scholarly journals Nonlinear Shear Effects of the Secondary Current in the 2D Flow Analysis in Meandering Channels with Sharp Curvature

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1486
Author(s):  
Jaehyun Shin ◽  
Il-Won Seo
Keyword(s):  
Velocity Profile ◽  
Secondary Flow ◽  
Vertical Velocity ◽  
Large Scale ◽  
Shear Effect ◽  
Meandering Channel ◽  
Meandering Channels ◽  
Vertical Velocity Profile ◽  
Shear Effects ◽  
Nonlinear Shear

In order to analyze the shear effect of secondary currents on the flow structures in a meandering channel, this research developed a two-dimensional shallow water model, which included the dispersion stress term accounting for the shear effect in the vertical velocity profile. A new equation for the vertical velocity profile that included nonlinear shear effects was derived from the equation of motion in the meandering channel with sharp curvature. Using the experiment data obtained from large-scale meandering channels, the ratio of the depth over the radius-of-curvature was incorporated into the shear intensity of the secondary flow in the proposed equation. Comparisons with the experimental results by Rozovskii (1957) showed that the computed values of the primary velocity distribution by the proposed model showed better fit with the observed data than the simulations with linear models and models without secondary flow consideration. The simulated results in the large-scale meandering channels demonstrated that simulations with the nonlinear secondary flow effect added into modeling gave higher accuracy, reducing the relative error by 19% in reproducing the skewed distributions of the primary flow in meandering channels, particularly in the regions where the effects from spiral motion were strong, due to sharp meanders.

scholarly journals Weakly Forced Mock Walker Cells

2012 ◽  
Vol 69 (9) ◽  
pp. 2759-2786 ◽  
Author(s):  
Zhiming Kuang
Keyword(s):  
Velocity Profile ◽  
Vertical Velocity ◽  
Large Scale ◽  
Domain Size ◽  
Momentum Balance ◽  
Convective Heating ◽  
Temperature Anomalies ◽  
Vertical Velocity Profile ◽  
Horizontal Momentum ◽  
Vertical Scales

Abstract Mock Walker cells driven by weak sea surface temperature (SST) forcing are studied using planetary-scale cloud system–resolving simulations and a simplified framework that represents convection with its linear response functions and parameterizes the large-scale flow based on the gravity wave equation. For sinusoidal SST forcings of the same amplitude, as the horizontal domain size increases, the mock Walker cells strengthen substantially and shorter vertical scales in the vertical velocity profile diminish. This is explained by the fact that temperature anomalies required to sustain a vertical velocity profile of given amplitude are stronger in cases of larger horizontal and smaller vertical scales. Such temperature anomalies become significant at planetary scales so that properly accounting for the horizontal momentum balance, including convective momentum transport (CMT), becomes necessary, while a weak temperature gradient approach that neglects horizontal momentum balance is no longer adequate. The downward advection component of the CMT in particular is important for capturing a number of features of the mock Walker cells. The extent of convective organization also affects the mock Walker cell through its effects on the sensitivities of convective heating and moistening to temperature and moisture anomalies. For strongly organized convection with deep inflows, these sensitivities are consistent with a layer mode of convective overturning, instead of the parcel mode as in unorganized convection, resulting in a weaker second baroclinic component in the mock Walker cells.

scholarly journals PRELIMINARY STUDY OF HORIZONTAL AND VERTICAL WIND PROFILE OF QUASI-LINEAR CONVECTIVE UTILIZING WEATHER RADAR OVER WESTERN JAVA REGION, INDONESIA

2019 ◽  
Vol 15 (2) ◽  
pp. 177
Author(s):  
Abdullah Ali ◽  
Riris Adrianto ◽  
Miming Saepudin
Keyword(s):  
Velocity Profile ◽  
Vertical Velocity ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Convective Cloud ◽  
Vertical Wind ◽  
Squall Line ◽  
Vertical Velocity Profile ◽  
Preliminary Study ◽  
Wind Profiles

One of the weather phenomena that potentially cause extreme weather conditions is the linear-shaped mesoscale convective systems, including squall lines. The phenomenon that can be categorized as a squall line is a convective cloud pair with the linear pattern of more than 100 km length and 6 hours lifetime. The new theory explained that the cloud system with the same morphology as squall line without longevity threshold. Such a cloud system is so-called Quasi-Linear Convective System (QLCS), which strongly influenced by the ambient dynamic processes, include horizontal and vertical wind profiles. This research is intended as a preliminary study for horizontal and vertical wind profiles of QLCS developed over the Western Java region utilizing Doppler weather radar. The following parameters were analyzed in this research, include direction pattern and spatial-temporal significance of wind speed, divergence profile, vertical wind shear (VWS) direction, and intensity profiles, and vertical velocity profile. The subjective and objective analysis was applied to explain the characteristics and effects of those parameters to the orientation of propagation, relative direction, and speed of the cloud system’s movement, and the lifetime of the system. Analysis results showed that the movement of the system was affected by wind direction and velocity patterns. The divergence profile combined with the vertical velocity profile represents the inflow which can supply water vapor for QLCS convective cloud cluster. Vertical wind shear that effect QLCS system is only its direction relative to the QLCS propagation, while the intensity didn’t have a significant effect.

