and interacts with the surface wave. This study aims to investigate the internal wave propagation in a two-layer stratified flow, generated by 2D hydrofoil (NACA0012) using a RANS based CFD model. Eulerian multiphase methods were used for the modeling of the two-layer stratified flow; Volume of Fluid (VOF) model and mixture model. A two-layer stratified fluid consisting of air(ρair)-water1(ρw1)-water2(ρw2) is considered instead of the thermocline layer to simplify the numerical simulations. The generation and propagation of the internal wave were investigated, with different configurations of the speed and submergence depth of the hydrofoil. The result suggested that the VOF model shows better agreement with the experimental data compared to the mixture model.

Download Full-text

Surface and interfacial anti-plane waves in micropolar solids with surface energy

Mathematics and Mechanics of Solids ◽

10.1177/1081286520965646 ◽

2020 ◽

pp. 108128652096564

Author(s):

Mriganka Shekhar Chaki ◽

Victor A Eremeyev ◽

Abhishek K Singh

Keyword(s):

Surface Wave ◽

Plane Wave ◽

Numerical Study ◽

Plane Waves ◽

Angular Frequency ◽

Elastic Half Space ◽

Surface Strain ◽

Theoretical Frameworks ◽

Algebraic Form ◽

New Type

In this work, the propagation behaviour of a surface wave in a micropolar elastic half-space with surface strain and kinetic energies localized at the surface and the propagation behaviour of an interfacial anti-plane wave between two micropolar elastic half-spaces with interfacial strain and kinetic energies localized at the interface have been studied. The Gurtin–Murdoch model has been adopted for surface and interfacial elasticity. Dispersion equations for both models have been obtained in algebraic form for two types of anti-plane wave, i.e. a Love-type wave and a new type of surface wave (due to micropolarity). The angular frequency and phase velocity of anti-plane waves have been analysed through a numerical study within cut-off frequencies. The obtained results may find suitable applications in thin film technology, non-destructive analysis or biomechanics, where the models discussed here may serve as theoretical frameworks for similar types of phenomena.

Download Full-text

Numerical study on the spatial and temporal characteristics of nonlinear internal wave energy in the Northern South China sea

Deep Sea Research Part I Oceanographic Research Papers ◽

10.1016/j.dsr.2021.103640 ◽

2021 ◽

pp. 103640

Author(s):

Guangzhen Jin ◽

Zhigang Lai ◽

Xiaodong Shang

Keyword(s):

South China Sea ◽

Internal Wave ◽

South China ◽

Wave Energy ◽

Numerical Study ◽

Northern South China Sea ◽

Nonlinear Internal Wave ◽

Temporal Characteristics ◽

China Sea ◽

Spatial And Temporal Characteristics

Download Full-text

Subharmonic resonance of short internal standing waves by progressive surface waves

Journal of Fluid Mechanics ◽

10.1017/s0022112096007707 ◽

1996 ◽

Vol 321 ◽

pp. 217-233 ◽

Cited By ~ 24

Author(s):

D. F. Hill ◽

M. A. Foda

Keyword(s):

Surface Wave ◽

Internal Wave ◽

Surface Waves ◽

Internal Waves ◽

Growth Rates ◽

Evolution Equations ◽

Standing Waves ◽

Second Order ◽

Inviscid Limit ◽

Initial Growth

Experimental evidence and a theoretical formulation describing the interaction between a progressive surface wave and a nearly standing subharmonic internal wave in a two-layer system are presented. Laboratory investigations into the dynamics of an interface between water and a fluidized sediment bed reveal that progressive surface waves can excite short standing waves at this interface. The corresponding theoretical analysis is second order and specifically considers the case where the internal wave, composed of two oppositely travelling harmonics, is much shorter than the surface wave. Furthermore, the analysis is limited to the case where the internal waves are small, so that only the initial growth is described. Approximate solution to the nonlinear boundary value problem is facilitated through a perturbation expansion in surface wave steepness. When certain resonance conditions are imposed, quadratic interactions between any two of the harmonics are in phase with the third, yielding a resonant triad. At the second order, evolution equations are derived for the internal wave amplitudes. Solution of these equations in the inviscid limit reveals that, at this order, the growth rates for the internal waves are purely imaginary. The introduction of viscosity into the analysis has the effect of modifying the evolution equations so that the growth rates are complex. As a result, the amplitudes of the internal waves are found to grow exponentially in time. Physically, the viscosity has the effect of adjusting the phase of the pressure so that there is net work done on the internal waves. The growth rates are, in addition, shown to be functions of the density ratio of the two fluids, the fluid layer depths, and the surface wave conditions.

Download Full-text

Mesoscale heat waves induced by orography

Advances in Science and Research ◽

10.5194/asr-2-139-2008 ◽

2008 ◽

Vol 2 (1) ◽

pp. 139-143 ◽

Cited By ~ 2

Author(s):

I. Gladich ◽

I. Gallai ◽

D. B. Giaiotti ◽

Gp. Mordacchini ◽

A. Palazzo ◽

...

Keyword(s):

Internal Wave ◽

Heat Waves ◽

Thermal Structure ◽

Thermal Fluctuation ◽

Atmospheric Model ◽

Wave Pattern ◽

Night Time ◽

Thermal Anomalies ◽

Maximum Temperatures ◽

Friuli Venezia Giulia

Abstract. This work is devoted to the analysis of an unusual and sudden thermal fluctuation that interested portions of Friuli Venezia Giulia (Italy) during the night of 27 July 1983. The whole 1983 summer was extremely warm in Europe and in particular on the Italian peninsula, from the Alps down to Sicily. Nevertheless, the day of 27 July 1983 in Friuli Venezia Giulia deserves special attention because the observed maximum temperatures did not occur during day-time but during night-time (from 23:00 up to 24:00 LT, 21:00–22:00 UTC). Peaks of 34.8°C and values of relative humidity of the order of 28% were registered by the official network of weather stations. This event interested mainly the central-eastern part of the plain of Friuli Venezia Giulia, a few kilometers far from the Slovenian border and relieves. The thermal anomalies lasted up to an hour, then temperatures decreased toward values more usual for the climate of the month. The study of this event is carried out with the aid of the AR-WRF numerical atmospheric model, initialized through the ECMWF analysis. The numerical simulations highlight the important role played by orography, jointly with the peculiar thermal structure of the atmosphere, for the enhancing of the internal wave pattern over that area. According to the sensitivity studies realized, the amplification of the internal wave pattern might represent a possible explanation for that meteorological enigma.

Download Full-text