Culvert Hydraulics

Review of <i>Stormwater Design for Sustainable Development</i> by Ronald L. RossmillerMcGraw-Hill Professional, New York; 2014; ISBN-10: 0-07-181652-6, ISBN-13: 978-0-07-181652-6; 401 pp.; $44.

The assessment of fish passage through turbines is important to develop cost-efficient environmental solutions and strategies that avoid individual fish injuries and, therefore, enhance the fish population development in a catchment. As part of the FIThydro project, fish passage analysis were performed for the bulb turbine in Bannwil, the S-turbine in Guma and the bulb unit at the test facility in Obernach.Numerical modelling in principle provides the most comprehensive information on hydrodynamic conditions in the turbine passage. Many details of the main relevant stressors on fishes can be derived. The information of different stressors like pressure, strike, shear and turbulence can be extracted with high accuracy assuming that a fish pathway follows a streamline through the turbine. The accurate prediction of the stressors and the validation with measurements enables the designer to develop a turbine that reduces the stress on the fish and, hence, increase the fish survival rate.The survival rate also strongly depends on biological aspects of a fish species. Besides the reaction of the fish on the different stressors, complex parameters like swim behavior or preferred swim elevations are of high importance on the survival rate. However, these parameters vary among different fish species.CFD simulations of different turbines are performed and simulation results were compared to measurements with the Barotrauma Detection System (BDS) sensors at the test cases in Guma and Bannwil, as well as live fish tests at the test facility in Obernach. The fish behavior was modeled in the CFD based evaluation method. Studies related to swimming speed, fish orientation and especially the actual passage location demonstrate the sensitivity of these parameters on the fish survival rate. Another aspect was the influence of operating conditions on fish passage. A wide spectrum of operating conditions was analyzed and fish passage hill-charts for different stressors were generated. This knowledge enables an adapted power plant operation related to migration movements of certain fish species. The CFD based analysis method shows to be a powerful tool to improve fish passage through a turbine by changing hydraulic design and by adapting operational modes. Relative improvements to conventional designs and operation can be quantified.

The terrace type fisliway is a hybrid fishway of the pooi type and the stream type, which has been developed and constructed at a groundsill of River Neo in 2000 by the Upper-Kisogawa construction bureau of the Japanese government and Yamatatsu Construction Company where one of the authors is working. The terrace type fishway is named for its shape that resembles a terrace paddy in a mountainous area. This fishway is equipped with several devices; a) There are many slits on the walls that are surrounding the pools, because the walls are made of the fieldstones around the groundsill. The fishes can pass through the slits without jumping. b) The mouth of the fishway opens widely for fishes to find their routes easily. In addition, the slope for the lateral direction is set steeper than that for the stream direction to gather the river water along the walls, which assures the minimum water depth required for passing even in the drought period. c) The depth of the pools is shallow enough to flush the soil and sands during the flood, which makes the fishway maintenance-free. d) The roughness with small rocks on the slits and bottom of the pool effectively reduces the velocity in the fishway. e) The rapid velocity at the upstream mouth of fishway is reduced by raising the position of the mouth. The hydraulic characteristics and effectiveness of the fishway from the viewpoint of passage of the aquatic habitats are examined by the follow-up surveys during these 3 years. As a result, it proves that the terrace type fishway can be an alternative to the conventional ones and further it is superior to them in many aspects.

Computational investigation of the tumor position and ambient conditions on magnetic nanoparticle thermo-therapy

The high-level objective of MARS project was to understand the formation and behaviour of turbulent structures which affects the Reynolds stress and skin friction. The aim was, once understood, to apply flow control techniques in order to control these structures and reduce the overall drag derived from the Reynolds stress and mainly from the skin friction. Active flow control devices were the main interest; DBD plasma, Synthetic jets, Micro Blowing and Suction, Moving Surfaces were included on the list. To test all these devices, two test cases were defined, and a database and file repository were established in the project webserver. The present chapter is aimed to describe the test cases, including the set-up of the flow control devices, as well as to describe the file repository were all the data was stored.

A data–driven sensibility tool for flow control based on resolvent analysis

A recent publication by McCargar and Zurk [(2013). J. Acoust. Soc. Am. 133(4), EL320-EL325] introduced a modified Fourier transform-based method for passive source depth estimation using vertical line arrays deployed below the critical depth in the deep ocean. This method utilizes the depth-dependent modulation caused by the interference between the direct and surface-reflected acoustic arrivals, the observation of which is enhanced by propagation through the reliable acoustic path. However, neither the performance of this method nor its limits of applicability have yet been thoroughly investigated. This paper addresses both of these issues; the first by identifying and analyzing the factors that influence the resolution and ambiguity in the transform-based depth estimate; the second by introducing another, much simpler depth estimation method, which is used to determine the target trajectories required for observation of the interference pattern and the array requirements for accurate depth estimation.

