Saltaion of Blown Sand Particles and Wind-Velocity Distribution

This article analyzes the factors that influence the deformation process in the channel. When assessing the deformation process in channels consisting of disconnected soils, the method for determining nonwashable speed was analyzed, taking into account the trapezoidal shape of the channel, and, based on laboratory studies, a dependence was proposed for determining the non-washable speed. The values of the proposed dependencies are compared with the calculated values of the formulas of I.I. Levi, C.E. Mirtskhulava, V.A. Velikanova, B.I. Studenichnikov and A.M. Latyshenkov and obtained positive results. The proposed dependencies for the determination of non-washable speed are improved, taking into account turbulence and the laws of velocity distribution over the stream's depth. In the experimental researches, were used sand particles with different diameters d ≤ 0.315mm; 0.315mm < d ≤ 0.63mm; 0.63mm < d ≤1.25mm 1.25mm < d ≤ 2.5mm 2.5mm < d ≤ 5.0mm. Based on the analysis of the experimental data, the coefficients are as follows: η1 = 1.41 for the bottom of the channel and η2 = 1.52 for side slopes. The reliability of the results is justified by comparing the proposed calculation method with a study of other authors. Based on the research, constructed a plot of the velocity distribution and the depth of the stream. In these diagrams, preservation of the change in velocity along the depth of the flow was observed under various modes of motion. In all experiments, a process was observed-the smallest value of the flow velocity at the bottom and the highest at a depth of (0.8–0.9) h from the water level.

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Solar wind velocity distribution on the heliospheric current sheet during Carrington rotations 1787-1795

Annales Geophysicae ◽

10.1007/s00585-995-0807-3 ◽

1995 ◽

Vol 13 (8) ◽

pp. 807-814

Author(s):

B. Bala ◽

S. R. Prabhakaran Nayar

Keyword(s):

Solar Wind ◽

Velocity Distribution ◽

Current Sheet ◽

Wind Velocity ◽

Solar Wind Velocity ◽

Neutral Line ◽

Coronal Magnetic Field ◽

Heliospheric Current Sheet ◽

Source Surface ◽

Low Speed

Abstract. The solar wind velocity distribution in the heliosphere is best represented using a v-map, where velocity contours are plotted in heliographic latitude-longitude coordinates. It has already been established that low-speed regions of the solar wind on the source surface correspond to the maximum bright regions of the K-corona and the neutral line of the coronal magnetic field. In this analysis, v-maps on the source surface for Carrington rotations (CRs) 1787–1795, during 1987, have been prepared using the interplanetary scintillation measurements at Research Institute of Atmospherics (RIA), Nagoya Univ., Japan. These v-maps were then used to study the time evolution of the low-speed (\\leq450 km s–1) belt of the solar wind and to deduce the distribution of solar wind velocity on the heliospheric current sheet. The low-speed belt of the solar wind on the source surface was found to change from one CR to the next, implying a time evolution. Instead of a slow and systematic evolution, the pattern of distribution of solar wind changed dramatically at one particular solar rotation (CR 1792) and the distributions for the succeeding rotations were similar to this pattern. The low-speed region, in most cases, was found to be close to the solar equator and almost parallel to it. However, during some solar rotations, they were found to be organised in certain longitudes, leaving regions with longitudinal width greater than 30° free of low-speed solar wind, i.e. these regions were occupied by solar wind with velocities greater than 450 km s–1. It is also noted from this study that the low-speed belt, in general, followed the neutral line of the coronal magnetic field, except in certain cases. The solar wind velocity on the heliospheric current sheet (HCS) varied in the range 300–585 km s–1 during the period of study, and the pattern of velocity distribution varied from rotation to rotation.

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