Gravitational Dispersion Research Articles

Large amplitude capillary-gravity solitary waves in a stratified fluid sandwiched between two deep homogeneous layers

The study addresses the propagation of plane capillary gravity solitary waves of permanent form in a three layer formulation. The intermediate fluid is assumed to be stratified, while the upper and lower ones are homogeneous and infinitely deep. One or both interfaces separating these layers are subject to capillarity. The research can be applied to the case of two deep fluids when one of these fluids is stratified near the interface. The latter formulation is relevant to studies of capillary gravity waves in the transitional area between sea water and liquid carbon dioxide in the deep ocean. This has become an issue of importance for the secure storage of carbon dioxide, which is an environmental/technological problem in modern days. Therefore, we address a capillary-gravity wave motion beyond the well-examined cases of a free surface or two fluid flows. It is shown that in the considered formulation, capillary-gravity solitary waves of finite amplitude obey an integro-differential equation. This equation contains both Korteweg-de Vries (KdV) and Benjamin-Ono (BO) dispersion laws and a specific nonlinearity, which depends on the properties of the stratified layer. Capillary (KdV-type) dispersion dominates if the thickness of the stratified layer is d≪d∗. When d≫d∗, the gravitational (BO-type) dispersion determines the flow. The value d∗ depends on the mode number, gravitational acceleration, and capillarity effects. Analytical solutions for the amplitude function and the streamline patterns are presented.

Gravitational Dispersion Forces and Gravity Quantization

The parallel development of the theories of electrodynamical and gravitational dispersion forces reveals important differences. The former arose earlier than the formulation of quantum electrodynamics so that expressions for the unretarded, van der Waals forces were obtained by treating the field as classical. Even after the derivation of quantum electrodynamics, semiclassical considerations continued to play a critical role in the interpretation of the full results, including in the retarded regime. On the other hand, recent predictions about the existence of gravitational dispersion forces were obtained without any consideration that the gravitational field might be fundamentally classical. This is an interesting contrast, as several semiclassical theories of electrodynamical dispersion forces exist although the electromagnetic field is well known to be quantized, whereas no semiclassical theory of gravitational dispersion forces was ever developed although a full quantum theory of gravity is lacking. In the first part of this paper, we explore this evolutionary process from a historical point of view, stressing that the existence of a Casimir effect is insufficient to demonstrate that a field is quantized. In the second part of the paper, we show that the recently published results about gravitational dispersion forces can be obtained without quantizing the gravitational field. This is done first in the unretarded regime by means of Margenau’s treatment of multipole dispersion forces, also obtaining mixed potentials. These results are extended to the retarded regime by generalizing to the gravitational field the approach originally proposed by McLachlan. The paper closes with a discussion of experimental challenges and philosophical implications connected to gravitational dispersion forces.

Scale-independent model of gravitational settling of particulate suspension in a fractal channel

Gravitational settling of solid particles into a fractal-shaped channel was investigated experimentally and theoretically. Previous studies have reported that the settling behavior of particles in liquid-filled channels depends strongly on particle properties and suspension conditions. At small particle size and high concentration, particles settle collectively like an immiscible fluid with respect to the surrounding one. In this study, we examined the gravitational dispersion behavior of solid particles in a three-dimensional fractal-shaped channel under various collective conditions. The experimental results showed that the settling behavior varies with the collectivity of suspended particles. In the case of high collectivity conditions, settling velocity is enhanced by a density-driven instability, which depends not only on the physical properties of the particles and fluid but also on channel geometry. We developed a model of temporal change in the volumetric occupancy ratio of the suspended particles region. This model describes the invasion of particles into a fractal channel. Our model comprises only the fractal characteristics of the channel, such as a homothetic ratio and a bifurcation number. Consequently, This model could provide a rough prediction of the gravity-induced invasion behavior of particles into any fractal-shaped channel.

Physical Kinetics of Loop Quantum Gravity and Blackhole Dynamics: Kinetic Theory of Quantum Spacetime, Blackhole Phase Transition Theory and Blackhole Fission.