RESUMO Diferentes sistemas hidráulicos instalados em barramentos têm sido utilizados como Mecanismos de Transposição de Peixes (MTP’s) e se constituem em uma alternativa para o movimento migratório de peixes para reprodução (“piracema”). A variação da declividade do MTP influencia a extensão do mesmo e consequentemente o custo final do mecanismo. Para determinar a melhor declividade do sistema, é necessário verificar parâmetros que influenciam a migração dos peixes, como campos de velocidades, níveis de dissipação de energia e tensão cisalhante de Reynolds nos tanques além do conhecimento de variáveis biológicas das espécies aquáticas a serem transpostas. No entanto, esses parâmetros não são avaliados conjuntamente, e alguns deles são avaliados pela média do escoamento em todo o tanque. Este trabalho apresenta uma análise dos principais parâmetros hidráulicos em tanque um tanque de um mecanismo do tipo escada com ranhura vertical em duas declividades, 6% e 12%, que se encontram próximo aos limites adotados nesse tipo de projeto. Os mapas dos parâmetros hidráulicos mostram que a declividade de 6% é a mais indicada para o projeto desse tipo de MTP, pois os seus níveis de velocidades, dissipação de energia e de tensão cisalhante de Reynolds são mais compatíveis com as condições ideais para a passagem de peixes. Para a declividade de 12% ocorre limitação de área possível de passagem do peixe devido a dissipação de energia e tensão cisalhante de Reynolds locais.

Barriers resulting from anthropogenic activities (e.g., hydropower development, irrigation, flood control, low flow augmentation) can prevent the upstream migration of fish, reducing the connectivity of river systems. As a result, great efforts have been devoted to the design and installation of engineered fishways to enable the movement of fishes across barriers. However, the literature is generally devoid of scientific papers dealing with fishway design and effectiveness, making it difficult for those developing such facilities to determine which fishway designs are most appropriate for a given system and target species. One approach for providing information to support future fishway development is through the creation of databases that contain detailed accounts of existing facilities. Described here is the development of an engineered fishway database in Canada (called CanFishPass) intended to serve as a repository for information that has previously been difficult to find. The database includes detailed geo-referenced information such as engineering details, hydraulic characteristics, and biological effectiveness of one general class of fish passage facility (i.e., engineered fishways), as well as photographs and design drawings where available. The database is searchable by species, fishway type, and ecozone, and includes a reference section comprised of both peer-reviewed and grey literature. It is anticipated that the database will serve as an important resource for future fishway development projects enabling quantitative analyses, while also serving as the first inventory of engineered fishways in Canada. Although our efforts to date have been focused on Canada, the expansion to a global inventory of fishways would enable opportunities to learn directly from facility operations in other regions.

The objective of this research is mutual validation of computational analysis and experimental measurements of baseline and controlled flow over a blunt configuration. A rectangular wing with a 36 percent thick airfoil was selected as a test case, representing a rotor pylon fairing. However, the results are relevant to thick airfoils in general, and contribute to the study of turbulent boundary layer separation and control. Despite the apparently simple geometry, previous measurements on this NACA 0036 airfoil proved challenging for computational analysis. Computational analysis, using DES, provided accurate prediction of the the massive separation and the effects of the oscillatory flow control. Both the aerodynamic coefficients variation with angle of attack, and the pressure distribution on the wing were in good agreement with measurements. These results stand in contrast to the previous failure of incompressible RANS solutions to reproduce the massive separation, its effect on aerodynamic coefficients, and the impact of flow control from t different slots.

This paper investigates the dynamic internal flow structure, and its outlet jets, of the fluidic oscillator. The objective of this numerical study is to provide a better understanding of this type of jet for a research domain aimed at improving various aspects of fluid flow control. The present work focuses on the two-output fluidic oscillator, which involves no moving parts in direct contact with the flow. An analysis of the internal and external dynamics of the two-output fluidic oscillator using numerical simulations for compressible air flow was investigated by employing the SST turbulence model. The study highlights the periodic oscillation of the jet inside the fluidic oscillator between the two branches driven by the Coanda effect, which characterizes the oscillatory behavior of the fluidic oscillator. Furthermore, it reveals the importance of controlling the inlet pressure to maintain the oscillatory behavior. The results demonstrate that the outlet velocity is influenced by the inlet conditions as well as the system's geometry. In conclusion, the article provides essential insights into the dynamics of the two-output fluidic oscillator, emphasizing the impact of physical and geometrical control parameters on flow behavior.

