scholarly journals Flow Over Embankment Gabion Weirs in Free Flow Conditions

2021 ◽  
Author(s):  
Roya Biabani ◽  
Farzin Salmasi ◽  
Meysam Nouri ◽  
John Abraham
Keyword(s):  
Energy Dissipation ◽  
Three Dimensional ◽  
Relative Energy ◽  
Physical Models ◽  
Flow Conditions ◽  
Environmental Aspects ◽  
Discharge Coefficients ◽  
Filling Materials ◽  
Surface Profiles ◽  
Crest Length

Abstract Gabion weirs have been widely used in rivers restoration and diversion water projects because of their hydro-environmental aspects and eco-friendly features. In this study, a series of laboratory tests were performed to investigate the effects of side ramp slope, crest length, and porous media properties on the flow regimes, water-surface profiles, discharge coefficients, and energy dissipation in embankment gabion weirs with upstream and downstream slopes. 24 physical models of solid and gabion weirs with three different upstream/downstream slopes (90°, 45° and 26.5°) were created. For gabion weirs, three different filling materials were tested. To investigate the complexity of flow over the porous-fluid interface and through the porous material, three-dimensional (3D) numerical simulations were developed. The results show that decreasing upstream slopes, from 90º to 26.5º, leads to decreased discharge coefficients. However, in all cases, gabion weirs lead to greater discharge coefficients than those of similar solid weirs. For milder side slopes, discharge ratios passing through all faces of the gabion weirs decreased nonlinearly. Moreover, with increasing the inlet discharge, relative energy dissipation was reduced up to 45% in gabion weirs.

scholarly journals Three-dimensional numerical investigation of flow through screens as energy dissipators

2017 ◽  
Vol 44 (10) ◽  
pp. 850-859 ◽  
Author(s):  
Rasoul Daneshfaraz ◽  
Sina Sadeghfam ◽  
Ali Ghahramanzadeh
Keyword(s):  
Energy Dissipation ◽  
Three Dimensional ◽  
Hydraulic Structures ◽  
Proof Of Concept ◽  
Flow Equations ◽  
Local Complex ◽  
Energy Dissipators ◽  
Flow Through ◽  
Surface Profiles ◽  
Supercritical Flows

Screens, perforated units to dissipate energy in hydraulic structures, are investigated numerically in this study. These units are part of a physical setup exposed to supercritical flows, normally created by sluice gates. The interaction of perforated screens and supercritical flows results in local complex three-dimensional flows, which can be analyzed by the application of RANS-based flow equations. The most important controlling parameters include supercritical Froude number between 2 and 10 and screen porosity of 40% and 50%. Numerical water surface profiles and energy dissipation are validated by the author’s experimental data. This paper derives a set of equations in terms of depth ratio of the hydraulic jump through the perforated screens and assesses the effect of baffles on energy dissipation. This study seeks a proof-of-concept for the application of the RANS-based technique for further application of the result to real hydraulic structures in due course.

scholarly journals Three-Dimensional Investigation of Hydraulic Properties of Vertical Drop in the Presence of Step and Grid Dissipators

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 895
Author(s):  
Rasoul Daneshfaraz ◽  
Ehsan Aminvash ◽  
Amir Ghaderi ◽  
Alban Kuriqi ◽  
John Abraham
Keyword(s):  
Energy Dissipation ◽  
Laboratory Data ◽  
Three Dimensional ◽  
Relative Energy ◽  
Relative Depth ◽  
Pool Depth ◽  
Drainage Channels ◽  
Simultaneous Use ◽  
Fully Coupled ◽  
Irrigation And Drainage Channels

In irrigation and drainage channels, vertical drops are generally used to transfer water from a higher elevation to a lower level. Downstream of these structures, measures are taken to prevent the destruction of the channel bed by the flow and reduce its destructive kinetic energy. In this study, the effect of use steps and grid dissipators on hydraulic characteristics regarding flow pattern, relative downstream depth, relative pool depth, and energy dissipation of a vertical drop was investigated by numerical simulation following the symmetry law. Two relative step heights and two grid dissipator cell sizes were used. The hydraulic model describes fully coupled three-dimensional flow with axial symmetry. For the simulation, critical depths ranging from 0.24 to 0.5 were considered. Values of low relative depth obtained from the numerical results are in satisfactory agreement with the laboratory data. The simultaneous use of step and grid dissipators increases the relative energy dissipation compared to a simple vertical drop and a vertical drop equipped with steps. By using the grid dissipators and the steps downstream of the vertical drop, the relative pool depth increases. Changing the pore size of the grid dissipators does not affect the relative depth of the pool. The simultaneous use of steps and grid dissipators reduces the downstream Froude number of the vertical drop from 3.83–5.20 to 1.46–2.00.

