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Experimental results on the nature-like fishway induced flow field and its relation to fish behaviour are presented. A rocky-ramp with 5% slope was built along a 8.9 m × 0.9 m × 0.6 m laboratory fl...

Russell's vipers (Daboia russelii and D. siamensis) inhabit 10 South and South East Asian countries. People envenomed by these snakes suffer coagulopathy, bleeding, shock, neurotoxicity, acute kidney injury and local tissue damage leading to severe morbidity and mortality. An unusual complication of Russell's viper bite envenoming in Burma (D. siamensis) and southern India (D. russelii) is hypopituitarism but until now it has not been reported elsewhere. Here, we describe the first case of hypopituitarism following Russell's viper bite in Sri Lanka, review the literature on this subject and make recommendations for endocrine investigation and management. A 49-year-old man was bitten and seriously envenomed by D. russelii in 2005. He was treated with antivenom but although he recovered from the acute effects he remained feeling unwell. Hypopituitarism, with deficiencies of gonadal, steroid and thyroid axes, was diagnosed 3 years later. He showed marked improvement after replacement of anterior pituitary hormones. We attribute his hypopituitarism to D. russelii envenoming. Russell's viper bite is known to cause acute and chronic hypopituitarism and diabetes insipidus, perhaps through deposition of fibrin microthrombi and haemorrhage in the pituitary gland resulting from the action of venom procoagulant enzymes and haemorrhagins. Forty nine cases of hypopituitarism following Russell's viper bite have been described in the English language literature. Patients with acute hypopituitarism may present with hypoglycaemia and hypotension during the acute phase of envenoming. Those with chronic hypopituitarism seem to have recovered from envenoming but present later with features of hypopituitarism. Over 85% of these patients had suffered acute kidney injury immediately after the bite. Steroid replacement in acute hypopituitarism is life saving. All 11 patients with chronic hypopituitarism in whom the outcome of treatment was reported, showed marked improvement with hormone replacement. Unrecognized acute hypopituitarism is potentially fatal while chronic hypopituitarism can be debilitating. Physicians should therefore be aware of this complication of severe envenoming by Russell's vipers, especially in Burma and South India, so that the diagnosis may be made without delay and replacement started with essential hormones such as hydrocortisone and thyroxine.

Mean and turbulent flow characteristics on the upstream and downstream sides of the screen in a flow diversion channel have important implications for operation and maintenance (e.g., sedimentation) and for assessing fish behavior related to flow turbulence. This technical note extends an earlier study on mean flow near screens to turbulence characteristics. Acoustic Doppler velocimeter was used to explore three-dimensional mean and turbulent flow characteristics on the upstream and downstream sides of vertical angled fish screens. The present study confirms the two-dimensional mean velocity observations of the previous experimental work and shows that the vertical mean velocities are less than 10% of the local magnitudes of longitudinal velocity and hence can be ignored. Horizontal components of the mean velocity on the downstream side of the screen were relatively small, but the turbulent velocity fluctuations were two to three times as intense as those measured on the upstream side.

Flow patterns in the shallow turbulent near-wakes behind bed-mounted cylinders are investigated on smooth and rough beds. A wall wake analysis revealed that the flows in the region away from the bed are similar and well described by the plane wake equation. Wall wake similarity was also observed for turbulent kinetic energy and primary Reynolds stress for moderate to deeply submerged cylinders.Wake analyses in the horizontal plane revealed that similarity of mean velocity profiles across the flow exist in the near-wake region at all elevations for slightly submerged and surface piercing cylinders; and at all elevations below the object height close to moderate and deeply submerged cylinders. For slightly submerged and surface piercing cylinders similarity was observed in the near-wake region between the non-dimensional velocity profiles across the wake and the plane wake equation. However, the similarity of the velocity profiles improves if a modified transverse length scale is used for shallow near-wake ...

