This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured b...This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured by using a Polytec Laser Vibrometer with a thin layer of aluminium powder scattering on the surface to reflect the laser beam. Nonlinear interaction processes result in a stationary Fourier spectrum of the vertical surface velocities （the same as the surface elevation）, i.e. Iω -ω^-3-5. The observed spectrum can be interpreted as a wave-turbulent Kolmogorov spectrum for the case of ‘narrowband pumping＇ for a direct cascade of energy. Correlation dimension analysis of the whole development process reveals four distinct stages during the wave structure development and identifies the wave turbulence stage.展开更多
A new method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension. The nonlinear surface is expressed by Fourie...A new method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension. The nonlinear surface is expressed by Fourier series with finite number of terms, after the computational domain is transformed into a unit circle. The dynamic boundary equation is used in its exact nonlinear form and the coefficients of Fourier series are found by the Newton-Raphson method successively. This is a neat method, Yielding high prescision with little computational effort.展开更多
In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak...In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak restrictions, the particle motion at the sea surface and energy transmission may be obtained from a wave record. The analysis show that for the two-dimensional and narrow-band mo- tion (or a physical phenomena, such as capillary waves breaking, which satisfy the narrow-band approx- imation) the local kinetic energy fluctuates in time as the envelope equared multiplied by a constant factor and can be obtained directly from a wave record. It is pointed that the local fluctuatiom of the potential energy as well as the local fluctuations of the total energy can be separated into a slowly varying part and a more rapid oscillating Part. Both Parts can be evaluated by meaas of the Hilbert transform. Finally, a physical interpretation of the envelope of the two-dimensional capillary waves as well as the method for wave group analysis is presented.展开更多
Transmission beam can be modulated at the liquid-liquid interface inside an electrowetting liquid lens.The fluctuation characteristics of the interface has a decisive effect on the beam modulation.A closed cylinder in...Transmission beam can be modulated at the liquid-liquid interface inside an electrowetting liquid lens.The fluctuation characteristics of the interface has a decisive effect on the beam modulation.A closed cylinder in capillary constant scale is analyzed and the natural frequencies of a flat interface are obtained using capillary wave hydrodynamics.Results in modes 0 and 1 are in good agreement with previous experiments in the literature.The influences of the radius,the height ratio and the height-to-diameter ratio of a liquid lens on the interface eigenfrequencies are analyzed.展开更多
This paper conducted an experimental study of droplet behavior characteristics occurring within a burning aviation kerosene droplet and on the droplet interface.The droplet combustion was performed in a quiescent high...This paper conducted an experimental study of droplet behavior characteristics occurring within a burning aviation kerosene droplet and on the droplet interface.The droplet combustion was performed in a quiescent high-temperature environment by means of the droplet suspension technique.The soot particles were used as tracers to visualize the fluid motion in the droplet.The shape variation of droplet,internal flow pattern in the burning droplet,and instabilities at gas-liquid phase interface were recorded by a high speed camera.The internal fluid flow in the droplet was revealed to be caused by the Marangoni effect,which was generated because of the surface tension gradient induced by the temperature gradient on the droplet surface.The studies showed that the Marangoni effect has a significant impact on the internal flow.The amplitude of the capillary waves on the surface of the droplet was non-uniform and presented the amplitude characteristics of large-small-some.The wavelength of the capillary waves for burning aviation kerosene droplet ranged from 110μm to 120μm.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10087101)the National Science Fund for Distinguished Young Scholars (Grant No 10525208)
文摘This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured by using a Polytec Laser Vibrometer with a thin layer of aluminium powder scattering on the surface to reflect the laser beam. Nonlinear interaction processes result in a stationary Fourier spectrum of the vertical surface velocities （the same as the surface elevation）, i.e. Iω -ω^-3-5. The observed spectrum can be interpreted as a wave-turbulent Kolmogorov spectrum for the case of ‘narrowband pumping＇ for a direct cascade of energy. Correlation dimension analysis of the whole development process reveals four distinct stages during the wave structure development and identifies the wave turbulence stage.
文摘A new method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension. The nonlinear surface is expressed by Fourier series with finite number of terms, after the computational domain is transformed into a unit circle. The dynamic boundary equation is used in its exact nonlinear form and the coefficients of Fourier series are found by the Newton-Raphson method successively. This is a neat method, Yielding high prescision with little computational effort.
文摘In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak restrictions, the particle motion at the sea surface and energy transmission may be obtained from a wave record. The analysis show that for the two-dimensional and narrow-band mo- tion (or a physical phenomena, such as capillary waves breaking, which satisfy the narrow-band approx- imation) the local kinetic energy fluctuates in time as the envelope equared multiplied by a constant factor and can be obtained directly from a wave record. It is pointed that the local fluctuatiom of the potential energy as well as the local fluctuations of the total energy can be separated into a slowly varying part and a more rapid oscillating Part. Both Parts can be evaluated by meaas of the Hilbert transform. Finally, a physical interpretation of the envelope of the two-dimensional capillary waves as well as the method for wave group analysis is presented.
文摘Transmission beam can be modulated at the liquid-liquid interface inside an electrowetting liquid lens.The fluctuation characteristics of the interface has a decisive effect on the beam modulation.A closed cylinder in capillary constant scale is analyzed and the natural frequencies of a flat interface are obtained using capillary wave hydrodynamics.Results in modes 0 and 1 are in good agreement with previous experiments in the literature.The influences of the radius,the height ratio and the height-to-diameter ratio of a liquid lens on the interface eigenfrequencies are analyzed.
文摘This paper conducted an experimental study of droplet behavior characteristics occurring within a burning aviation kerosene droplet and on the droplet interface.The droplet combustion was performed in a quiescent high-temperature environment by means of the droplet suspension technique.The soot particles were used as tracers to visualize the fluid motion in the droplet.The shape variation of droplet,internal flow pattern in the burning droplet,and instabilities at gas-liquid phase interface were recorded by a high speed camera.The internal fluid flow in the droplet was revealed to be caused by the Marangoni effect,which was generated because of the surface tension gradient induced by the temperature gradient on the droplet surface.The studies showed that the Marangoni effect has a significant impact on the internal flow.The amplitude of the capillary waves on the surface of the droplet was non-uniform and presented the amplitude characteristics of large-small-some.The wavelength of the capillary waves for burning aviation kerosene droplet ranged from 110μm to 120μm.
