scholarly journals EXPERIMENTAL MODELING OF TSUNAMI BORE IMPINGEMENT ON A SIMPLIFIED COASTAL BUILDING

2018 ◽  
pp. 43
Author(s):  
Wei-Liang Chuang ◽  
Kuang-An Chang ◽  
James Kaihatu ◽  
Rodrigo Cienfuegos ◽  
Cyril Mokrani
Keyword(s):  
Tsunami Wave ◽  
Fluid Velocity ◽  
Experimental Studies ◽  
Wave Structure ◽  
Analytical Models ◽  
Comprehensive Investigation ◽  
Image Velocimetry ◽  
Sloping Beach ◽  
The Impact ◽  
Wave Structure Interaction

Numerous laboratory efforts were devoted to improve our understanding to the process of tsunami wave-structure interaction and provide valuable data to validate numerical and analytical models. However, the highly turbulent and multiphase nature of tsunami bores makes the study of their impacts very challenging. Many experimental studies (e.g., Shafiei et al. 2016) employed wave gauges to measure the bore height and estimate the bore front velocity based on shallow water equations. Considering the complexity of the flow and its impact with structures, the conversion between the bore height and the bore velocity is far from straightforward. Therefore, this study attempts to apply the bubble image velocimetry (BIV, Ryu et al. 2005) technique to directly measure the flow velocities during the tsunami bore impact. A tsunami wave, that breaks on a sloping beach, propagates inland as a form of bore, and impinges on a rigid structure, is considered as the scenario of interest. The objective is to perform a comprehensive investigation on the borestructure interaction by examining the fluid velocity, impact pressure, and surge force during the impact event with various structure headings.

Simplified Predictive Model for Downhole Pressure Surges During Tripping Operations Using Power Law Drilling Fluids

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Shwetank Krishna ◽  
Syahrir Ridha ◽  
Pandian Vasant ◽  
Suhaib Umer Ilyas ◽  
Titus Ntow Ofei
Keyword(s):  
Experimental Data ◽  
Power Law ◽  
Fluid Velocity ◽  
Industrial Applications ◽  
Considerable Effect ◽  
Analytical Models ◽  
Fluid Loss ◽  
Drilling Fluids ◽  
Minor Effect ◽  
The Impact

Abstract Surge/swab pressure is a crucial parameter that provokes well-control problems such as fluid loss, fractured formations, fluid influx, and kick. Thus, a precise estimation of differential pressure is required to evade any unforeseen drilling difficulties. The existing predictive models are based on narrow-slot approximation methods and consider the effect of drilling string axial movement on downhole pressure surges. However, it ignores the impact on the boundaries of the annular fluid velocity zone by the tripping velocity. In this research, a simplified model is developed using the flow velocity profile generated in the annulus by the tripping operation and the concentric annular Couette fluid flow phenomena for power-law fluid. A comparative study is performed with the existing analytical models and the experimental data to validate the developed model. The obtained results are convincingly in good agreement with the analytical and experimental data. A parametric study is performed to identify the effect of various parameters on surge/swab pressure. It is found that the diameter ratio has a significant impact on pressure differential with the increase in the tripping velocity. The fluid behavior index exhibits a considerable effect, and fluid consistency index shows a minor effect on the surge pressure gradient. The simplified developed model requires less numerical analysis to determine the outcomes for varying industrial applications, especially petroleum drilling operations.

Investigation of Engine Distortion Interaction

2016 ◽  
Author(s):  
Fabian Wartzek ◽  
Heinz-Peter Schiffer ◽  
Jakob P. Haug ◽  
Reinhard Niehuis ◽  
Martin Bitter ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Studies ◽  
Stability Limit ◽  
Analytical Models ◽  
Test Case ◽  
Transonic Compressor ◽  
Numerical Studies ◽  
Small Distortion ◽  
The Stability ◽  
The Impact

