scholarly journals Effect of Block Geometry and Divergence of Baffled Chute on Downstream Scour Pattern

2019 ◽  
Author(s):  
Morteza karimi Chahartaghi ◽  
sohrab Nazari ◽  
Mohsen Solimani Babarsad
Keyword(s):  
Physical Model ◽  
Maximum Depth ◽  
Scour Hole ◽  
The Mean ◽  
Baffle Block

The effect of divergence of chute sidewalls with three different baffle block geometries namely USBR, trihedral and semicircular blocks, as well as the depth and dimensions of the scour hole downstream of the chute were studied using a physical model. For this purpose, 9 models of baffled chutes were designed and constructed with divergence ratios of 1.45, 1.75, and 2.45 and without divergence (with a divergence ratio of 1). Comparing the results on the effect of block geometry at different divergence ratios revealed that the use of blocks proposed in this study instead of standard USBR blocks reduced the mean and maximum scour hole by 50%. For a given block geometry, the mean depth, maximum depth, and length of scour hole were reduced by 75%, 58%, and 50%, respectively.

scholarly journals Investigating the Effects of the Block Geometries and Sidewall Divergences on the Local Scour Downstream of Baffled Chute Spillways

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Morteza Karimi Chahartaghi ◽  
Sohrab Nazari ◽  
Mohsen Solimani Babarsad
Keyword(s):  
Flow Characteristic ◽  
Construction Cost ◽  
Maximum Depth ◽  
Bureau Of Reclamation ◽  
Trapezoidal Shape ◽  
Scour Hole ◽  
Scour Hole Dimensions ◽  
Hole Dimensions ◽  
Baffle Block ◽  
The U.S

Due to the lack of any specific study about the sidewalls and other blocks’ changes in the case of hydraulic and scour downstream, the present study was conducted to investigate this issue. For this purpose, drainage projects and spillway chutes, as well as many baffle block chutes, were designed and constructed with the parallel sidewalls and trapezoidal shape using the U.S. Bureau of Reclamation (USBR) instructions. Three divergence ratios of b 1 / b 2 = 1.45 , 1.75 ,   and   2.45 , a parallel sidewall of b 1 / b 2 = 1 , and also three geometry blocks including trapezoidal USBR, trihedral, and semicircle blocks were applied and tested in the hydraulic laboratory using a baffle chute with the slope of (2 : 1), (H : V). The material used in this study was sediment sand with a uniform grain size of d50 = 1.2 mm, 15 cm of thickness, and 2 m of length. The experiment was conducted with seven different discharges in lasting condition, and the flow characteristic and scour hole dimensions were measured. The results revealed that in comparison with the USBR blocks, changes in the baffle sidewall and block shape made an approximate 50% reduction in the maximum depth of the scour hole. Thus, increasing the divergence ratio from 1 to 2.45 had a significant effect on reducing the maximum depth and the topographic shape of the scour hole. According to the range mentioned in the literature for the Weber number, the scale effect was negligible for the chute with baffle blocks. Generally, it can be concluded that the sidewall changes also can make a reduction in the number of overbaffle blocks, causing a reduction in the construction cost.

scholarly journals Physical model study of bedrock scour downstream of dams due to spillway plunging jets

2020 ◽  
Vol 62 (3) ◽  
Author(s):  
A Bosman ◽  
G R Basson
Keyword(s):  
Physical Model ◽  
Linear Regression Analysis ◽  
Scour Depth ◽  
Model Study ◽  
Fissured Rock ◽  
Scour Hole ◽  
Plunging Jets ◽  
Concrete Blocks ◽  
Rock Bed ◽  
Equilibrium Scour Depth

The erosive power of a free-falling high-velocity water jet, flowing from a dam spillway, could create a scour hole downstream of the dam, endangering the foundation of the dam. Despite extensive research since the 1950s, there is presently no universally agreed method to predict accurately the equilibrium scour depth caused by plunging jets at dams. These formulae yield a large range of equilibrium scour dimensions. The hydrodynamics of plunging jets and the subsequent scour of a rectangular, horizontal and vertical fissured rock bed were investigated in this study by means of a physical model. Equilibrium scour hole geometries for different fissured dimensions (simulated with rectangular concrete blocks tightly prepacked in a regular rectangular matrix), for a range of flow rates, plunge pool depths, and dam height scenarios were experimentally established with 31 model tests. From the results, non-dimensional formulae for the scour hole geometry were developed using multi-linear regression analysis. The scour depth results from this study were compared to various analytical methods found in literature. The equilibrium scour hole depth established in this study best agrees with that predicted by the Critical Pressure method.

