The granular monoclinal wave

2018 ◽  
Vol 843 ◽  
pp. 810-846 ◽  
Author(s):  
Dimitrios Razis ◽  
Giorgos Kanellopoulos ◽  
Ko van der Weele
Keyword(s):  
Uniform Flow ◽  
Shear Stresses ◽  
Friction Law ◽  
System Parameters ◽  
Chute Flow ◽  
Thick Region ◽  
Balance Of Forces

We study granular chute flow using the classic Saint-Venant approach, with the shear stresses within the granular sheet being incorporated via a friction law due to Pouliquen & Forterre (J. Fluid Mech., vol. 453, 2002, pp. 113–151) and with the in-plane stresses (which are ignored in the traditional formulation for normal fluids) being represented by a viscous-like term recently derived by Gray & Edwards (J. Fluid Mech., vol. 755, 2014, pp. 503–534). On the basis of this model, we predict that the granular sheet is able to sustain monoclinal waves, i.e. travelling shock structures that monotonically connect a thick region of uniform flow to a thinner one. We examine the balance of forces that determine the shape of this particular waveform and give the precise window of system parameters for which monoclinal waves are expected to appear in experiments.

A dynamical systems view of granular flow: from monoclinal flood waves to roll waves

2019 ◽  
Vol 869 ◽  
pp. 143-181
Author(s):  
Dimitrios Razis ◽  
Giorgos Kanellopoulos ◽  
Ko van der Weele
Keyword(s):  
Granular Flow ◽  
Granular Matter ◽  
Uniform Flow ◽  
Constant Thickness ◽  
Undular Bore ◽  
Formula One ◽  
Chute Flow ◽  
Roll Waves ◽  
Saint Venant Equations ◽  
Systems View

On the basis of the Saint-Venant equations for flowing granular matter, we study the various travelling waveforms that are encountered in chute flow for growing Froude number. Generally, for $Fr<2/3$ one finds either a uniform flow of constant thickness or a monoclinal flood wave, i.e. a shock structure monotonically connecting a thick region upstream to a shallower region downstream. For $Fr>2/3$ both the uniform flow and the monoclinal wave cease to be stable; the flow now organizes itself in the form of a train of roll waves. From the governing Saint-Venant equations we derive a dynamical system that elucidates the transition from monoclinal waves to roll waves. It is found that this transition involves several intermediate stages, including an undular bore that had hitherto not been reported for granular flows.

scholarly journals DISSIPATION OF WAVE ENERGY DUE TO OPPOSING CURRENT

1972 ◽  
Vol 1 (13) ◽  
pp. 30
Author(s):  
Toshio Iwasaki ◽  
Michio Sato
Keyword(s):  
Energy Dissipation ◽  
Surface Waves ◽  
Wave Height ◽  
Wave Energy ◽  
Uniform Flow ◽  
Shear Stresses ◽  
Flow Energy ◽  
Boundary Shear ◽  
Wave Height Attenuation

Energy dissipation and wave height attenuation were analysed theoretically for surface waves propagating against uniform flow. Energy dissipation was estimated from evaluation of work "by internal and boundary shear stresses. Experiments were conducted in a test flume of 20m long, 0.8m wide and 0.5m high. Results showed that tested values of rate of wave height attenuation were comparable with theoretical values.

The contact and friction problem in the rolling process

2000 ◽  
Vol 214 (1) ◽  
pp. 61-69
Author(s):  
J D Lee ◽  
S Shen
Keyword(s):  
Finite Element ◽  
Virtual Work ◽  
Large Strain ◽  
Three Dimensional ◽  
Rolling Process ◽  
Shear Stresses ◽  
Time Step ◽  
Element Analysis ◽  
Friction Law ◽  
Updated Lagrangian

In this work, a new generalized non-Euclidean friction law is proposed. This friction law allows the friction coefficients in the tangential and axial directions of the roll to be different. A three-dimensional, large-strain, non-steady state elastic-plastic finite element analysis has been performed for the flat rolling process. The contact and friction problem at the interface between the workpiece and the rolls is treated rigorously. The finite element procedures are based on the updated Lagrangian virtual work equations in incremental form. The solution at each time step is accepted only if the equilibrium of nodal forces, the calculation of which is an exact treatment, is reached pointwise. The numerical results, including the interfacial normal and shear stresses, are presented and discussed.

scholarly journals Analytical solution of non-uniform flow in compound channel

2018 ◽  
Vol 40 ◽  
pp. 06041 ◽  
Author(s):  
Kamalini Devi ◽  
Bhabani S. Das ◽  
Jnana R. Khuntia ◽  
Kishanjit K. Khatua
Keyword(s):  
Analytical Solution ◽  
Flow Behavior ◽  
Uniform Flow ◽  
Shear Stresses ◽  
Data Sets ◽  
Compound Channels ◽  
Effective Stresses ◽  
Boundary Shear ◽  
Flow Variables ◽  
Boundary Shear Stress

The present work investigates the analysis of depth-averaged velocity and boundary shear stress distribution in compound channels with non-uniform flow condition. A quasi two-dimensional model is proposed to assess the flow variables by accounting the physical processes that are specific to non-uniform flow. For analyzing the flow behavior, experimental data sets concerning compound channels with narrowing and enlarging floodplains of previous investigators are considered. The model accounts the influence of momentum transfer on the flow variables through additional shear stresses that are developed in non-uniform flow. Three types of effective stresses produced by molecular viscosity, turbulent and dispersion on the vertical planes are discussed. An analytical solution to the model is presented. Terms associated with the effective stresses are investigated relating them to the geometric and hydraulic parameters. The significance of lateral variation of energy slope is further investigated. For both homogenous and heterogeneous non-prismatic channels, the approach is examined to predict the flow variables with reasonable accuracy.