scholarly journals Three-Dimension Numerical Simulation of Scour Temporal Changes due to Flow in the Downstream of Combined Weirs and Gate Model

2017 ◽  
Vol 3 (11) ◽  
pp. 1111 ◽  
Author(s):  
Yaser Sadeghi Googheri ◽  
Mojtaba Saneie ◽  
Sirous Ershadi
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Turbulent Energy ◽  
Temporal Changes ◽  
Three Dimension ◽  
Flow Conditions ◽  
Scour Hole ◽  
Static Water

Most of weirs create a region with relatively static water in upstream, which can be the place of sediments and wastes deposition in water. Sediments accumulation in upstream changes flow conditions.  In this case, combined weir and gate can be propounded as a useful solution. In the present paper, Flow3D was used to numerically simulate temporal changes of scour in combined free flow over weirs and below gates. Numerical modeling was run after fully preparing and the obtained data was analyzed under three-dimensional conditions. Comparing experimental and numerical results with data fitness revealed that determination coefficient (R2) of the numerical model results to the experimental model results is 0.94. Also, it was found that the relative error of the numerical model results relative to the experimental results equals 7.36%. Further, it was found that at the start of computations in the numerical model, compared to the end of running the model, the turbulent energy dissipation was decreased to 38% and decreasing the turbulent energy dissipation led to the creation of scour hole balance in the numerical model.

Influence of Cartilaginous Matrix Accumulation on Viscoelastic Response of Chondrocyte/Agarose Constructs Under Dynamic Compressive and Shear Loading

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Shogo Miyata ◽  
Tetsuya Tateishi ◽  
Takashi Ushida
Keyword(s):  
Energy Dissipation ◽  
Biochemical Composition ◽  
Dynamic Compression ◽  
Three Dimensional ◽  
Shear Stiffness ◽  
Relative Energy ◽  
Shear Loading ◽  
Cartilage Defects ◽  
Sgag Content ◽  
Matrix Accumulation

A method has been developed to restore cartilage defects by culturing autologous chondrocytes to create a three dimensional tissue and then implanting the cultured tissue. In this kind of approach, it is important to characterize the dynamic mechanical behavior of the regenerated cartilaginous tissue, because these tissues need to bear various dynamic loadings in daily life. The objectives of this study were to evaluate in detail the dynamic viscoelastic responses of chondrocyte-seeded agarose gel cultures in compression and torsion (shear) and to determine the relationships between these mechanical responses and biochemical composition. The results showed that both the dynamic compressive and shear stiffness of the cultured constructs increased during culture. The relative energy dissipation in dynamic compression decreased, whereas that in dynamic shear increased during culture. Furthermore, correlation analyses showed that the sulfated glycosaminoglycan (sGAG) content of the cultured construct showed significant correlations with the dynamic modulus in both compression and shear situations. On the other hand, the loss tangent in dynamic compression, which represents the relative energy dissipation capability of the constructs, showed a low correlation with the sGAG content, whereas this capability in shear exhibited moderate correlation. In conclusion, we explored the dynamic viscoelasticity of the tissue-engineered cartilage in dynamic compression and shear, and determined correlations between viscoelasticity and biochemical composition.

scholarly journals Effect of Flaring Gate Piers on Discharge Coefficient for Finite Crest-Length Weirs

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1349
Author(s):  
Zhong Tian ◽  
Wei Wang ◽  
Ruidi Bai ◽  
Nan Li
Keyword(s):  
Comparative Analysis ◽  
Water Surface ◽  
Discharge Coefficient ◽  
Discharge Coefficients ◽  
Water Head ◽  
Contraction Ratio ◽  
Plunging Jets ◽  
Surface Profiles ◽  
Crest Length ◽  
Contraction Angle

The use of flaring gate piers (FGPs) along with finite crest-length weirs changes the shape of plunging jets and increases the efficiency of energy dissipation in some projects; however, the FGPs may affect the discharge capacity. In this study, the flow pattern and discharge coefficient were experimentally investigated under different conditions by varying the weir lengths Lw, contraction ratio β, contraction angle θ, and water heads H. A comparative analysis of the weirs with and without FGPs was performed. For the finite crest-length weirs with FGPs, the water-surface profiles in the flow channel were backwater curves. Moreover, the plunging jets leaving the weir became narrower and then subsequently diffused largely in the transverse and longitudinal directions in air. The discharge coefficients of the weirs with FGPs were approximately equal for various weir lengths. Moreover, following the earlier studies on traditional finite crest-length weirs, a discharge-coefficient equation was developed for the weir with an FGP in this study. The results showed that in the weirs with FGPs, the discharge coefficients clearly increased with the increase in the contraction ratio and water head, but the changes in their values along with the contraction angle were neglected.