This paper presents the results of an experimental study of flow around cylindrical objects on a rough bed in an open channel. This is an extension of a previous study of flow around cylinders on a smooth bed. The purpose of this study is to explore the effects of bed roughness on the characteristics of the deflected flow around cylindrical objects and the resulting bed-shear stress distributions. Similar to the previous study cylindrical objects of equal diameter and four heights were tested under similar flow conditions producing four different levels of submergence. Bed shear stress and deflected flow velocities were measured by a thin yaw-type Preston probe after a set of flow visualization tests. Flow visualization tests showed that the horse-shoe vortex systems on the rough bed occupy a relatively greater width compared to the smooth bed. Unlike smooth bed observations, the flow separation point upstream of the cylinder was not dependent on the level of submergence as the separation points were foun...

This paper presents the results of an experimental study of flow around cylindrical objects in an open channel. Cylindrical objects of equal diameter and four heights were tested under similar flow conditions producing four different levels of submergence, including a surface piercing bridge-pier-like cylinder. Different flow elements and their locations were identified using a set of flow visualization tests. Observations made from the flow visualization tests were then verified by measurements of bed-shear stress and deflected flow velocity around the cylinders. Horse-shoe vortex systems were found to appear closer to the submerged cylinders compared to a surface piercing cylinder. The increase in dimensionless bed-shear stress is found to be inversely related to the level of submergence of the cylinders. Bed-shear stress results presented in this paper will be valuable for a qualitative understanding of the scour potential of flow around submerged cylinders. Mean velocity profiles in the deflected flow...

This paper presents the results of an experimental study of louvers that are used for diversion of fish from water intakes and canals. This investigation was conducted in two phases. Phase I involved the field testing of a louver with curved slats for the guidance of hatchery-reared juvenile rainbow trout (Onchorhyncus mykiss) for louver angles θ of 7.2° and 17.0°. Phase II was a laboratory study with flat slats placed perpendicular to the approaching flow with θ of 10.0° and 15.0°. The velocity in the bypass in terms of the approach velocity increased to 1.7 and 2.5, respectively, for the curved and flat louvers for a bypass width b equal to 5% of the width of the approach channel B. The discharge in the bypass channel Qb in terms of the discharge in the approach channel Q was 0.15 and 0.20 for b/B = 0.10 for the curved and flat louvers, respectively, and Qb/Q = 0.07 for b/B = 0.05 for both the curved and flat louver slats. Key words: fish diversion, louvers, canals, open channels, water intakes, turbulent flows.

This paper presents a simple method to predict flow diversion by vertical angled screens in open channels. The performance of this method has been compared with the experimental results from a recent laboratory study of vertical angled screens. This method is then used to predict the effect of screen porosity, variation of porosity along the length of the screen, and several other factors on the flow division. The results of this investigation would be useful in the design of vertical angled screens for fish protection at water intakes from rivers for irrigation, and other industrial uses.Key words: fish screens, intakes, water flow, irrigation canals, open channel flow, hydraulics and fish diversion.

Assuming that skimming flow occurs when the jet leaving a step has a slope equal to that of the stepped spillway when it impinges on the pool behind it on the next step, an equation has been developed to predict the incipient value of \Iy\dc/\ih, where \iy\dc = critical depth and \ih = step height. This equation was found to agree well with most of the experimental observations for \ih/\il greater than about 1.0, where \il = step length. For \ih/\il = 1.7, the incipient value of \iy\dc/\ih = 0.24, whereas for values of \ih/\il smaller than about 0.8, \iy\dc/\ih is almost constant at 0.8.

This technical note discusses two questions related to three-tube (pitch or yaw) pitot probes, which are used for measuring the velocity vectors in 2D flows. When a pitch probe is used in flows in which the third component of the velocity is small but not zero, it is important to know the error this causes in the measurement of the velocity vector. Calibration experiments on a pitch probe showed that as long as the yaw angle is less than 14°, the relative error in the velocity measured by the pitch probe is less than 3% and the error in the pitch angle is less than 1°. Typically a pitch or yaw probe can only be used when the angle of attack is less than approximately 50°. The second part of this work addresses the practical issues associated with pretilting the probe to measure flows at angles greater than 50°.

This paper presents the concept and development of a four-tube probe for the measurement of the three velocity components in 3D flows. The necessary calibration curves have been developed and are presented along with a procedure to use this probe. This probe is more convenient to use than the traditional five-tube probe and is believed to be useful for the measurement of the three components of velocity in 3D flows in the laboratory. It has already been used successfully in the measurement of the velocity field in a vertical slot fishway.

