scholarly journals Comparison Between Numerical Flow3d Software and Laboratory Data, For Sediment Incipient Motion.

2022 ◽  
Vol 961 (1) ◽  
pp. 012031
Author(s):  
Rasool Kosaj ◽  
Rafid S Alboresha ◽  
Sadeq O Sulaiman
Keyword(s):  
Laboratory Data ◽  
Small Diameter ◽  
Incipient Motion ◽  
Rigid Boundary ◽  
Laboratory Results ◽  
Computational Fluid Dynamics Cfd ◽  
Bed Slope ◽  
Different Diameters ◽  
3D Software ◽  
Sediment Incipient Motion

Abstract In this paper, the laboratory data were compared with computational fluid dynamics (CFD) Flow3D for predicting the beginning of sediment incipient motion in rigid boundary channel for two types of sands, irrigation, and sewer types, in rectangular flume (0.5*0.5)m cross-section. Tests were made for soil samples with different diameters, specific weights. The testing was performed in slopes ranging from 0.001-0.003 for irrigation types and 0.0025-0.025 for sewer types depending on the original parameter. The Flow-3D software has simulated the laboratory work using scouring models MPM and Nielsen. the relation between sediment incipient motion velocity, particle size, and channel bed slope was predicted. The results were relatively more than laboratory data for the MPM model, while grating convergence for Nielsen model, especially for small diameter sediment. Also, the laboratory results are more close to the results of Flow3D using the Nielsen model when the value of bed slope of the channel is greater, and vice versa when the slope decreases.

scholarly journals CFD Simulation Model of Salt Wedge Propagation

2022 ◽  
Vol 28 (1) ◽  
pp. 76-85
Author(s):  
Aya kh. Shaheed ◽  
Riyadh Z. Azzubaidi
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Cfd Simulation ◽  
Laboratory Data ◽  
Cfd Model ◽  
Salt Wedge ◽  
Laboratory Results ◽  
Computational Fluid Dynamics Cfd ◽  
Bed Slope ◽  
Good Agreement

This study aims to numerically simulate the flow of the salt wedge by using computational fluid dynamics, CFD. The accuracy of the numerical simulation model was assessed against published laboratory data. Twelve CFD model runs were conducted under the same laboratory conditions. The results showed that the propagation of the salt wedge is inversely proportional to the applied freshwater discharge and the bed slope of the flume.  The maximum propagation is obtained at the lowest discharge value and the minimum slope of the flume. The comparison between the published laboratory results and numerical simulation shows a good agreement. The range of the relative error varies between 0 and 16% with an average of 2% and a root mean square error of 0.18. Accordingly, the CFD software is quite valid to simulate the propagation of the salt wedge. 

scholarly journals Effects of relative submergence and bed slope on sediment incipient motion under decelerating flows

2015 ◽  
Vol 63 (4) ◽  
pp. 295-302 ◽  
Author(s):  
Ramin Bolhassani ◽  
Hossein Afzalimehr ◽  
Subhasish Dey
Keyword(s):  
Experimental Study ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
Incipient Motion ◽  
Grain Sizes ◽  
Bed Slope ◽  
Sediment Incipient Motion

Abstract This paper presents the results of an experimental study to quantify the effects of bed slope and relative submergence on incipient motion of sediment under decelerating flows. Experiments were conducted in an experimental tilting-flume of 8 m long 0.4 m wide and 0.6 m deep with glass-walls. Three uniform sediments with median grain sizes of 0.95, 1.8 and 3.8 mm and three bed slopes of 0.0075, 0.0125 and 0.015 were used under decelerating flow. The main conclusion is that the Shields diagram, which is commonly used to evaluate the critical shear stress, is not suitable to predict the critical shear stress under decelerating flows.

Experimental analysis of sediment incipient motion in rigid boundary open channels

2017 ◽  
Vol 17 (6) ◽  
pp. 1281-1298 ◽  
Author(s):  
Mir Jafar Sadegh Safari ◽  
Hafzullah Aksoy ◽  
Necati Erdem Unal ◽  
Mirali Mohammadi
Keyword(s):  
Experimental Analysis ◽  
Open Channels ◽  
Incipient Motion ◽  
Rigid Boundary ◽  
Sediment Incipient Motion

Structural Organization and Distribution of Fiber Types in Extraocular Muscles of Cats