Inflow distortions in the compression system of a jet engine are becoming increasingly important for research focus. The investigation of the emergence of a distortion, its interaction with the rotor and the resulting impact on the rotor flow is challenging. In this work a separation in the inflow of a transonic compressor was created and the impact on stage aerodynamics investigated. The separation resulted in a total pressure distortion close to the casing within a sector of 120°. Effects were studied both numerically and experimentally in a joint collaboration project. The numerical model consisted of the full rotor-stator compressor stage, the inlet duct and the distortion generator upstream of the stage. This enables both an accurate validation of the numerical results and contributes to a deeper understanding of the flow. The results of both the numerical and experimental studies were in good agreement. The rotor is locally throttled by the inlet separation, resulting in the formation of an additional loss core at the stability limit due to a local aerodynamic overload. Considering classic distortion descriptors like the DC60, it is shown that they are not able to adequately assess the impact of a strong, but small distortion close to the tip of the rotor. The data can be considered as test case for future numerical models as well as for the validation of new analytical models. Furthermore, the results of this study reveal effects in both experimental and numerical studies that would not be realized if only a model of the separation was analyzed.

Effect of Non Uniform Out-of-Plane Illumination and Shear Rate on the Accuracy of nPIV Velocity Measurements

2010 ◽  
Author(s):  
Rana G. Khader ◽  
Reza Sadr
Keyword(s):  
Fluid Velocity ◽  
Brownian Diffusion ◽  
Bias Error ◽  
Nano Particle ◽  
Shear Rates ◽  
Image Velocimetry ◽  
Out Of Plane ◽  
Fluid Convection ◽  
Particle Images ◽  
The Impact

Nano-particle image velocimetry (nPIV) uses evanescent-wave illumination to measure two velocity components, U and V, tangent to the wall in a region with thickness of order of hundred nano meters. In this region the illumination intensity decays exponentially with distance normal to the wall, z, and hence tracers closer to the wall have “brighter” and “bigger” images than those that are further away, i.e. at larger z. Moreover fluid velocity varies in this region with z and hence tracers at different distance from the wall move at different speeds. Furthermore, Brownian displacement of particle tracers in this region is comparable to the displacement due to the fluid convection. The variation in the displacement of particle images in this region, with different brightness and velocities, can bias the near-wall velocities obtained using standard correlation based PIV method. Artificial nPIV images of nano particle in a flow field with linear out of plane velocity profile were used in this work to investigate the impact of these issues upon the accuracy of nPIV data. Uniform and Gaussian random distribution noise were added to the images to simulate electronic noise and shot noise, respectively. The artificial images were obtained and processed for various experimental parameters to incorporate different illumination profile and shear rates. The results demonstrate that non-uniform illumination affects the bias in the estimated tracer velocity for the shear flow. Non-uniform intensity also affects the bias due to Brownian diffusion; however, correction for Brownian diffusion can reduce this bias error.

Prediction of Wave Impact Pressures on Horizontal Plate

2010 ◽  
Author(s):  
Yanqiu Meng ◽  
Guoping Chen ◽  
Shichang Yan
Keyword(s):  
Wave Length ◽  
Wave Structure ◽  
Impact Pressure ◽  
Detailed Knowledge ◽  
Wave Impact ◽  
Wave Condition ◽  
Model Studies ◽  
Wave Induced ◽  
The Impact ◽  
Wave Structure Interaction

An optimal design of deck of jetty, platform and similar ocean structures requires detailed knowledge on wave impact pressure which affects its function. Investigations on wave induced impact pressures on deck were carried out by using physical model studies. The influences of wave and structure parameters on wave impact pressures were investigated. It is found that the wave impact pressure increases with increased deck clearance. The increasing trend continues up to the relative deck clearance Δh/η = 0.3–0.8, and then the impact pressure starts to decrease after that deck clearance. The wave steepness has some effect on the wave impact pressure, but the trend of variation is not consistent for different wave condition. The maximum impact pressure occurs when the ratio of wave length to deck width equals 3.97. Increase of wave period results in increase of the distance between the location of the maximum impact pressure and the seaward end of deck. Based on analysis of the physics of the wave structure interaction, empirical formula was proposed to estimate wave impact pressure on deck.