The main purpose of the present paper is to demonstrate the importance of air curtains on the likely performance of cold rooms .The paper explores the benefits of using computational fluid dynamics (CFD) as a tool for simulation of the flow and heat transfer characteristics of air curtains in a vertical display case and cold rooms .This can be achieved by using computational fluid dynamics software to simulate the air flow pattern and the temperature distribution in a frozen food vertical display cabinet .Previous research work is analyzed and critically viewed in respect of previous literature reported to predict the sensible heat transfer across the air curtain and using it to investigate the effect of various design parameters such as jet angles and initial velocities on heat transfer . The present work emphasized the importance of the three dimensional modelling of the flow regimes downstream of an air curtain used to restrict cold room infiltration. The present work highlights the significance of using a full three dimensional procedure, using a commercial CFD code Fluent 6.2. and gives examples of comparisons with relevant experimentations. The effect of operating parameters (outlet velocity, temperature and humidity ratio) on the performance of the air curtain is investigated together with the external wind velocity and curtain outlet angle .Few published test cases were used to access the validity of the model assumptions and good agreements with the experiments were generally shown.

We have been developing centrifugal pumps for an implantable left ventricular assist device. We manufactured 2 prototype centrifugal pumps (PI, PII). These two have similar designs except for the PII having a volute casing and a large output port. To determine the differences in the hydraulic characteristics between the PI and PII, we carried out in vitro and in vivo experiments. In vitro study showed that the PII had a shallower H-Q curve than that of the PI, and the PII required a pump speed faster than the PI for the same flow rate and pressure head. On the other hand, in vivo study showed that the PII demonstrated a flow pulsatility greater than that of the PI at 1,900 rpm and 8 L/min although no significant change was observed at low pump speeds (< or = 1,500 rpm). This greater pulsatility consisted of a large discharge according to the small differential pressure during the systolic phase and a small discharge according to the large differential pressure during the diastolic phase. In contrast, the PI, having the steeper H-Q curve, showed a small discharge in the systolic phase and a large discharge in the diastolic phase. These results showed that pulsatility synchronized with the native heart beating depended on the slope of the H-Q curve. As a result, the slope of the H-Q curve is important to determine the component of pulsatility synchronized with native cardiac output. Regarding the slope of the H-Q curve, a pump having a volute casing and a large outlet port demonstrates a shallow slope in the H-Q curve. In conclusion, we suggest that a centrifugal pump for use in left ventricular aortic bypass should be designed considering the effect on the native heart pulsatility.

Classical methods such as limit equilibrium or limit analysis, dealing with the stability analysis of open cuts and trenches and calculation of critical excavation depth for them, do not fully satisfy the theoretical requirements for stability problems leading to di erent solutions depending on the adopted method. It is now appreciated that geomaterials exhibit considerable heterogeneity, caused by the lithological and inherent variation, which cannot be fully covered by simple methods. This paper highlights the uncertainty embedded in critical excavation depth calculation, arising from spatial variability of shear strength parameters, using Random Finite Di erence Method (RFDM) and Random Limit Equilibrium Method (RLEM). In the present study, the lognormally distributed undrained shear strength is considered spatially correlated throughout the domain. Surface cohesion value and the shear strength density were introduced as the deterministic parameters along with the coecient of variation of undrained shear strength and its scale of uctuation as stochastic parameters; these parameters were studied to see their e ect on uncertainty in critical excavation depth estimation. The results clearly demonstrated the uncertainty in critical excavation depth arising from the inherent variability of shear strength parameters using the RFDM results; however, RLEM did not prove to reflect such uncertainty eciently due to local averaging in prescribed failure surfaces.

Practical application of active supersonic flow control is dependent upon the development of robust actuators that have the requisite control authority (in amplitude and frequency), are reliable and low cost and consume minimal power. The Johns Hopkins University Applied Physics Laboratory and Florida State University/Florida Center for Advanced Aero-Propulsion are continuing the investigation of a device intended for highspeed flow control called the SparkJet actuator, which manipulates high-speed flows without active, mechanical components. Previous experimental and computational efforts demonstrate peak cavity pressure efficiency of approximately 30%, while experience has shown difficulty in constructing a reliable device. This body of work addresses SparkJet design modifications to improve performance measures such as device reliability, efficiency and lifetime. Success toward improving these performance-based characteristics has been accomplished by focusing attention to the modification of the trigger mechanism and electrode design. The trigger mechanism has been changed from an external trigger to a pseudo-series trigger which allows for larger electrode gaps up to 4.0 mm corresponding to peak cavity pressure efficiency up to 75%. Electrode design considerations have included parametric studies to observe the effect of varying tip shape, electrode material and electrode design. Increasing electrode diameter improves survivability under high thermal loads; consistent tip shape design maintains control of spark location near the center of the cavity; and proper electrode material selection impacts survivability. Results confirmed that larger electrode diameters up to 3.175 mm improve survivability under the high thermal loads associated with the spark-discharge environment. Preliminary results also indicate that the length-to-diameter ratio of the electrodes should exceed approximately 24 for proper impedance matching at frequencies above 1 kHz. This paper summarizes these findings through presentation of experimental results including microschlieren imagery, cavity pressure measurements and qualitative observations.