On a rotational flow disturbed by gravity

1976 ◽  
Vol 74 (2) ◽  
pp. 335-351 ◽  
Author(s):  
H. P. Greenspan
Keyword(s):  
Symmetry Axis ◽  
Flow Instability ◽  
Fluid Motion ◽  
Rotational Flow ◽  
Rotating Fluids ◽  
Rotation Symmetry ◽  
Gravitational Forces ◽  
Parameter Ranges ◽  
Relationship Of ◽  
The Relationship

We examine a rapidly rotating flow that exhibits periodic vortex detachment. Specifically, the rotation/symmetry axis of a fluid-filled cylinder is set perpendicular to gravity. A free buoyant cylindrical float placed within the container is acted upon by both centrifugal and gravitational forces, the competition of which causes fluid motion and, in certain parameter ranges, flow instability. The motion is determined, a criterion for separation is advanced, preliminary experiments and data are described and the relationship of this phenomenon to other examples of vortex shedding in rotating fluids is discussed.

scholarly journals The physical nature of heterogeneity of the composition of river water

2019 ◽  
Vol 484 (5) ◽  
pp. 605-609
Author(s):  
Yu. D. Chashechkin ◽  
O. M. Rosenthal
Keyword(s):  
Complete System ◽  
Fluid Motion ◽  
Physical Nature ◽  
Spatial And Temporal Variability ◽  
River Waters ◽  
Environmental Processes ◽  
Hydrodynamic Structure ◽  
Relationship Of ◽  
The Relationship ◽  
Significant Factors

Experimental data are presented to show that the spatial and temporal variability of the composition of river waters cannot be explained solely by the influence of sources and effluents of the substances and that there are additional significant factors that support or even initiate the dispersion of the concentration of pollutants here. This variation is reflected in the resources and the economic characteristics of the rivers; so identification of its reason is important. Thus, the hydrodynamic structure of the water flow is studied by analyzing the complete system of equations of fluid motion mechanics. The completed work allowed us to show that the elements of this structure are waves, vortices, and highly gradient layers (ligaments), presumably creating the described dispersion effect. Further investigation of the relationship of the precise hydrodynamic and hydrochemical structures of river waters will contribute to better understanding of the water-environmental processes, ensuring the perfection of water management methods.

A Decade's Investigation of the Stability of Erodible Stream Beds

1976 ◽  
Vol 7 (3) ◽  
pp. 161-180 ◽  
Author(s):  
A. J. Reynolds
Keyword(s):  
Current Level ◽  
Rotational Flow ◽  
Flow Models ◽  
Stream Beds ◽  
Phase Lags ◽  
The Stability ◽  
Level Of Understanding ◽  
Relationship Of ◽  
The Relationship ◽  
Stream Bed

This paper reviews work on the stability of a particulate stream bed to the erosive attack of a flow with a free surface. Attention is given to the development of the hydraulic, the potential-flow and the rotational-flow models, and to the roles of phase lags and transport laws. The relationship of the stability theory to the ultimate form of the stream bed is discussed, and the current level of understanding of bed features is examined. Some investigations relating to a wider range of erosive processes are noted, and an extensive bibliography is provided.

scholarly journals Gravity and Inertia in General Relativity

2021 ◽  
Author(s):  
James F. Woodward
Keyword(s):  
General Relativity ◽  
Equivalence Principle ◽  
Gravitational Effect ◽  
Inertial Forces ◽  
Gravitational Effects ◽  
Gravitational Forces ◽  
Ernst Mach ◽  
Relationship Of ◽  
The Relationship ◽  
The Universe

The relationship of gravity and inertia has been an issue in physics since Einstein, acting on an observation of Ernst Mach that rotations take place with respect to the “fixed stars”, advanced the Equivalence Principle (EP). The EP is the assertion that the forces that arise in proper accelerations are indistinguishable from gravitational forces unless one checks ones circumstances in relation to distant matter in the universe (the fixed stars). By 1912, Einstein had settled on the idea that inertial phenomena, in particular, inertial forces should be a consequence of inductive gravitational effects. About 1960, five years after Einstein’s death, Carl Brans pointed out that Einstein had been mistaken in his “spectator matter” argument. He inferred that the EP prohibits the gravitational induction of inertia. I argue that while Brans’ argument is correct, the inference that inertia is not an inductive gravitational effect is not correct. If inertial forces are gravitationally induced, it should be possible to generate transient gravitational forces of practical levels in the laboratory. I present results of a experiment designed to produce such forces for propulsive purposes.

On the instability of natural convection flow on inclined plates

1970 ◽  
Vol 42 (3) ◽  
pp. 465-470 ◽  
Author(s):  
J. R. Lloyd ◽  
E. M. Sparrow
Keyword(s):  
Flow Instability ◽  
Fluid Motion ◽  
Convection Flow ◽  
Visualization Technique ◽  
Natural Convection Flow ◽  
Continuous Transition ◽  
Longitudinal Vortices ◽  
Inclination Angles ◽  
Inclined Plates ◽  
The Relationship

Experiments are carried out to establish the relationship between the nature of the flow instability and the inclination angle of the plate. The angular dependence of the Rayleigh number characterizing the onset of instability is also determined. An electrochemical flow visualization technique is utilized to expose the patterns of fluid motion. It is found that for inclination angles of less than 14° (relative to the vertical), waves are the mode of instability. On the other hand, for inclination angles in excess of 17°, the instability is characterized by longitudinal vortices. The range between 14° and 17° is a zone of continuous transition, with the two modes of instability co-existing.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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