1972 ◽  
Vol 30 ◽  
pp. 34-35
Author(s):  
Asish C. Nag ◽  
Lee D. Peachey
Keyword(s):  
Fiber Type ◽  
Light And Electron Microscopy ◽  
Small Diameter ◽  
Extraocular Muscles ◽  
Fiber Types ◽  
Distinctive Features ◽  
Superior Rectus ◽  
Adult Cats ◽  
Different Diameters ◽  
Orbital Region

Cat extraocular muscles consist of two regions: orbital, and global. The orbital region contains predominantly small diameter fibers, while the global region contains a variety of fibers of different diameters. The differences in ultrastructural features among these muscle fibers indicate that the extraocular muscles of cats contain at least five structurally distinguishable types of fibers.Superior rectus muscles were studied by light and electron microscopy, mapping the distribution of each fiber type with its distinctive features. A mixture of 4% paraformaldehyde and 4% glutaraldehyde was perfused through the carotid arteries of anesthetized adult cats and applied locally to exposed superior rectus muscles during the perfusion.

scholarly journals CT pulmonary angiography in COVID-19 pneumonia: relationship between pulmonary embolism and disease severity

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Aya Yassin ◽  
Maryam Ali Abdelkader ◽  
Rehab M. Mohammed ◽  
Ahmed M. Osman
Keyword(s):  
Pulmonary Embolism ◽  
Disease Severity ◽  
Laboratory Data ◽  
Pulmonary Angiography ◽  
Significant Relation ◽  
Ct Pulmonary Angiography ◽  
Laboratory Results ◽  
Severity Of The Disease ◽  
The Relationship ◽  
D Dimer

Abstract Background Pulmonary embolism (PE) is one of the known sequels of COVID-19 infection. We aimed to assess the incidence of PE in patients with COVID-19 infection and to evaluate the relationship between the CT severity of the disease and the laboratory indicators. This was a retrospective study conducted on 96 patients with COVID-19 infection proved by positive PCR who underwent CT pulmonary angiography (CTPA) with a calculation of the CT severity of COVID-19 infection. Available patients’ complaint and laboratory data at the time of CTPA were correlated with PE presence and disease severity. Results Forty patients (41.7%) showed positive PE with the median time for the incidence of PE which was 12 days after onset of the disease. No significant correlation was found between the incidence of PE and the patients’ age, sex, laboratory results, and the CT severity of COVID-19. A statistically significant relation was found between the incidence of PE and the patients’ desaturation, hemoptysis, and chest pain. A highly significant correlation was found between the incidence of PE and the rising in the D-dimer level as well as the progressive CT findings when compared to the previous one. Conclusion CT progression and the rising in D-dimer level are considered the most important parameters suggesting underlying PE in patients with positive COVID-19 infection which is commonly seen during the second week of infection and alert the use of CT pulmonary angiography to exclude or confirm PE. This is may help in improving the management of COVID-19 infection.

scholarly journals Design of a new hybrid artificial neural network method based on decision trees for calculating the Froude number in rigid rectangular channels

2016 ◽  
Vol 64 (3) ◽  
pp. 252-260 ◽  
Author(s):  
Isa Ebtehaj ◽  
Hossein Bonakdari ◽  
Amir Hossein Zaji ◽  
Charles Hin Joo Bong ◽  
Aminuddin Ab Ghani
Keyword(s):  
Decision Trees ◽  
Incipient Motion ◽  
Rigid Boundary ◽  
Sediment Bed ◽  
Economical Design ◽  
Rectangular Channels ◽  
Wide Range ◽  
Practical Engineering ◽  
Artificial Neural Network Method ◽  
Bed Thickness

Abstract A vital topic regarding the optimum and economical design of rigid boundary open channels such as sewers and drainage systems is determining the movement of sediment particles. In this study, the incipient motion of sediment is estimated using three datasets from literature, including a wide range of hydraulic parameters. Because existing equations do not consider the effect of sediment bed thickness on incipient motion estimation, this parameter is applied in this study along with the multilayer perceptron (MLP), a hybrid method based on decision trees (DT) (MLP-DT), to estimate incipient motion. According to a comparison with the observed experimental outcome, the proposed method performs well (MARE = 0.048, RMSE = 0.134, SI = 0.06, BIAS = -0.036). The performance of MLP and MLP-DT is compared with that of existing regression-based equations, and significantly higher performance over existing models is observed. Finally, an explicit expression for practical engineering is also provided.

scholarly journals On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

2014 ◽  
Vol 62 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Mir-Jafar-Sadegh Safari ◽  
Mirali Mohammadi ◽  
Golezar Gilanizadehdizaj
Keyword(s):  
Cross Sections ◽  
Research Work ◽  
Fixed Bed ◽  
Deposition Condition ◽  
Incipient Motion ◽  
Rigid Boundary ◽  
Cross Sectional ◽  
Motion Equations ◽  
Sectional Shape ◽  
Minimum Velocity