Further studies into proximal interphalangeal joint dimensions for the design of a surface replacement prosthesis: Medullary cavities and transverse plane shapes

1997 ◽  
Vol 211 (5) ◽  
pp. 377-390 ◽  
Author(s):  
H E Ash ◽  
A Unsworth
Keyword(s):  
Sagittal Plane ◽  
Proximal Phalanx ◽  
Frontal Plane ◽  
Medullary Canal ◽  
Transverse Plane ◽  
Maximum Depth ◽  
Surface Replacement ◽  
The Mean ◽  
Middle Ring ◽  
Replacement Prosthesis

The proximal and middle phalanges from 83 proximal interphalangeal joints (PIPJs) were set in clear plastic and sectioned in the transverse plane leaving the heads whole. The sections were cleaned, shadowgraphed and measured. The medullary canals were marked on sagittal and frontal plane shadowgraphs of the intact bones and analysed. The information was then used in the design of a surface replacement prosthesis for the PIPJs. The main dorsal surface of the proximal phalanx (PP) was found to be angled to the longitudinal baseline of the bone by a mean of 5.19°. This angle increased just proximal to the phalangeal head to a mean of 11.84°. The mean ratio between these angles was 2.71. The phalangeal shaft bone was thicker laterally than dorsally and palmarly, and thicker dorsally than palmarly for the proximal and middle phalanges throughout the length of the bone. The shape and size of the transverse cross-section of the medullary canal changed throughout the length of the shaft. The centreline of the PP medullary canal coincided with the midline of the bone in the frontal plane and was approximately a straight line along the length of the canal. In the sagittal plane the centreline was slightly palmar to the midline and the angle between it and the longitudinal baseline of the bone changed along the length of the canal. In the region of the shaft just proximal to the PP head (where the stem of a surface replacement prosthesis would fit) the mean angle was 10.63°. The centreline was offset dorsally from the centre of rotation of the PIPJ by a mean of 0.83 mm, 0.83 mm, 0.80 mm and 0.57 mm for the index, middle, ring and little fingers respectively, with an overall mean of 0.76 mm. The mean PP head heights (transverse plane) were 9.17 mm, 9.33 mm, 8.73 mm and 7.40 mm and the mean PP widths (transverse plane) were 12.86 mm, 13.25 mm, 12.75 mm and 10.54 mm for the index, middle, ring and little fingers respectively. The mean angle between the lateral sides of the condyles to the transverse baseline was 78.35° and the mean distance from the centreline of the PP head (transverse plane) to the bases of the two condyles was 4.69 mm. The mean maximum depth of the PP head intercondylar sulcus in the frontal plane was 0.72 mm and in the transverse plane, the mean maximum depth of the intercondylar sulcus on the anterior face was 0.82 mm.

Local scour of cohesive beds downstream of a rigid apron

2017 ◽  
Vol 44 (11) ◽  
pp. 935-944 ◽  
Author(s):  
Hossein Hamidifar ◽  
Mohammad Hossein Omid
Keyword(s):  
Grain Size ◽  
Empirical Equation ◽  
Scour Depth ◽  
Removal Mechanism ◽  
Sediment Grain Size ◽  
Scour Hole ◽  
Hole Profile ◽  
The Mean ◽  
New Equation ◽  
Individual Particles

In this paper, the physics of scour hole in a mixed sand–clay bed downstream of an apron is studied experimentally. Seven combinations of sand–clay mixtures including clay contents, Cc, ranging from 0 to 0.4 were used. The results show that Cc = 0.4 can reduce the maximum scour depth, εm, up to about 80% for all the densimetric Froude numbers in the range of the present study. An empirical equation has been proposed for calculation of εm in sand–clay mixtures with the mean error of 0.12. The removal mechanism of sediments from the bed was different based on the Cc. For low clay contents, i.e., Cc ≤ 15%, individual particles were detached from the bed. At higher Cc, clusters of particles were separated and moved downstream with the flow. A new equation has been proposed to predict the dimensionless scour hole profile in mixed sand–clay sediments. Dimensionless graphs have been presented for incorporating the effect of tailwater depth and sediment grain size on the main characteristics lengths in sand–clay mixtures.