This paper presents the results of a laboratory photographic study on the characteristics of vertical circular jets discharged from the bed at right angles into crossflows of finite depth. Such jets have been divided into two groups termed as deep water and shallow water jets. A parameter has been developed to distinguish between deep and shallow water jets. While deep water jets are generally similar to jets in crossflows of large extent, shallow water jets exhibit a number of differences including bifurcation. Correlations have been developed for the characteristics of both deep and shallow water jets. The results of this study are important and useful for the hydraulic design of submerged outfalls in rivers.

This paper presents the results of a laboratory study on the erosion of noncohesive sediment beds made of three different mixtures by deeply submerged plane turbulent wall jets. The sediment mixtures had median sizes of 6.75, 1.32, and 1.62 mm, and geometric standard deviations of 1.32, 2.02, and 3.13. The main objectives were to study the effect of sediment gradation on the asymptotic scour size and determine an effective size for the sediment mixtures for predicting erosion. The experimental observations and analysis presented in this study established that the sediment nonuniformity has a significant effect on the size of the scour hole produced by the jet. The effective size of the sediment mixture for obtaining a good correlation for the depth of scour was found to be d95 rather than d50 for defining the densimetric particle Froude number, Fo. The average reduction due to armoring in the maximum scour depth and dune height was found to be ∼60%, and it was found to be 50% for the scour hole length and...

This technical note presents the results of an experimental study on the distribution of water in very high velocity water jets in air. Three jets with diameters of 2, 2.5, and 3 mm with velocities...

Exploratory physical-model studies were made of the hydraulics of stormwater dropshafts in the city of Edmonton. Under certain conditions, it is necessary to provide a curved inlet at the top of the dropshaft to increase its carrying capacity. Except for very small discharges, the falling water in the dropshaft does not form a coherent central jet but takes the form of a complex jet with a spreading flow around the periphery of the dropshaft. Such a flow also forms a pool at the bottom of the shaft. The energy loss in the dropshaft is significant. For the case studied, with the diameter of the shaft (Ds) equal to about twice the diameter (D) of the inflow sewer and a fall of 6.6Ds, and over a wide range of flow rates, the relative energy loss in the dropshaft was about 80–95%. Further, the air flow Qa required by the falling water, relative to the water flow rate Q, decreased from about 1.4 to 0.5 as Q* increased from 0.1 to about 1.0. Q*=Q/(gD5).Q= water discharge and g= acceleration due to gravity.

This paper presents the results of a laboratory study on the dilution produced in the mixing region by a circular turbulent wall (bed) jet of diameter d , discharged at right angles into a cross flow of depth D , with jet velocities varied from 2 to 12 times the mean velocity of the cross flow. For a depth-to-diameter ratio D /d of 20, minimum dilutions of about 100 were obtained in the mixing region, which extended through the momentum dominated near and far fields, to the passive plume region. A correlation has been developed to predict the minimum dilution in the mixing region in terms of a transformed distance αx/d. Concentration profiles in the vertical plane along the axis of the deflected jet as well as in the transverse plane of maximum concentration were found to be similar. Some observations have also been made for D /d equal to 10 and 5. The results of this study can be used for designing efficient outfalls in shallow rivers.

This paper presents a brief analysis of uniform open channel flow in circular pipes and introduces a dimensionless discharge parameter Q*. When the pipe just flows full, Q* becomes Q*f which varies inversely with a modified Manning's n written as n*. This relationship has been checked with experimental observations.

This paper considers energy dissipation by jet diffusion in drop shafts used in urban stormwater systems, using the theory of circular turbulent jets. It presents experimental results on the decay of the maximum velocity in the jet for D/d in the range of 5 to 15, where D is the diameter of the chamber and d is the diameter of the jet at the water surface in the diffusion chamber. It was found that when D/d is small [Formula: see text], the decay of the velocity in the jet is appreciably larger than that in a jet in a large stagnant ambient. Key words: jet diffusion, drop shafts, stormwater systems, turbulent flow.