In the following chapter, a sincere endeavor is made to build a physically as well as in most later aspects a mathematically simple but rigorous physical kinetics of spacetime and of blackholes. Starting with a 3-volume quantization result of the now standard Ashtekar-Lewandowski Quantum Riemannian Geometry, and based on the work of the author on time as a vortex, a 4-volume spacetime quantum, a rapidly fluctuating one is developed and the foundations seem to look shaky in the very beginning, but start to get stronger and stronger as one starts to enter the end of the section on the physical kinetics of blackholes. Thus, experimental tests and observational predictions have been made whenever seem required or appropriate for justification, examples from laboratory table-top physics provided. Once the framework of kinetic theory has been developed, the author has entered into the realm of blackhole phase transitions nucleating from backgroung spacetime as well as other blackhole phase transitions. The equations of phase transitions have been rigorously analyzed and physical interpretations and physical predictions provided. Also certain the Bardeen-Carter-Hawking standard zeroeth law of blackhole dynamics been deduced in the context of equilibrium phase transitions in blackholes. The possibility of splitting of the Kerr-Newman blackhole akin to nuclear fission is obtained. An interesting work is the conception and extensin of the stretched horizon which was constructed by Ashoke Sen in the context of unphysical extremal blackholes in string theory -to that of isolated horizons in the context of arbitrary blackholes as proposed by Rovelli . Quantum gravitational dispersion as well as diffraction of light and gravitational waves by discrete nature of quantum spacetime geometry has been predicted in phenomenology. The paper predicts the gravi-electric Meissner effect in the wake of the Galilean superconductivity in the form of locally Lorentzian spacetimes as a critical behavior in the context of a second order phase transition. The property of the blackholes to undergo fission is demonstrated in the equations of phase transitions. This is used to explain the astrophysical phenomenon of Quasars. An iso-Higgs multiplet is qualitatively predicted as basic constituents of the blackhole. A liquid droplet model is suggested to explain the newly predicted phenomenon of blackhole fission in this paper.The chapter as a whole builds the foundations of the subject of the title of the paper.

Gravitational dispersion in a torsional wave machine

We demonstrate that mechanical waves traveling in a torsional, mechanical wave machine exhibit dispersion due to gravity and the discreteness of the medium. We also show that although the dispersion due to discreteness is negligible, the dispersion due to gravity can be easily measured and can be shown to disappear in a zero-gravity environment.

Airborne Measurement in the Ash Plume from Mount Sakurajima: Analysis of Gravitational Effects on Dispersion and Fallout

Volcanic ash concentrations in the plume from Sakurajima volcano in Japan are observed from airplanes equipped with optical particle counters and GPS tracking devices. The volcano emits several puffs a day. The puffs are also recorded by the Sakurajima Volcanological Observatory. High concentrations are observed in the puffs and fallout driven by vertical air current, called streak fallout. Puffs dispersion is analyzed by the classical diffusion-advection method and a new gravitational dispersion method. The fluid mechanic of the gravitational dispersion, streak fallout, and classical diffusion-advection theory is described in three separate appendices together with methods to find the time gravitational dispersion constant and the diffusion coefficient from satellite photos. The diffusion-advection equation may be used to scale volcanic eruptions so the same eruption plumes can be scaled to constant flux and wind conditions or two eruptions can be scaled to each other. The dispersion analyses show that dispersion of volcanic plumes does not follow either theories completely. It is most likely diffusion in the interface of the plume and the ambient air, together with gravitational flattening of the plumes core. This means larger boundary concentration gradients and smaller diffusion coefficients than state of the art methods can predict.

Regulation of osteogenetic differentiation of mesenchymal stem cells by two axial rotational culture

It is crucial to understand how gravitational force affects the osteogenic differentiation of mesenchymal stem cells (MSCs), and these fundamental aspects hold promise for the development of a novel model of MSC regulation for cell proliferation and differentiation. The objective of this study was to investigate how significantly gravitational dispersion affects the spontaneously induced osteogenic differentiation of MSCs. Expression of surface antigen was measured by flow cytometry prior to two axial rotational cultures. About 12,500 hMSC cells were spread on culture wells of 1.8 cm(2) surface area and incubated for 7 days at 5% CO(2). The culture medium, 10% FCS/DMEM containing 3 ng/ml bFGF, was replaced every 3 days. Four wells then were placed in a 50-ml centrifugal tube filled with 10% FCS/DMEM without bFGF. The centrifugal tube was attached to the center of the rotor, and two axial rotational cultures were started at 10 rpm each of both rotational speeds. It was confirmed that the hMSCs used in this study expressed typical surface antigens as well as a multipotent differentiation ability for either osteogenic or adipogenic differentiation. Spontaneous expression of alkaline phosphatase (Alp) mRNA following the conventional static culture (1G condition) was suppressed by two axial rotational cultures for 7 days (p < 0.05). A separate study indicated that the cell count number eventually increased from 24,700 ± 6,400 to 78,400 ± 18,700 (p < 0.05). In addition, suppressed Alp mRNA was recovered after an additional 7-day culture under static conditions. This result indicated that dispersion of gravity is a promising modality to regulate osteogenic differentiation of hMSCs.

Gravitational wave dispersion in condensed matter systems

The complex index of gravitational wave refraction in condensed matter systems is related to the viscosity response function. Simple applications are discussed for gravitational wave propagation in fluids and crystals.