Role of roughness geometry function on spatially averaged form induced shear stresses and pressure energy diffusion rates in gravel-bed stream

2021 ◽  
pp. 1-12
Author(s):  
Mithun Ghosh ◽  
Pritam Malakar ◽  
Ratul Das
Keyword(s):  
Shear Stresses ◽  
Gravel Bed ◽  
Energy Diffusion ◽  
Diffusion Rates ◽  
Geometry Function

UNRAVELLING THE ROLE OF VEGETATION IN THE AVULSION HISTORY OF GRAVEL-BED RIVERS

2018 ◽  
Author(s):  
Daniel Donahue ◽  
◽  
José Antonio Constantine ◽  
Gregory B. Pasternack
Keyword(s):  
Gravel Bed ◽  
History Of ◽  
Gravel Bed Rivers

scholarly journals Water-Worked Gravel Bed: State-of-the-Art Review

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 694 ◽  
Author(s):  
Ellora Padhi ◽  
Subhasish Dey ◽  
Venkappayya R. Desai ◽  
Nadia Penna ◽  
Roberto Gaudio
Keyword(s):  
State Of The Art ◽  
Flow Characteristics ◽  
Streamwise Velocity ◽  
Secondary Currents ◽  
Gravel Bed ◽  
Natural Stream ◽  
Art Research ◽  
The Comparative Study ◽  
Water Work

In a natural gravel-bed stream, the bed that has an organized roughness structure created by the streamflow is called the water-worked gravel bed (WGB). Such a bed is entirely different from that created in a laboratory by depositing and spreading gravels in the experimental flume, called the screeded gravel bed (SGB). In this paper, a review on the state-of-the-art research on WGBs is presented, highlighting the role of water-work in determining the bed topographical structures and the turbulence characteristics in the flow. In doing so, various methods used to analyze the bed topographical structures are described. Besides, the effects of the water-work on the turbulent flow characteristics, such as streamwise velocity, Reynolds and form-induced stresses, conditional turbulent events and secondary currents in WGBs are discussed. Further, the results form WGBs and SGBs are compared critically. The comparative study infers that a WGB exhibits a higher roughness than an SGB. Consequently, the former has a higher magnitude of turbulence parameters than the latter. Finally, as a future scope of research, laboratory experiments should be conducted in WGBs rather than in SGBs to have an appropriate representation of the flow field close to a natural stream.

scholarly journals The Role of Energy Diffusion in the Deposition of Energetic Electron Energy in Solar and Stellar Flares

2019 ◽  
Vol 880 (2) ◽  
pp. 136 ◽  
Author(s):  
Natasha L. S. Jeffrey ◽  
Eduard P. Kontar ◽  
Lyndsay Fletcher
Keyword(s):  
Electron Energy ◽  
Energetic Electron ◽  
Energy Diffusion ◽  
Stellar Flares

Stiffness of the pleural surface of the chest wall is similar to that of the lung

2003 ◽  
Vol 95 (6) ◽  
pp. 2345-2349 ◽  
Author(s):  
Andrew Gouldstone ◽  
Richard E. Brown ◽  
James P. Butler ◽  
Stephen H. Loring
Keyword(s):  
Chest Wall ◽  
Elastohydrodynamic Lubrication ◽  
Geometric Standard Deviation ◽  
Parietal Pleura ◽  
Shear Stresses ◽  
Membrane Tension ◽  
Similar Extent ◽  
Spatial Uniformity ◽  
Pleural Surface

To address the role of the parietal pleura in reduction of mesothelial shear stresses during breathing, we measured the stiffness of the parietal pleural surface of mammalian chest walls using microindentation. The pleural surface was indented over ribs and intercostal spaces with rigid flat punches (tip radii of 0.01, 0.02, and 0.1 cm) to probe stiffness at length scales comparable with those of surface asperities. We found a tissue shear modulus of 6,700 dyn/cm2 and pleural membrane tension of 4,900 dyn/cm, with a geometric standard deviation of 0.42. These values are similar to those measured for the lung by Hajji et al., using indentation (Hajji MA, Wilson TA, and Lai-Fook SJ. J Appl Physiol Respirat Environ Exerc Physiol 47: 175–181, 1979). Surprisingly, the pleural surface over ribs and intercostal spaces exhibited similar stiffness. In addition, caudal regions exhibited lower stiffness than cranial regions. In the context of elastohydrodynamic lubrication, these results suggest that shear-induced pressures during breathing deform the chest wall and lung surfaces to a similar extent, promoting spatial uniformity of pleural fluid thickness and reducing shear stresses.