Flow on stepped spillways can be divided into nappe and skimming flow regimes. This technical note presents an approximate method of predicting the characteristics of skimming flow on stepped spillways. Expressing the turbulent shear stress between the skimming stream and the recirculating fluid, trapped by the stream between the steps, in terms of a fluid friction coefficient and dynamic pressure (in terms of the mean velocity), a flow equation has been developed. Using the model studies of Sorensen on the new Monksville dam, this friction coefficient was found to be equal to about 0.18. An estimate has been made of the energy loss caused by the steps and it was found that this loss is significant. It was also found that the skimming flow sets in when the critical depth is greater than about 0.8 times the height of the steps.

This technical note presents the results of a laboratory study of the transition region from the end of a hydraulic jump to fully developed open channel flow. The velocity profile changes from that of a wall jet to the semilogarithmic form of open channel flow. In this region, the bed shear stress continues to decrease rapidly to eventually become constant. The intensity of flow on the centerplane decreases continuously to attain the relevant open channel value. The length of this transition region was found to be approximately equal to 10 times the tailwater depth for the range of Froude numbers studied, which varied from 3.87 to 10.48.

This technical note presents the results of an experimental study on submerged flow over full-width sharp-crested rectangular weirs. Submerged flow was divided into impinging jet and surface flow regimes. A diagram has been developed to predict the occurrence of these regimes. The boundaries of these regimes depend upon the direction of change of the tailwater. A more definitive relation has been developed for the flow-reduction factor for the prediction of discharge for submerged flow.

Abstract This paper presents the results of an experimental study on the transport of fine sand in the entrance region of a progressing cavity pump. The study was performed to provide additional information on the behaviour of the sand slurry flow within a heavy oil well. Tests were carried out with both glycerine and water flows, with the addition of sand in the form of slugs or as a continuous feed to form a sand slurry. Several geometries of the pump intake were used. The different flow regimes observed suggest modes of operation of heavy oil wells that may be used to better avoid sanding or shutting in of wells. These results, in addition to being useful to industry, should also inspire more theoretical studies to explain the formation of the various flow features. Introduction The flow in a heavy oil well consists of a mixture of very viscous heavy oil, gas, water, and fine sand. For these wells, sand production can be a costly problem(1). Within the pump entrance area, there is potential for the sand to choke the flow within the well ("sanding") and production equipment. Sand may form bridges or arches within the annulus of the well to reduce flow tothe pump. Sand may also restrict flow at the intake to the pump, which can result in pump damage. It is possible that the problems associated with sand production are so costly that the well does not operate within economic limits, and is subsequently shut in or abandoned. Field monitoring of solids production in heavy oil wells typically classifies sand entrance into the wellbore to be either "continuous," where a reasonably constant value of sand is produced, or "sluggery," where slugs with high sand concentrations enter the wellbore(1). This paper presents the results of a visualization study to investigate the mechanics of slurry flow in a heavy oil well in the area around the entrance of a progressing cavity pump(2, 3). The purpose of the study was to investigate the flow regimes created in the pump entrance area by changes in the flow rate and properties of the sand slurry fed into the well, and to assess the impact of each on sand removal in the area around the pump intake. Both a very viscous glycerine-sand slurry and a water-sand slurry were used in the experiments to examine the effect of fluid viscosity. The transport of sand was observed in a single liquid phase, with the sand added in slug form or as a continuous feed. The study also investigated the effect of the geometry of the pump intake region on sand removal from the area. Several interesting flow phenomena were observed, and are described herein. Experimental Arrangement and Experiments The visualization model, shown in Figure 1, examined a 1.35 m section around the pump entrance and was close in size to typical heavy oil wells in Western Canada.

This is the second and expanded edition of the first edition of "The Hydraulics of Open Channel Flows : An Introduction" first published in 1999 and reprinted in 2001 and 2002.