Naturalization of Drainage Channels in Lithuania and Possibilities of Their Maintenance as Water Recipients

2003 ◽  
Vol 34 (5) ◽  
pp. 493-506 ◽  
Author(s):  
Alfonsas Rimkus ◽  
Romanas Lamsodis ◽  
Saulius Vaikasas
Keyword(s):  
Water Movement ◽  
Background Level ◽  
Positive Influence ◽  
Hydraulic Calculation ◽  
Shear Stresses ◽  
Study Results ◽  
Drainage Channels ◽  
Land Cultivation ◽  
Channel Maintenance ◽  
Balance Of Forces

In the process of high expansion of drainage systems and land cultivation, most natural watercourses in Lithuania were converted into drainage channels. They were deprived of all natural riparian vegetation and abiotic conditions that kept up biodiversity, diminished erosion and deflation, induced self-purification of water etc. Thus the re-naturalization of drainage channels is essential. Consequently, to determine the possibilities to combine re-naturalization processes in channels with their function-ability it was examined the tendencies of woody vegetation (WV) spreading and the hydraulic calculation formulas estimating the performance of overgrown channels as water recipients were suggested. As the study results showed, self-restoration of WV was most progressive in forest and outskirt channels. In the field channels WV expansion takes place as well. However, it depends on the distance from a forest, i.e. WV density decreases sharply from 1.17 stems m−2 to background level (c. 0.26 stems m−2) within the space of 300 m. In the paper there is some positive influence of WV cover in view to drainage channel maintenance discussed referring to the results of former studies as well as the publications of other authors. It includes the prevention of bottom silting as well as slope erosion and slide. The formulas estimating conductivity of overgrown channels are based on the balance of forces occurring on the boundaries of overgrown strips of a stream: resistance of tree stems, friction on the slopes, shear stresses that appear when two streams with different velocities are in contact and the horizontal component of the gravity force causing water movement. Some methods of WV cover abundance control are discussed when having assumed self- or artificial restoration of WV in channels to be maintained as recipients is projected.

Models of Cataclysmic Variables from Photometric and Spectroscopic Data

1979 ◽  
Vol 46 ◽  
pp. 65-74 ◽  
Author(s):  
A.C. Fabian ◽  
J.E. Pringle ◽  
J.A.J. Whelan ◽  
J.A. Bailey
Keyword(s):  
Spectroscopic Data ◽  
Cataclysmic Variables ◽  
System Parameters ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

Abstract.Recent photometric and spectroscopic observations of the dwarf nova system Z Cha are discussed. Methods for constraining the system parameters are applied and the disc emissivity is deduced as a function of radius. Indications are found that the disc shrinks in size with increasing time after outburst.

Some Factors Influencing Metabolism and Distribution of Fibrinogen in Man and Rabbits

1977 ◽  
Vol 37 (02) ◽  
pp. 243-252
Author(s):  
Yi-Hsiang Chen ◽  
E. B Reeve
Keyword(s):  
Plasma Fibrinogen ◽  
Synthesis Rate ◽  
Fibrinogen Concentration ◽  
Fractional Catabolic Rate ◽  
System Parameters ◽  
Catabolic Rate ◽  
Simultaneous Decrease ◽  
Normal Males ◽  
Healthy Females ◽  
Made In

SummaryTo shed some light on the homeostatic regulation of plasma fibrinogen, metabolic studies were made in healthy females, and in normal, thyroidectomized, and thyroxine-treated rabbits. In females, compared with normal males, plasma fibrinogen concentration, plasma and interstitial fibrinogen decreased consequent to an increased fractional catabolic rate and a normal fibrinogen synthesis rate. The interstitial/plasma fibrinogen ratio remained unchanged. In normal rabbits, with increasing body weight fractional catabolic rate and catabolic rate decreased, while fibrinogen concentration and plasma fibrinogen remained constant owing to a simultaneous decrease in fibrinogen synthesis. In addition, fractional transcapillary transfer rate and transcapillary flux also decreased resulting in a shrinkage of interstitial fibrinogen. Thyroidectomy and thyroxine-injection markedly altered fibrinogen metabolism: thyroid hormone accelerated fibrinogen catabolism but also stimulated synthesis. The net result was an increase in plasma fibrinogen and fibrinogen concentration. The interstitial/plasma fibrinogen ratio decreased in thyroxine-treated, and increased in thyroidectomized animals. This study defines the variations of the fibrinogen system parameters in these physiologic and pathologic conditions, and illustrates some patterns of alterations in fibrinogen metabolism.

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