Benzene, Toluene, and Xylene Transport through UiO-66: Diffusion Rates, Energetics, and the Role of Hydrogen Bonding

2018 ◽  
Vol 122 (28) ◽  
pp. 16060-16069 ◽  
Author(s):  
Tyler G. Grissom ◽  
Conor H. Sharp ◽  
Pavel M. Usov ◽  
Diego Troya ◽  
Amanda J. Morris ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Benzene Toluene ◽  
Diffusion Rates

Recent developments in modeling ice sheet deformation

2020 ◽  
Author(s):  
Felicity McCormack ◽  
Roland Warner ◽  
Adam Treverrow ◽  
Helene Seroussi
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Vertical Shear ◽  
Shear Stresses ◽  
Polar Ice ◽  
Ice Flow ◽  
Polar Ice Sheets ◽  
Basal Shear ◽  
The Impact

<p>Viscous deformation is the main process controlling ice flow in ice shelves and in slow-moving regions of polar ice sheets where ice is frozen to the bed. However, the role of deformation in flow in ice streams and fast-flowing regions is typically poorly represented in ice sheet models due to a major limitation in the current standard flow relation used in most large-scale ice sheet models – the Glen flow relation – which does not capture the steady-state flow of anisotropic ice that prevails in polar ice sheets. Here, we highlight recent advances in modeling deformation in the Ice Sheet System Model using the ESTAR (empirical, scalar, tertiary, anisotropic regime) flow relation – a new description of deformation that takes into account the impact of different types of stresses on the deformation rate. We contrast the influence of the ESTAR and Glen flow relations on the role of deformation in the dynamics of Thwaites Glacier, West Antarctica, using diagnostic simulations. We find key differences in: (1) the slow-flowing interior of the catchment where the unenhanced Glen flow relation simulates unphysical basal sliding; (2) over the floating Thwaites Glacier Tongue where the ESTAR flow relation outperforms the Glen flow relation in accounting for tertiary creep and the spatial differences in deformation rates inherent to ice anisotropy; and (3) in the grounded region within 80km of the grounding line where the ESTAR flow relation locally predicts up to three times more vertical shear deformation than the unenhanced Glen flow relation, from a combination of enhanced vertical shear flow and differences in the distribution of basal shear stresses. More broadly on grounded ice, the membrane stresses are found to play a key role in the patterns in basal shear stresses and the balance between basal shear stresses and gravitational forces simulated by each of the ESTAR and Glen flow relations. Our results have implications for the suitability of ice flow relations used to constrain uncertainty in reconstructions and projections of global sea levels, warranting further investigation into using the ESTAR flow relation in transient simulations of glacier and ice sheet dynamics. We conclude by discussing how geophysical data might be used to provide insight into the relationship between ice flow processes as captured by the ESTAR flow relation and ice fabric anisotropy.</p>

New Interpretation of the Influence of Various Parameters on Texture Evolution in Damascene Cu Interconnect Lines

2005 ◽  
Vol 495-497 ◽  
pp. 1449-1454 ◽  
Author(s):  
Kabir Kumar Mirpuri ◽  
Jerzy A. Szpunar
Keyword(s):  
Dislocation Density ◽  
Texture Evolution ◽  
Shear Stresses ◽  
Principal Stresses ◽  
Line Spacing ◽  
Role Of Principal ◽  
New Interpretation ◽  
Cu Interconnect ◽  
Interconnect Lines

The article takes into account various factors which effect the texture evolution in the Cu lines. We propose here an explanation for the formation of {111}<110> and {111}<112> texture in the Cu lines. The explicit role of principal stresses, shear stresses and dislocations is discussed. The influence of line spacing on strength of the {111}<110> and {111}<112> texture components is also demonstrated in relation to the dislocation density.

A Computer Simulation of the Blood Flow at the Aortic Bifurcation With Flexible Walls

1993 ◽  
Vol 115 (3) ◽  
pp. 306-315 ◽  
Author(s):  
Zheng Lou ◽  
Wen-Jei Yang
Keyword(s):  
Blood Flow ◽  
Moving Boundary ◽  
Shear Stresses ◽  
Arbitrary Lagrangian Eulerian ◽  
Aortic Bifurcation ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Flexible Walls ◽  
Linear Viscoelastic ◽  
Flow Reversals

To understand the role of fluid dynamics in atherogenesis, especially the effect of the flexibility of arteries, a two-dimensional numerical model for blood flow at the aortic bifurcation with linear viscoelastic walls is developed. The arbitrary Lagrangian-Eulerian method is adopted to deal with the moving boundary problem. The wall expansion induces flow reversals or eddies during the decelerating systole while the wall contraction restricts them during the diastole. A flexible bifurcation experiences the shear stresses about 10 percent lower than those of a rigid one.

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