Variation in dive behavior of Cuvier’s beaked whales with seafloor depth, time-of-day, and lunar illumination

2020 ◽  
Vol 644 ◽  
pp. 199-214 ◽  
Author(s):  
J Barlow ◽  
GS Schorr ◽  
EA Falcone ◽  
D Moretti
Keyword(s):  
Surface Waters ◽  
Predator Avoidance ◽  
Time Of Day ◽  
Maximum Depth ◽  
Near Surface ◽  
Beaked Whales ◽  
Energetic Constraints ◽  
The Mean ◽  
Ziphius Cavirostris ◽  
Foraging Time

Depth distributions were analyzed from a study of 19 Cuvier’s beaked whales Ziphius cavirostris that were tagged with satellite transmitting instruments off southern California, USA. Over 113000 depth measurements were made over the equivalent of ~200 sampling days. The mean foraging depth was 1182 m (SD = 305 m), and the mean of the maximum depth of all foraging dives was 1427 m (SD = 298 m). Mean foraging depths increased with seafloor depths up to a maximum of ~1300 m at a seafloor depth of 1900 m, but decreased slightly to a mean of ~1200 m at seafloor depths of 2000-4000 m. Near-bottom habitat appears to be important for foraging; whales spent ~30% of their foraging time within 200 m of the bottom at seafloor depths of 1000-2000 m. However, little foraging time was spent near the bottom at seafloor depths greater than 2000 m. The percentage of time spent at near-surface depths (<50 m) was more than twice as high at night (25%) than during the day (12%). Lunar light also appears to affect diving, with 28% of dark nights and only 17% of brightly moonlit nights spent at these near-surface depths. The apparent avoidance of surface waters during daytime and on brightly moonlit nights is consistent with avoidance of visual predators. A considerably greater fraction of time was spent foraging at night (24.8%) than during the day (15.7%), possibly due to energetic constraints imposed by predator avoidance during the day.

A physical model of the turbulent boundary layer consonant with mean momentum balance structure

2007 ◽  
Vol 365 (1852) ◽  
pp. 823-840 ◽  
Author(s):  
Joe Klewicki ◽  
Paul Fife ◽  
Tie Wei ◽  
Pat McMurtry
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Physical Model ◽  
Momentum Equation ◽  
Momentum Balance ◽  
Dynamical Structure ◽  
Mean Flow ◽  
Structure And Dynamics ◽  
The Mean ◽  
Balance Structure

Recent studies by the present authors have empirically and analytically explored the properties and scaling behaviours of the Reynolds averaged momentum equation as applied to wall-bounded flows. The results from these efforts have yielded new perspectives regarding mean flow structure and dynamics, and thus provide a context for describing flow physics. A physical model of the turbulent boundary layer is constructed such that it is consonant with the dynamical structure of the mean momentum balance, while embracing independent experimental results relating, for example, to the statistical properties of the vorticity field and the coherent motions known to exist. For comparison, the prevalent, well-established, physical model of the boundary layer is briefly reviewed. The differences and similarities between the present and the established models are clarified and their implications discussed.

Saturation of Deformation Twinning in Magnesium Alloys

2016 ◽  
Vol 879 ◽  
pp. 2084-2087 ◽  
Author(s):  
Wen Wen Wei ◽  
Erwin Povoden-Karadeniz ◽  
Ernst Kozeschnik
Keyword(s):  
Physical Model ◽  
Magnesium Alloys ◽  
Deformation Twinning ◽  
Mg Alloy ◽  
Alloy Az31 ◽  
The Mean ◽  
Twin Growth

The saturation of primary tensile twins in heavily textured Mg-alloy AZ31 is investigated, and their strain accommodation limit is evaluated. EBSD results suggest that the mean number of twins per grain saturate rapidly, followed by the stop of twin growth. Twinning saturation is included in a physical model of twin evolution.

scholarly journals Biometric study of the width, length and depth of the root trunk groove of human lower second molars

2002 ◽  
Vol 16 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Constanza Marin de los RIOS ◽  
Francisco Emílio PUSTIGLIONI ◽  
Giuseppe Alexandre ROMITO
Keyword(s):  
Statistical Analysis ◽  
Maximum Depth ◽  
Second Molar ◽  
Trunk Region ◽  
Lingual Surface ◽  
Apical Direction ◽  
Mean Width ◽  
The Mean ◽  
The Right ◽  
Root Surfaces