scholarly journals Implications of the form of the Flow Law for Vertical Velocity and Age–Depth Profiles in Polar Ice

1986 ◽  
Vol 32 (112) ◽  
pp. 366-370 ◽  
Author(s):  
E.W. Wolff ◽  
C.S.M. Doake
Keyword(s):  
Velocity Profile ◽  
Depth Profile ◽  
Vertical Velocity ◽  
Experimental Error ◽  
Ice Sheet ◽  
Polar Ice ◽  
Depth Profiles ◽  
Devon Island ◽  
Vertical Velocity Profile ◽  
Flow Law

AbstractTwo situations are studied in relation to the flow law of polar ice. In each case, models are used with a flow-law exponent of one, and with the more traditional exponent of three. The horizontal velocity profile at Devon Island, Arctic Canada, is better fitted byn= 1; for the vertical velocity profile,n= 3 gives a better fit, but both model profiles fall well within experimental error. For the Camp Century age–depth profile, onlyn= 1 gives an acceptable fit when temperature is allowed for. The large discrepancy between isothermal and non-isothermal models forn= 3 shows the importance of allowing for temperature in studies of ice-sheet properties.

Study on the Two Patters of Vertical Velocity Profile of Tidal Current and Their Law in Estuary and Coastal Waters

2009 ◽  
Author(s):  
Zhihui Ni ◽  
Zhiyao Song
Keyword(s):  
Fractal Dimension ◽  
Velocity Profile ◽  
Vertical Velocity ◽  
Coastal Waters ◽  
Tidal Current ◽  
Surface Wind ◽  
Surface Flow ◽  
Sea Surface ◽  
Vertical Velocity Profile ◽  
Cubic Function

Many scholars at home and abroad have studied tidal velocity profile in estuarine and coastal waters. The results show that velocity profile of tidal current often deviated obviously from the traditional logarithmic profile, due to the flow including wind-driven current, wave-driven current, salinity and so on. In estuarine waters, runoff should be included as a component. In this paper, two patters of vertical velocity profile of tidal current are firstly divided, that are monotone increasing I-velocity profile (during flood tide and ebb tide stage) and non-monotone increasing II -velocity profile (during slack tide stage). Then, by use of variable fractal dimension to obtain the law of II-velocity profile, the results show that: (1)The II -velocity vertical profile does express a first-order accumulated variable-dimensional fractal phenomenon. (2) Through of the fractal dimension, the various formula fitting II-velocity profile were compared, and the results showed that, in practical applications of engineering, cubic function formula is the best fit as the measured data have been verified. Finally, the cubic function formula is applied to flow separation of II -velocity measured in Yangtze River. By the easily separation of the measured flow, we can not only get a reasonable surface flow velocity, such as wind-driven current, runoff, salinity, as well as their driving force weight in the hydrodynamic of estuarine and coastal waters, but also gain the data of bed roughness length and sea surface wind speed, providing reasonable border conditions of the seabed and sea surface for the hydrodynamic numerical simulation in estuarine and coastal waters.

Active layer slope movement in a continuous permafrost environment, Garry Island, Northwest Territories, Canada

1981 ◽  
Vol 18 (11) ◽  
pp. 1666-1680 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Velocity Profile ◽  
Active Layer ◽  
Vertical Velocity ◽  
Late Summer ◽  
Organic Layer ◽  
Field Investigations ◽  
Permafrost Environment ◽  
Vertical Velocity Profile ◽  
Ice Wedge ◽  
Ice Content

Field investigations have been carried out at Garry Island, N.W.T. for the 1964–1980 period in order to study downslope active layer movement at sites with two-sided (downward and upward) freezing and active ice-wedge growth. Movements have been determined with reference to semi-flexible plastic tubes inserted vertically into the ground and by deformation of lines of stakes. The results show that the vertical velocity profile on the hillslopes with clayey hummocks is convex downslope; the movement is plug-like and occurs in late summer; the plug-like movement progressively buries the interhummock peat to form a buried organic layer; and most of the plug-like movement can be attributed to frost creep by thaw of an ice-rich layer at the bottom of the active layer. The ice-rich layer forms by upfreezing in winter and the ice content may be augmented by ice lensing in the summer thaw period. In a sedgy drainage swale, the vertical velocity profile is concave downslope. The active layer of ice-wedge polygons shows a net movement outwards from the centres to the troughs. These studies show that active layer movement at sites with two-sided freezing and active ice-wedge polygons may differ substantially from sites with only one-sided freezing and without active ice-wedge polygons.

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