Application of Breather Solutions for the Investigation of Wave/Structure Interaction in High Steep Waves

2012 ◽  
Author(s):  
Günther F. Clauss ◽  
Marco Klein ◽  
Matthias Dudek ◽  
Miguel Onorato
Keyword(s):  
Real World ◽  
Wave Structure ◽  
Model Tests ◽  
Design Stage ◽  
Regular Waves ◽  
Freak Waves ◽  
Structure Interaction ◽  
Steep Waves ◽  
The Impact ◽  
Wave Structure Interaction

During the design process of floating structures, different specifications have to be aligned such as the range of application, the warranty of economical efficiency as well as the reliability and are an inevitable integral part of the evaluation process during the design stage. The validation of the performance by means of model tests in terms of sea state behavior and the associated local and global structural loads are an important milestone within this process. Therefore it is necessary to determine an adequate test procedure which covers all essential areas of interest. Thereby one field of interest are limiting criteria of the design such as maximum local and global loads as well as maximum accelerations due to the impact of extraordinarily high waves, at which the floating structure has to survive. Different alternatives are available to conduct model tests in high, steep waves — transient wave packages, regular waves, irregular waves with random phases or more sophisticated deterministic tailored irregular wave sequences such as reproductions from numerical simulations and real-world measurements. This paper introduces a new approach for the systematic investigation of wave/structure interaction in high, steep waves. Exact solutions of the nonlinear Schrodinger equation — the so called breather solutions — are implemented for the generation of extraordinarily high waves. Three types of breather solutions are investigated in the seakeeping basin and to cover the full range of interest, each solution has been used to generate freak waves at certain frequencies. To evaluate the applicability of breather solutions for model tests two types of ships — a LNG Carrier and a Chemical Tanker — are investigated in the seakeeping basin. The ships are segmented and connected with strain gauges to detect the vertical wave bending moment. Furthermore, green water probes are installed on deck to evaluate the local impact on the bow of the freak waves. The obtained results are compared to investigations in regular waves with certain frequency and steepness as well as in real-world freak wave reproductions.

scholarly journals A Procedure to Calculate First-Order Wave-Structure Interaction Loads in Wave Farms and Other Multi-Body Structures Subjected to Inhomogeneous Waves

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1761
Author(s):  
José Miguel Rodrigues
Keyword(s):  
Wave Field ◽  
Experimental Studies ◽  
Wave Structure ◽  
Linear Potential ◽  
Interaction Method ◽  
Structure Interaction ◽  
First Order ◽  
Inhomogeneous Waves ◽  
Multi Body ◽  
Wave Structure Interaction

A typical assumption when performing analytical, numerical, and experimental studies in wave–structure interaction in multi-body problems such as for wave farms and very large floating structures is the homogeneity of the wave field. Important interactions between the floating elements are dependent on the direction, amplitude, and phase of the waves acting on each. Then, wave homogeneity is probably unrealistic in near-shore areas where these installations are to be deployed. In the present work, an existing interaction method, which allows the use of standard boundary element diffraction codes for solving the first order wave structure linear potential for each unique geometry in the problem, is shown to be able to account for inhomogeneous sea states across the domain of a multi-body problem requiring only minimal modification to its implementation. A procedure to use the method to include arbitrary incoming undisturbed wave conditions at each body is presented. A verification study was done by using an artificial numerical configuration to mimic an inhomogeneous wave field in a standard diffraction code, which was used as a reference. The results obtained using the interaction-method based procedure are shown to be in excellent agreement with the reference ones. Furthermore, an example of frequency inhomogeneity of the wave field in a wave farm is shown and the effects on the motion amplitudes and absorbed power are presented illustrating the applicability of the procedure.

Воздействиеультразвуковогополянадинамическуювязкостьводы

2019 ◽  
pp. 27-29
Author(s):  
P. Vikulin ◽  
K. Khlopov ◽  
M. Cherkashin
Keyword(s):  
Dynamic Viscosity ◽  
Experimental Studies ◽  
Ultrasonic Field ◽  
Maximum Effect ◽  
Ultrasonic Frequency ◽  
Ultrasonic Vibrations ◽  
Wastewater Disposal ◽  
Laboratory Setup ◽  
Sonic Treatment ◽  
The Impact