One hundred human lower second molars, 51 from the left side and 49 from the right side, extracted due to their poor clinical and radiographic conditions were utilized in this study. Using a Contracer apparatus, the profiles of the buccal and lingual root surfaces of these teeth were traced on a millimeter-scaled paper. The profiles were registered from the cementoenamel junction (CEJ), millimeter by millimeter, up to the entrance of the furcation. The width, length and depth of the root trunk groove, as well as the length of the root trunk, were studied. After statistical analysis (p < 0.05) it was possible to conclude that: a) the mean width of the root trunk groove on the buccal surface was 3.6 mm and, on the lingual surface, 3.3 mm; b) the mean depth of the root trunk groove on the buccal surface was 0.88 mm and, on the lingual surface, 0.77 mm; c) the mean length of the root trunk groove on the buccal surface was 2.93 mm and, on the lingual surface, 3.61 mm. The mean length of the root trunk on the buccal surface was 3.09 mm and, on the lingual surface, 3.91 mm (p < 0.025). There was a coincidence between the length of the root trunk and that of its groove in 90.2% of the buccal surfaces of the samples from the left side, and in 77.5% of the samples from the right side; on the lingual surface, the coincidence occurred in 77.5% of the teeth from the left side, and on 88.3% of the teeth from the right side. This work revealed that there is a concavity on the root trunk region of the lower second molar, whose depth and width were greater on the buccal surface and whose length was greater on the lingual surface. The depth of the root trunk groove increased in the apical direction, with maximum depth in the last millimeter of the root trunk. The root trunk was longer on the lingual surface than it was on the buccal surface.

scholarly journals Analysis of the Magnetic Anomalies of Buried Archaeological Ovens of Aïn Kerouach (Morocco)

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Abderrahim Ayad ◽  
Saâd Bakkali
Keyword(s):  
Magnetic Anomalies ◽  
Maximum Depth ◽  
Downward Continuation ◽  
Magnetic Data ◽  
Archaeological Sites ◽  
Depth Variation ◽  
15Th Century ◽  
The Mean

Aïn Kerouach is one of the most important archaeological sites in the northern part of Morocco. The main buried archaeological ruins in this area were surveyed in 1977 using magnetic prospecting. This survey highlights the mean anomalies that are related to potteries ovens built to the Marinid dynasty that governed Morocco from the 13th to the 15th century. In order to find the maximum depth of the sources, we computed the enhanced downward continuation filter in order to highlight the magnetization contrasts in high detail, depending on the depth downward included in the computation. The main goal is providing a reliable mapping to observe the ovens in depth by shifting the data below the plane of measurement. The results showed an important depth variation of the main ovens given by the original magnetic map and revealed others. Indeed, the downward continuation process applied to analyze the magnetic data shows its efficiency to highlight the buried archaeological structures.

scholarly journals A new formula based on computational fluid dynamics for estimating maximum depth of scour by jets from overflow dams

2014 ◽  
Vol 16 (5) ◽  
pp. 1210-1226 ◽  
Author(s):  
Sherong Zhang ◽  
Bohui Pang ◽  
Gaohui Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Maximum Velocity ◽  
Maximum Depth ◽  
Scour Depth ◽  
Absolute Deviation ◽  
Scour Hole ◽  
Computational Fluid Dynamics Cfd ◽  
New Formula ◽  
Lm Algorithm

The prediction of the maximum depth of the scour hole formed downstream of overflow dams is critical in determining the safety of hydraulic structures. Most of the conventional formulae are not able to consider complex hydraulic and morphologic conditions. A new formula for estimating the maximum depth of the scour hole based on computational fluid dynamics (CFD), which can be used to simulate the complicated phenomenon, is proposed. The relationship between the maximum velocity in numerical simulations and the maximum scour depth is reflected in this formula, which is established using the Levenberg–Marquardt (LM) algorithm. The validity of this proposed formula is discussed by comparing this formula with three other conventional formulae. The prediction formula based on CFD is applied to the Wuqiangxi Dam, and the absolute deviation of the predicted maximum scour depth (35.44 m) from the measured depth (36.00 m) is 0.56 m.

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