Knowledge Of Fluid Mechanics Research Articles

Study of the influence of rheological parameters on the behavior of a submarine debris flow

Submarine debris flows are events that occur with great frequency on a geological scale and can cause major damage to offshore structures or even loss of human life. Understanding the mechanisms involved in the development of a debris flow requires not only knowledge of soil mechanics, but also knowledge of fluid mechanics, since the incorporation of water during the flow causes changes in shear strength. Unlike soils, the shear strength of fluids is represented by mathematical models called rheological models. The objective of this paper is to propose a new rheological model capable of representing the changes caused by water entrainment into a submarine debris flow, by correlating it with the Liquidity Index of the soil. A rheological analysis of marine clay samples from the pre-salt layer has made it possible to represent the variation in strength due to water content. The influence of water content and velocity on flow behavior has also been studied through the analysis of centrifuge tests performed in a previous study.

Undergraduate Student Interest and Knowledge of Fluid Mechanics: A Humanizing Approach to Engineering Concepts

Undergraduate Student Interest and Knowledge of Fluid Mechanics: A Humanizing Approach to Engineering Concepts

Seismic Performance of Building Structures Using Structural Integral Mechanics Model under the Guidance of Fluid Mechanics

The purpose is to study the core causes of serious collapse of buildings damaged in the earthquake and improve the seismic performance of buildings to reduce casualties. First, the theoretical overview of seismic engineering and related form and requirements of the building structure are deeply studied. Next, the building node structure is deeply analyzed according to the knowledge of fluid mechanics and the basic idea of the finite element method of integral structure. The seismic performance of building structures and the principles and requirements of seismic engineering are analyzed and summarized. It is found that the concrete analysis and description of seismic performance in the research method of fluid mechanics is a steel structure’s bending resistance, deformation and displacement degree, and the bearing degree of external impact force. Further, the model design of the integral structure is carried out through the finite element idea of fluid mechanics. Then, the model simulation experiment is conducted to obtain the curve of the impact force on the building structure, the ultimate bearing capacity of the steel beam joint and the skeleton displacement under the impact. Meanwhile, the degradation of stiffness and strength of node structure during an earthquake is analyzed. Finally, through the simulation results, it is concluded that the maximum displacement between node members under the action of impact force is no more than 300mm, so the model has high impact bearing capacity and strong seismic capacity, and can meet the requirements of seismic fortification. This exploration will be of great significance to the development of building seismic engineering under the guidance of fluid mechanics.

Development and evaluation of a virtual simulation experiment system for the course of fluid mechanics

Fluid mechanics is a fundamental course in many disciplines such as civil engineering and hydraulic engineering, with broad applicability and practical significance in engineering. However, the abstractness and multiplicity of its basic concepts hinders students’ first-hand experience during traditional classroom learning, and the time and space limitation of its offline experiment often results in unsatisfying teaching effectiveness. To address these challenges, a set of virtual simulation experiment system is developed for the course of fluid mechanics, along with an external support system to maximize its performance. Evaluation based on curriculum objective achievement shows that this experimental system has significantly improved the teaching effectiveness for the course of fluid mechanics. It promotes students’ independent learning skills and their ability utilizing fluid mechanics knowledge to understand, simplify and solve practical engineering problems.

A Preliminary Study on Integration of Ideological, Political Courses into Fluid Mechanics Course

It is important to take ideological and political course in current universities. An urgent problem exists among college teachers is how to impart professional knowledge to college students with guiding them to recognize the world and themselves in the right path. According to the characteristics of the basic courses and the characteristics of teaching methods in mechanical engineering, this paper takes fluid mechanics as an example to analyze how to excavate the ideological and political elements from the course. In order to improve students' interest in learning and master the professional knowledge, promote the affinity of ideological and political education, and help students recognize the world and themselves softly, this paper analyze the method of combining the professional knowledge of fluid mechanics with moral education skillfully.

A fast method to predict the transient, subcritical gas discharge from a pressure vessel

Based on the Bernoulli’s equation a fast and accurate model is developed to predict the transient gas discharge from a pressure vessel. The system is considered adiabatic, isentropic, compressible, and subcritical and the gas is considered ideal. Based on an energy balance, a simplified method is presented to check whether the system can be assumed to be adiabatic. The opening of the vessel should be at least five outlet diameters D2 away from the other walls or corners in order to fulfil the assumption that the flow velocity inside the vessel is negligible. The model is compared with CFD simulations, which are performed with ANSYS CFX©. Furthermore, a new dimensionless number is introduced, which takes into account the gas and vessel properties. In combination with the developed discharge model and a conducted parameter study, a universal correlation for estimating the discharge duration is developed. The application does not require any further knowledge of fluid mechanics, making it a quick estimation tool for everyone. The model is able to calculate isentropic cooling and the resulting transient behaviour with a deviation from the simulation of <12%. The model and the correlation for the dimensionless number are able to capture the discharge behaviour of any gases and vessels that meet the requirements listed above. The correlation is a fast and accurate tool for estimating safety problems in process engineering.

