Performance of lateral velocity distribution models for compound channel sections

2004 ◽  
pp. 449-457 ◽  
Author(s):  
J Weber ◽  
A Menéndez
Keyword(s):  
Velocity Distribution ◽  
Compound Channel ◽  
Distribution Models ◽  
Lateral Velocity

Lateral velocity distribution in open channels with partially flexible submerged vegetation

2016 ◽  
Vol 16 (6) ◽  
pp. 1267-1282 ◽  
Author(s):  
Lijuan Han ◽  
Yuhong Zeng ◽  
Li Chen ◽  
Wenxin Huai
Keyword(s):  
Velocity Distribution ◽  
Open Channels ◽  
Submerged Vegetation ◽  
Lateral Velocity

The velocity distribution function within a shock wave

1967 ◽  
Vol 30 (3) ◽  
pp. 479-487 ◽  
Author(s):  
G. A. Bird
Keyword(s):  
Shock Wave ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Numerical Experiments ◽  
Equilibrium Distribution ◽  
Velocity Distribution Function ◽  
Distribution Functions ◽  
Rigid Sphere ◽  
Lateral Velocity ◽  
Shock Profile

The structure of normal shock waves in a gas composed of rigid sphere molecules is investigated by numerical experiments with a simulated gas on a digital computer. The non-equilibrium between the temperatures based on the longitudinal and lateral velocity components is studied and the results compared with the theory of Yen (1966). Details of the velocity distribution function are presented for a shock of Mach number 10. The distribution functions for both the longitudinal and lateral velocity components are plotted for a number of locations in the shock profile and are compared with the equilibrium distribution.

The Preliminary Study on Comparison of Velocity Distribution Models Under the Same Roughness Length

2006 ◽  
Author(s):  
Jialing Hao ◽  
Yixin Yan ◽  
Zhiyao Song ◽  
Changnan Wang
Keyword(s):  
Velocity Profile ◽  
Velocity Distribution ◽  
Linear Model ◽  
Tidal Cycle ◽  
Roughness Length ◽  
Distribution Model ◽  
Surface Boundary ◽  
Distribution Models ◽  
Logarithmic Model ◽  
Log Linear

Previous studies pointed out that due to the acceleration or deceleration action of tide current, the flow structure deviates from traditional logarithmic law in estuary, coast or other near shore water. The tidal velocity distribution model was derived and compared with the traditional logarithmic model. It should be pointed out that the velocity data adopted have four layers within one meter above the bed, and the roughness length z0 is different in the two models even in the same velocity profile. Because the fluctuation of roughness length z0 is remarkable when determining by single velocity profile, some studies thought that the variation of roughness length was small between adjacent time when the change of topography was less obviously. Therefore, the measured data is divided into several sections by one day or a tidal cycle to fit the velocity profile of every section to obtain a roughness length z0, i.e., the roughness length z0 varies only after a day or a tidal cycle. The purpose of the paper is to expand the log-linear model to full depth by adding the surface boundary condition ∂u∂zz=D=0(Diswaterdepth) and to discuss the difference when 6 points (bottom layer, 0.2D, 0.4D, 0.6D, 0.8D, surface layer) velocity profile are fitted by logarithmic model, log-linear model, and extended log-linear model with the same roughness length z0 in different time section, respectively. The calculated friction velocity and friction coefficient and their correlation are discussed. The results show that the log-linear model and the log-linear extend model are closer to the measure velocity profile than that of the logarithmic model.

scholarly journals Sensitivities of Bottom Stress Estimation to Sediment Stratification in a Tidal Coastal Bottom Boundary Layer

2020 ◽  
Vol 8 (4) ◽  
pp. 256
Author(s):  
Yun Peng ◽  
Qian Yu ◽  
Yunwei Wang ◽  
Qingguang Zhu ◽  
Ya Ping Wang
Keyword(s):  
Velocity Distribution ◽  
Critical Role ◽  
Sediment Concentration ◽  
Distribution Models ◽  
Bottom Boundary ◽  
Field Investigations ◽  
Bottom Boundary Layers ◽  
Direct Covariance ◽  
Stress Estimation ◽  
Sediment Stratification

The bottom friction velocity (U*), which controls seabed erosion and deposition, plays a critical role in sediment transport in tidal coastal bottom boundary layers. Approaches have been proposed to calculate U*, including the log profile (LP) estimation, the direct covariance (COV) measurement, and the turbulent kinetic energy (TKE) method. However, the LP method assumes homogeneous flow and the effects of stratification need to be taken into account. Here, field investigations of hydrodynamics and sediment dynamics were carried out on the Jiangsu Coast, China. Two acoustic Doppler velocimeters (ADV) velocity measurements at 0.2 and 1 m above the seabed have been used to estimate U*, based on the aforementioned three methods. The COV and TKE methods provided reasonable estimations of U*, while a pronounced overestimation was identified when using the LP method. This overestimation can be attributed to the stratification effects associated with the vertical suspended sediment concentration (SSC) gradient near the bottom. Then, three models were utilized to correct the overestimation, in which the gradient/flux Richardson number was modified with empirical constants α, β, and A to parameterize the stratification effects in the logarithmic velocity distribution. The values of α, β, and A derived from the observation are smaller than the results from previous investigations. These modified logarithmic velocity distribution models can be applied in numerical simulations when sediment stratification is important.

scholarly journals Study on the Horizontal Distribution Law of Flood Water and Sediment Factors under the Effect of Vegetation on a Curved Beach

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1441
Author(s):  
Mingwu Zhang ◽  
Pan Li ◽  
Xiaoping Li ◽  
Aoxue Wang ◽  
Zhenhai Wang ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Model Test ◽  
Main Channel ◽  
Theoretical Research ◽  
Distribution Model ◽  
Main Stream ◽  
Compound Channel ◽  
Transverse Distribution ◽  
Water And Sediment ◽  
Beach Vegetation

The sediment-laden floodplain flood is affected by beach vegetation and the shape of curved compound channels. The laws of water and sediment exchange and deposition distribution in beach troughs are very complex and play a significant role in the formation and development of secondary suspended rivers, the adjustment of beach horizontal gradients, and even the evolution of flood control situations. This study used a combination of experimental simulations and theoretical research to carry out a generalized model test of floodplain flood evolution, analyzing the transverse distribution characteristics of sediment-laden flow and sediment factors in a curved compound channel under the conditions of beach vegetation, proposing a theoretical model of transverse distribution of velocity and sediment concentration that is based on the momentum equation considering the inertial force of the lateral secondary flow and river curvature. The results showed the following: (1) The model test results for floodplain flood in the compound channel with curved vegetation showed that the main stream was not only concentrated in the main channel but also appeared near the foot of the left and right bank levees and formed flood discharge along the embankment, as the beach siltation was mainly concentrated in the beach lip; (2) The arrangement of full vegetation on the beach had a uniform effect on the velocity distribution of the beach, which can reduce the phenomenon of excessive velocity at the foot of the beach and increase the velocity effect in the main channel; and (3) Through five numerical examples, the lateral velocity distribution model of a curved compound channel with beach vegetation was tested and, in general, the analysis model was consistent with the experimental results. The research results will provide a theoretical basis for river management and have great significance for enriching the basic theory of water and sediment movement and promoting the integration of hydraulics, river dynamics, and ecology.

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