RETARDATION EFFECTS IN COVARIANT THREE-DIMENSIONAL BOUND STATE WAVE FUNCTIONS

2005 ◽  
Vol 14 (06) ◽  
pp. 931-947 ◽  
Author(s):  
F. PILOTTO ◽  
M. DILLIG
Keyword(s):  
Bound States ◽  
Three Dimensional ◽  
Bound State ◽  
Relative Energy ◽  
Wave Functions ◽  
Three Dimensions ◽  
State Wave ◽  
Scalar Diquark ◽  
Bound State Wave Function ◽  
Retardation Effects

We investigate the influence of retardation effects on covariant 3-dimensional wave functions for bound hadrons. Within a quark-(scalar) diquark representation of a baryon, the four-dimensional Bethe–Salpeter equation is solved for a 1-rank separable kernel which simulates Coulombic attraction and confinement. We project the manifestly covariant bound state wave function into three dimensions upon integrating out the non-static energy dependence and compare it with solutions of three-dimensional quasi-potential equations obtained from different kinematical projections on the relative energy variable. We find that for long-range interactions, as characteristic in QCD, retardation effects in bound states are of crucial importance.

Lab-on-a-Chip System for Developing and Fluorescence Imaging a Three-Dimensional Model of Pancreatic Islets Under Flow Conditions

2021 ◽  
Vol MA2021-01 (55) ◽  
pp. 1396-1396
Author(s):  
Zbigniew Brzozka ◽  
Patrycja Sokołowska ◽  
Kamil Zukowski ◽  
Justyna Janikiewicz ◽  
Ekzbieta Jastrzebska ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Fluorescence Imaging ◽  
Three Dimensional ◽  
Lab On A Chip ◽  
Dimensional Model ◽  
Flow Conditions ◽  
Three Dimensional Model

Compressor Performance 2D Modelling at Reverse Flow Conditions

2010 ◽  
Author(s):  
L. Gallar ◽  
I. Tzagarakis ◽  
V. Pachidis ◽  
R. Singh
Keyword(s):  
Experimental Data ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Engine Performance ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Compressor Surge ◽  
Compressor Performance ◽  
Shaft Failure

After a shaft failure the compression system of a gas turbine is likely to surge due to the heavy vibrations induced on the engine after the breakage. Unlike at any other conditions of operation, compressor surge during a shaft over-speed event is regarded as desirable as it limits the air flow across the engine and hence the power available to accelerate the free turbine. It is for this reason that the proper prediction of the engine performance during a shaft over-speed event claims for an accurate modelling of the compressor operation at reverse flow conditions. The present study investigates the ability of the existent two dimensional algorithms to simulate the compressor performance in backflow conditions. Results for a three stage axial compressor at reverse flow were produced and compared against stage by stage experimental data published by Gamache. The research shows that due to the strong radial fluxes present over the blades, two dimensional approaches are inadequate to provide satisfactory results. Three dimensional effects and inaccuracies are accounted for by the introduction of a correction parameter that is a measure of the pressure loss across the blades. Such parameter is tailored for rotors and stators and enables the satisfactory agreement between calculations and experiments in a stage by stage basis. The paper concludes with the comparison of the numerical results with the experimental data supplied by Day on a four stage axial compressor.

The superiority of three-dimensional physical models to two-dimensional computer presentations in anatomy learning

2018 ◽  
Vol 52 (11) ◽  
pp. 1138-1146 ◽  
Author(s):  
Bruce Wainman ◽  
Liliana Wolak ◽  
Giancarlo Pukas ◽  
Eric Zheng ◽  
Geoffrey R Norman
Keyword(s):  
Three Dimensional ◽  
Physical Models ◽  
Two Dimensional

scholarly journals Protein Folding: Search for Basic Physical Models

2003 ◽  
Vol 3 ◽  
pp. 623-635 ◽  
Author(s):  
Ivan Y. Torshin ◽  
Robert W. Harrison
Keyword(s):  
Protein Folding ◽  
Tertiary Structure ◽  
Three Dimensional ◽  
Physical Models ◽  
Dimensional Structure ◽  
Computational Techniques ◽  
Linear Sequence ◽  
Physical Forces

How a unique three-dimensional structure is rapidly formed from the linear sequence of a polypeptide is one of the important questions in contemporary science. Apart from biological context ofin vivoprotein folding (which has been studied only for a few proteins), the roles of the fundamental physical forces in thein vitrofolding remain largely unstudied. Despite a degree of success in using descriptions based on statistical and/or thermodynamic approaches, few of the current models explicitly include more basic physical forces (such as electrostatics and Van Der Waals forces). Moreover, the present-day models rarely take into account that the protein folding is, essentially, a rapid process that produces a highly specific architecture. This review considers several physical models that may provide more direct links between sequence and tertiary structure in terms of the physical forces. In particular, elaboration of such simple models is likely to produce extremely effective computational techniques with value for modern genomics.

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