نتایج جستجو برای: bed roughness

تعداد نتایج: 70522  

2008
Chiang C. Mei

Unlike a transonic flow in compressible aerodynamics, a ship cruising steadily in a channel at nearly the linearized long wave speed generates unsteady wave motion. In a channel of limited width, solitons are radiated periodically up-stream. Such waves may have been the cause of a fatal accident at the Port of Harwich, England, and were described by a witness “like the white cliffs of Dover”. A...

Soil and water resources management of rivers has an important role because of direct relation withdifferent systems such as earth, life, social and people. Although the use of vegetation cover inbioengineering and biological stabilization and also soil and water resources management projects hasmany advantages, but improper methods of design and implementation cause hydraulic specificationsof ...

Journal: :Tikrit Journal of Engineering Science 2022

One of the significant problems facing water resource engineer is calculating coefficient roughness for subsequent design calculations discharge amount a channel or river. In this study, experiments were conducted in semi-circular, straight to investigate factors affecting bed and flow using Artificial Neural Network (ANN). For purpose, three semi-circular models with free overfall constructed ...

Journal: :Journal of Glaciology 2021

Abstract During the last few decades, bed-elevation profiles from radar sounders have been used to quantify bed roughness. Various methods employed, such as ‘two-parameter’ technique that considers vertical and slope irregularities in topography, but they struggle incorporate roughness at multiple spatial scales leading a breakdown their depiction of where relief is most complex. In this articl...

Journal: :Remote Sensing 2015
Xin Tian Christiaan van der Tol Zhongbo Su Zengyuan Li Erxue Chen Xin Li Min Yan Xuelong Chen Xufeng Wang Xiaoduo Pan Feilong Ling Chunmei Li Wenwu Fan Longhui Li

We propose a long-term parameterization scheme for two critical parameters, zero-plane displacement height (d) and aerodynamic roughness length (z0m), that we further use in the Surface Energy Balance System (SEBS). A sensitivity analysis of SEBS indicated that these two parameters largely impact the estimated sensible heat and latent heat fluxes. First, we calibrated regression relationships b...

2000
Cheng-I Hsieh Gabriel Katul

An approximate analytical model was developed to estimate scalar ̄ux footprint in thermally strati®ed atmospheric surface layer ̄ows. The proposed model was based on a combination of Lagrangian stochastic dispersion model results and dimensional analysis. The main advantage of this model is its ability to analytically relate atmospheric stability, measurement height, and surface roughness length...

2007
Junke Guo Pierre Y. Julien

The modified log-wake law, which was developed for turbulent boundary layers and pipe flows, is extended to turbulent flows in open-channels. Turbulent velocity profiles in open-channels can be approximated with three components: (1) the law of the wall that results from the constant bed shear stress; (2) the law of the wake that reflects the effects of gravity, secondary currents and bed rough...

Present study examines turbulent structures of a rough bed open-channel flow in the context of deterministic approach. Instantaneous velocity field is measured in different hydraulic conditions using two dimensional Particle Image Velocimetry (PIV) in vertical plane and Stereoscopic PIV in horizontal plane. Different techniques and quantities such as swirl strength, two-point and cross-correlat...

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