This rather large book (of 815 pages) presents a very thorough treatment of dimensional analysis and modeling, covering a broad range of engineering fields. Professor Rozsa has written the first chapter on mathematical preliminaries, which contains a brief discussion of matrices, determinants, and systems of linear equations. Chapters 2–5 discuss the formats for physical relations, dimensional systems, and dimensions. Chapter 6 discusses dimensional homogeneity. The structure of physical relations is discussed at great length in Chap. 7. Chapter 8 shows the development of an efficient method for the construction of dimensionless parameters and introduces a few examples from fluid mechanics. Chapter 9 presents several theorems dealing with the transformations of dimensionless parameters. Chapter 10 discusses the number of dimensionless products of variables with illustrative problems. Chapter 11 presents a discussion on the relevancy of the variables, along with some techniques for identifying physically irrelevant variables. The effectiveness of graphical presentation is discussed in Chap. 12, and forms of the dimensionless relations are discussed in Chap. 13 as to whether the relation between the dimensionless parameters is monomial or non-monomial. If such a monomial relation exists, then some arguments are presented to find the exponents in such a relation. Chapter 14 gives some useful rules and guidelines for sequencing the physical variables in a dimensional set. Chapter 15 discusses problems where dimensions other than mass or force, length, and time occur. One interesting problem is the determination of the optimal location density and location patterns for retail shops. Chapter 16 introduces three ideas to reduce the number of dimensionless groups: (i) reducing the number of physical variables, (ii) increasing the number of dimensions, and (iii) fusing the dimensionless parameters. Chapter 17 looks at dimensional modeling, discussing geometric, kinematic, dynamic, and thermal similarities. This chapter also looks at modeling laws for a whole range of problems, including roasting time for a turkey and comfortable walking speeds for humans and dinosaurs. Chapter 18 presents 43 additional applications, dealing with problems such as axial tensions in a rotating ring, the maximum velocity of an electron in a vacuum tube, the buckling load of a hinged column, existence criteria for black holes, the lateral natural frequency of a cantilever, the diameter of a soap bubble, the velocity of collapse of a row of dominoes, and jamming a circular plug into a non-smooth circular hole. The list of references includes 148 items. There are 8 appendices dealing respectively with (i) recommended names and symbols for some physical quantities, (ii) some more important physical constants, (iii) some more important named dimensionless variables, (iv) notes attached to figures, (v) acronyms, (vi) solutions to problems, (vii) proofs of selected theorems and equations, and (viii) a blank modeling data table. There is also a subject index followed by a surname index. Appendix 3 includes dimensionless numbers such as Beaufort number, Nusselt number, Fourier number, Gratz number, Grashof number, Peclet number, Prandtl number, Rayleigh number, Reynolds number, Schmidt number, Stanton number, Cowling number, Euler number, Froude number, Hartman number, Knudsen number, Strouhal number, Weber number, Snellen number, Mach number, and Cauchy number. This is indeed a rigorous treatment of dimensional analysis, covering vast areas of engineering and physics. Reading the book, one is continuously touched by the contagious enthusiasm and intriguing insight of the author and is entertained by so many interesting anecdotes, quotations, and amusing problems. The treatment of the different topics is very thorough. This reviewer teaches and works in the areas of fluid mechanics and hydraulic engineering and uses dimensional analysis and hydraulic modeling in his work and enjoyed reading this book. Generally, undergraduate students in civil engineering, in their course in fluid mechanics, are introduced to dimensional analysis and then study the principles of hydraulic modeling. Most texts in fluid mechanics have a chapter dealing with these two topics and as such a book like this is perhaps not suitable for them. Even graduate students might find this book far too extensive. But researchers and engineers might find all kinds of interesting problems in this book and as such would benefit from studying this book. This book would be an excellent addition to engineering libraries and consulting offices.

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This paper presents the results of an exploratory study on the development of clear-water scour near a simple groyne-like structure. The growth of the maximum depth of scour with time has been found to be similar. Further, the characteristics of the scour hole in the end state have also been found to be similar. Some simple correlations have also been developed for predicting the maximum depth of clear-water scour in the end state for a narrow range of the relative width parameter.

This paper presents the results of an experimental study of the properties of the bound vortex system housed in a circular jet issuing perpendicularly into a crossflow for three values of the ratio of the jet to crossflow velocity equal to 2.73, 4.52 and 7.05.