نتایج جستجو برای: coefficient roughness

تعداد نتایج: 189794  

2008
Tamay M. Özgökmen Paul F. Fischer

Overflows play an important role in the downwelling limb of the oceanic thermohaline circulation. In light of the recognition that some overflows are not homogenous but exhibit a vertical density structure, and details of topography influence the pathways of some overflows, the impact of topographic roughness on the product property distribution is explored using the 3D non-hydrostatic spectral...

2012
L. Bennaceur Farah I. R. Farah R. Bennaceur Z. Belhadj M. R. Boussema

The overall objective of this paper is to retrieve soil surfaces parameters namely, roughness and soil moisture related to the dielectric constant by inverting the radar backscattered signal from natural soil surfaces. Because the classical description of roughness using statistical parameters like the correlation length doesn't lead to satisfactory results to predict radar backscattering, we u...

2017
M. Niazkar N. Talebbeydokhti S. H. Afzali

Although Darcy-Weisbach (D-W) equation has been accepted as a standard resistance equation in pressurized flow, some researchers and engineers still prefer to utilize Hazen-Williams (H-W) equation for analyzing water distribution networks (WDNs) in practice. The main difference between roughness coefficients of these two resistance equations is that D-W friction factor varies with Reynolds numb...

2010
Seung-Bum Kim Eni G. Njoku

A time-series algorithm is proposed to retrieve surface (from surface down to 1 m depth) soil moisture using the simulated radar data. The time-series approach uses co-polarized (V V and HH) backscattering coefficient (σ) values. Temporal averaging is applied to reduce the radar measurement noise. To the extent that the surface roughness does not change within the time-series window, the reduct...

ژورنال: علوم آب و خاک 2009
بونر, کریستینا, قضاوی, غلامرضا, قوی, استفان, میرزایی, محمدرضا,

At present, soil surface characteristics (SSC) are recognised as key parameters controlling infiltration rates, runoff generation and erosion. Microtopography of surface among SSC is the main one. The work presented in this paper is based on a set of digital elevation models (DEMs) supplied by two different methods: Laser roughness-meter and photogrammetry method. We used two maquettes. The use...

The study of flow and heat transfer over rotating circular disks is of great practical importance in understanding the cooling of rotatory machinery such as turbines, electric motors and design and manufacturing of computer disk drives. This paper presents an analysis of the flow and heat transfer over a heated infinite permeable rough disk. Boundary-layer approximation reduces the elliptic Nav...

2008
A. S. Antonarakis K. S. Richards J. Brasington M. Bithell E. Muller

[1] Hydraulic resistance of riparian forests is an unknown but important term in flood conveyance modeling. Lidar has proven to be a very important new data source to physically characterize floodplain vegetation. This research outlines a recent campaign that aims to retrieve vegetation fluid resistance terms from airborne laser scanning to parameterize trunk roughness. Information on crown cha...

2014
Raúl López Javier Barragán

The relation between the equivalent roughness and different grain size percentiles of the sediment in gravel-bed rivers was determined under the hypothesis that the vertical distribution of the flow velocity follows a logarithmic law. A set of 954 data points was selected from rivers with gravel size sediment or larger, with a non-sinuous alignment and free of vegetation or obstacles. According...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
Dong Woog Lee Xavier Banquy Jacob N Israelachvili

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed re...

2013
Mohsen Zayernouri Sang-Woo Park Daniel M. Tartakovsky

We present an efficient computational method to model fluid flow in the presence of random wall roughness. A random flow domain is represented by a stochastic indicator function having a smoothed profile perpendicular to roughness, and the random domain is discretized with a fixed non-conformal grid. This procedure introduces a stochastic force into the Navier–Stokes equations, and modifies the...

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