How to Choose a Shunt for Patients with Normal Pressure Hydrocephalus: A Short Guide to Selecting the Best Shunt Assembly.

Most patients with hydrocephalus are still managed with the implantation of a cerebrospinal fluid (CSF) shunt in which the CSF flow is regulated by a differential-pressure valve (DPV). Our aim in this review is to discuss some basic concepts in fluid mechanics that are frequently ignored but that should be understood by neurosurgeons to enable them to choose the most adequate shunt for each patient. We will present data, some of which is not provided by manufacturers, which may help neurosurgeons in selecting the most appropriate shunt. To do so, we focused on the management of patients with idiopathic “normal-pressure hydrocephalus” (iNPH), as one of the most challenging scenarios, in which the combination of optimal technology, patient characteristics, and knowledge of fluid mechanics can significantly modify the surgical results. For a better understanding of the available hardware and its evolution over time, we will have a second look at the design of the first DPV and the reasons why additional devices were incorporated to control for shunt overdrainage and its related complications. We try to persuade the reader that a clear understanding of the physical concepts of the CSF and shunt dynamics is key to understand the pathophysiology of iNPH and to improve its treatment.

Developing a mobile application‐based particle image velocimetry tool for enhanced teaching and learning in fluid mechanics: A design‐based research approach

AbstractA robust and intuitive understanding of fluid mechanics—the applied science of fluid motion—is foundational within many engineering disciplines, including aerospace, chemical, civil, mechanical, naval, and ocean engineering. In‐depth knowledge of fluid mechanics is critical to safe and economical design of engineering applications employed globally everyday, such as automobiles, aircraft, and sea craft, and to meeting global 21st century engineering challenges, such as developing renewable energy sources, providing access to clean water, managing the environmental nitrogen cycle, and improving urban infrastructure. Despite the fundamental nature of fluid mechanics within the broader undergraduate engineering curriculum, students often characterize courses in fluid mechanics as mathematically onerous, conceptually difficult, and aesthetically uninteresting; anecdotally, undergraduates may choose to opt‐out of fluids engineering‐related careers based on their early experiences in fluids courses. Therefore, the continued development of new frameworks for engineering instruction in fluid mechanics is needed. Toward that end, this paper introduces mobile instructional particle image velocimetry (mI‐PIV), a low‐cost, open‐source, mobile application‐based educational tool under development for smartphones and tablets running Android. The mobile application provides learners with both technological capability and guided instruction that enables them to visualize and experiment with authentic flow fields in real time. The mI‐PIV tool is designed to generate interest in and intuition about fluid flow and to improve understanding of mathematical concepts as they relate to fluid mechanics by providing opportunities for fluids‐related active engagement and discovery in both formal and informal learning contexts.

Application of Knowledge of Fluid Mechanics in the Field of Design of Forming Tools

The paper deals with the construction of a hydrostatic molding tool. The theoretical part presents the necessary knowledge about forming in liquid media. The experimental part presents the construction of a forming tool for drawing using a liquid. The discussion deals with environmental constraints of production processes.

The principle and applications of Bernoulli equation

Bernoulli equation is one of the most important theories of fluid mechanics, it involves a lot of knowledge of fluid mechanics, and is used widely in our life. This paper comprehensives the research present situation of Bernoulli equation at home and abroad, introduces the principle of Bernoulli equation and some applications in our life, and provides direction of the application for the future.