Abstract The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992) and Mohammadi (2005) are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

scholarly journals Numerical Investigations on the Instability of Boulders Impacted by Experimental Coastal Flows

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1557
Author(s):  
Liang Wang ◽  
Lidia Bressan ◽  
Stefano Tinti
Keyword(s):  
Laboratory Data ◽  
High Energy ◽  
Coastal Sediments ◽  
Water Model ◽  
Incipient Motion ◽  
Shallow Water Model ◽  
Instability Condition ◽  
Wide Range ◽  
Drag And Lift ◽  
The University

Coastal boulders transported inland by marine hazards, such as tsunamis and storms, are commonly found worldwide. Studies on the transport process of coastal boulders contribute to the understanding of a wide range of phenomena such as high-energy flow events, fluid-structure interaction, and coastal sediments. Consequently, it is crucial to understand how boulders move, but even more important to determine the instability condition for boulder transport. The hydrodynamic formulas including drag and lift coefficients are widely used to predict the incipient motion of boulders while few studies are conducted to evaluate the capability of these formulas. Recently, a series of laboratory experiments carried out at the Hydraulic Engineering Laboratory (Italian acronym LIDR) of the University of Bologna, Italy, revealed that boulders can start moving when the flow height and flow velocity are lower than the theoretical threshold computed by hydraulic formulas. In this paper, we use a numerical shallow water model to reproduce these freely available laboratory data with the aim of testing the capability of the model in capturing the main evolution of the process, and of casting new light on the instability condition of coastal boulders.

Quantity quotient reporting versus z-value for standardizing quantitative laboratory results

2017 ◽  
Vol 41 (2) ◽  
Author(s):  
Rainer Haeckel ◽  
Werner Wosniok ◽  
Eberhard Gurr ◽  
Theo Postma ◽  
Thomas Streichert
Keyword(s):  
Intelligence Quotient ◽  
Laboratory Data ◽  
Medical Data ◽  
Laboratory Results ◽  
Enormous Amount ◽  
Electronic Storage ◽  
Z Value ◽  
Z Transformation

Abstract:The rapid increase to digitalize whatever is possible in human lives will lead to electronic storage of medical data probably during the whole life of most individuals. This requires standardization and condensation of an enormous amount of data. Most laboratory data are already reported in digitalized form, but they are far from being sufficiently standardized. Several attempts for standardization have been suggested. The most common standardizing approach is the z-transformation of laboratory data. It is proposed to modify the z-value to a quantity quotient in analogy to the intelligence quotient well known even to laymen.

The Stolz and ASME-AGA Orifice Equations Compared to Laboratory Data

1979 ◽  
Vol 101 (4) ◽  
pp. 483-490 ◽  
Author(s):  
R. W. Miller
Keyword(s):  
Systematic Error ◽  
Laboratory Data ◽  
High Accuracy ◽  
Laboratory Results ◽  
Using Data ◽  
The U.S ◽  
Ratio Range ◽  
Better Than

Today, technical experts in Europe and the U.S. are debating the merits of conducting new orifice flowmeter tests, establishing the effects of upstream disturbance and conducting other programs to improve orifice flowmetering accuracy. ISO has adopted a new “Universal” orifice equation proposed by J. Stolz. With over 1,000,000 orifice flowmeters in use today, any change in the coefficient value is of major concern. There are now two equations for calculating flange tap coefficients, the ASME-AGA equation and the ISO equation. They differ in form, predict different coefficients, and have different overall uncertainties (tolerance value). This paper presents a comparison between actual laboratory data and these two equations. The data were obtained in two high accuracy laboratories on flange tap orifice flowmeters fabricated by different manufacturers to AGA or ASME recommendations. Data plate dimensions were used in all calculations, and conformity to ASME or AGA requirements was the responsibility of the manufacturer. For this reason it is believed that the analysis more nearly represents what the user can expect if the in-site installation approached that of the laboratory. Results indicate that over the same beta ratio range the ISO (or Stolz) equation form is significantly better than the present ASME-AGA form. The overall uncertainty (or tolerance), although smaller than the ASME-AGA, is still ± 1 percent because of a 0.4 percent systematic error. Results of work by Miller-Kneisel, using data from three different laboratories, are presented to indicate that ±0.5 percent remains achievable; for betas up to 0.7 using the ISO (Stolz) equation form with modified coefficients.

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