Enhancing water purification processes is provided by various methods including physical ones, in particular, exposure to ultrasonic vibrations. The change in the dynamic viscosity of water affects the rate of deposition of particles in the aquatic environment which can be used in natural and wastewater treatment. At the Department Water Supply and Wastewater Disposal of the National Research Moscow State University of Civil Engineering experimental studies were conducted under laboratory conditions to study the effect of ultrasound on the change in the dynamic viscosity of water. A laboratory setup has been designed consisting of an ultrasonic frequency generator of the relative intensity, a transducer (concentrator) that transmits ultrasonic vibrations to the source water, and sonic treatment tanks. Experimental studies on the impact of the ultrasonic field in the cavitation mode on the dynamic viscosity of the aqueous medium were carried out the exposure time was obtained to achieve the maximum effect.Интенсификация процессов очистки воды осуществляется с помощью различных методов, в том числе и физических, в частности воздействием ультразвуковых колебаний. Изменение динамической вязкости воды влияет на скорость осаждения частиц в водной среде, что может быть использовано в процессах очистки природных и сточных вод. На кафедре Водоснабжение и водоотведение Национального исследовательского Московского государственного строительного университета в лабораторных условиях проведены экспериментальные исследования по изучению влияния ультразвука на изменение динамической вязкости воды. Разработана схема лабораторной установки, состоящая из генератора ультразвуковых частот с соответствующей интенсивностью, преобразователя (концентратора), передающего ультразвуковые колебания в исходную воду, и емкости для озвучивания. Выполнены экспериментальные исследования по влиянию ультразвукового поля в режиме кавитации на динамическую вязкость водной среды, получено время экспозиции для достижения максимального эффекта.

Family Influences on Youth Offending

2018 ◽  
pp. 377-403
Author(s):  
Abigail A. Fagan ◽  
Kristen M. Benedini
Keyword(s):  
Life Course ◽  
Family Environment ◽  
Parenting Practices ◽  
Experimental Studies ◽  
The United States ◽  
Parental Violence ◽  
Youth Delinquency ◽  
The Impact ◽  
Children’S Exposure

This chapter reviews the degree to which empirical evidence demonstrates that families influence youth delinquency. Because they are most likely to be emphasized in life-course theories, this chapter focuses on parenting practices such as parental warmth and involvement, supervision and discipline of children, and child maltreatment. It also summarizes literature examining the role of children's exposure to parental violence, family criminality, and young (teenage) parents in affecting delinquency. Because life-course theories are ideally tested using longitudinal data, which allow examination of, in this case, the impact of parenting practices on children's subsequent behaviors, this chapter focuses on evidence generated from prospective studies conducted in the United States and other countries. It also discusses findings from experimental studies designed to reduce youth substance use and delinquency by improving the family environment.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

scholarly journals Anthropomorphic Strategies Promote Wildlife Conservation through Empathy: The Moderation Role of the Public Epidemic Situation

2021 ◽  
Vol 18 (7) ◽  
pp. 3565
Author(s):  
Dan Yue ◽  
Zepeng Tong ◽  
Jianchi Tian ◽  
Yang Li ◽  
Linxiu Zhang ◽  
...  
Keyword(s):  
College Students ◽  
Behavioral Intention ◽  
Wildlife Conservation ◽  
Negative Emotion ◽  
Public Awareness ◽  
Negative Emotions ◽  
Experimental Studies ◽  
Wildlife Trade ◽  
Illegal Wildlife Trade ◽  
The Impact

The global illegal wildlife trade directly threatens biodiversity and leads to disease outbreaks and epidemics. In order to avoid the loss of endangered species and ensure public health security, it is necessary to intervene in illegal wildlife trade and promote public awareness of the need for wildlife conservation. Anthropomorphism is a basic and common psychological process in humans that plays a crucial role in determining how a person interacts with other non-human agents. Previous research indicates that anthropomorphizing nature entities through metaphors could increase individual behavioral intention of wildlife conservation. However, relatively little is known about the mechanism by which anthropomorphism influences behavioral intention and whether social context affects the effect of anthropomorphism. This research investigated the impact of negative emotions associated with a pandemic situation on the effectiveness of anthropomorphic strategies for wildlife conservation across two experimental studies. Experiment 1 recruited 245 college students online and asked them to read a combination of texts and pictures as anthropomorphic materials. The results indicated that anthropomorphic materials could increase participants’ empathy and decrease their wildlife product consumption intention. Experiment 2 recruited 140 college students online and they were required to read the same materials as experiment 1 after watching a video related to epidemics. The results showed that the effect of wildlife anthropomorphization vanished if participants’ negative emotion was aroused by the video. The present research provides experimental evidence that anthropomorphic strategies would be useful for boosting public support for wildlife conservation. However, policymakers and conservation organizations must be careful about the negative effects of the pandemic context, as the negative emotions produced by it seems to weaken the effectiveness of anthropomorphic strategies.

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