On the development of a fast modeling of floodwater effects on ship motions in waves

The motions of a flooded ship in waves are difficult to evaluate. They are affected by complex phenomena involving ship and floodwater dynamic interactions. Several numerical methods have been proposed to estimate the dynamic behavior of a damaged ship in waves. In this article, a fast simulation tool is developed to tackle the problem, aiming at a simplified method with an acceptable accuracy of the results. A novel approach in simulating floodwater effects on ship motions is presented. The method allows modeling the floodwater motions (seen as lumped mass) out of phase from ship motions. This technique is based on the basic fluid mechanics knowledge for a liquid in a uniformly accelerated tank. The study intends to analyze the behavior of a flooded ship in regular beam waves, for compartment fillings that involve shallow and intermediate fluid depths. The nonlinear model for the roll damping moment of a ship is implemented. An attempt to model viscous effects in the floodwater dynamics is proposed and applied. Two sets of applications are carried out on two different hull models. The comparisons of the intact and of the flooded ship responses in waves are conducted and discussed.

Bubble generated turbulence and direct numerical simulations

Gas–liquid two phase flows are widely encountered in industry. The design parameters include two phase pressure drop, mixing and axial mixing in both the phases, effective interfacial area, heat and mass transfer coefficients. Currently, there is a high degree of empiricism in the design process of such reactors owing to the complexity of coupled flow and reaction mechanism. Hence, we focus on synthesizing recent advances in computational and experimental techniques that will enable future designs of such reactors in a more rational manner by exploring a large design space with high-fidelity models (computational fluid dynamics) that are validated with high-fidelity measurements (hot film anemometry (HFA), Laser Doppler anemometry (LDA), particle image velocimetry (PIV), etc.) to provide a high degree of rigor. Understanding the spatial distributions of dispersed phases and their interaction during scale up are key challenges that were traditionally addressed through pilot scale experiments, but now can be addressed through advanced modelling.For practically complete knowledge of the fluid mechanical parameters, it is desirable to implement direct numerical simulations (DNS). However, the current computational power does not permit full DNS for real bubble columns. Therefore, we have been using simplified turbulence models (such as large eddy simulation, Reynolds stress, k–ε, etc.) which need the knowledge of turbulence parameters. For the estimation of these parameters, currently semi-empirical procedures are being used pending the knowledge of turbulence. Further, the formulation of governing equations in all the CFD models (except DNS), the knowledge of interface forces (drag, lift, virtual mass, Basset, etc.) is needed and for their estimations empirical correlations are being employed, again pending the knowledge of fluid mechanics under turbulent conditions in bubble columns.In gas–liquid dispersions, the gas is sparged in the form of bubbles. During the bubble rise, the mechanism of wake detachment creates turbulence which can be called as wake generated turbulence. In addition, energy gets transferred from the gas phase to liquid phase. The quantitative amounts are negligible when bubble motion is not hindered and the gas–liquid dispersion is homogenous. The amounts increase with an increase in the extent of hindrance. However, in the homogenous regime, even under extreme conditions, the extent of energy transfer in the bulk gas–liquid dispersions (volume other than wake volume) is fairly limited. On contrast, in the heterogeneous regime, the rates of energy transfer become sizeable. The energy received by the liquid (in both the regimes) also creates turbulent motion and termed as bulk generated turbulence. In turbulent flows a compendium of eddies (flow structures) of different length and time scales contribute towards improved/enhanced mixing, momentum transfer, heat transfer, and mass transfer (transport phenomena). Hence, a proper understanding of the dynamics of these turbulent flow structures, and their role in the transport phenomena, can bring substantial improvement in the scale-up and design procedures. The present paper brings out the current status of knowledge on bubble generated turbulence. All the published literature in experimental measurements and DNS simulations has been critically analysed and coherently presented.

The Concept and the Contents of Process Fluid Mechanics

Fluid mechanics is the mechanics of fluids, concerned with the motion of fluids and the forces associated with that motion. A Process is a series of operations which produce a physical or chemical change or biotransformation in the nature of a material. Process industries are those industries in which processes have been taken placed. Process engineering stems from chemical engineering, having much wider ranges and much deep content, and focusing on the design, operation and maintenance of process in process industries. Process fluid mechanics may be interpreted as the fluid mechanics related to process industries and/or process engineering, or as the fluid mechanics used for the process industries or process engineering, or as the knowledge of fluid mechanics should be mastered by the process engineers and process researchers or process scientists. Process fluid mechanics can be divided into physical process fluid mechanics, chemical process fluid mechanics, and biological process fluid mechanics.

Benchmarking for Practical Training in Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) is the useful design tool for engineers that requests strong knowledge of fluid mechanics and numerical skills. Learning by doing has significant impact on the success rate of this difficult subject. This paper presents a workshop developed for engineering degree where different scaled down projects is accomplished by students and peers evaluated. Students improve their understanding of the strong and weak points of the numerical models and gain an insight into the fluid dynamics processes learnt in the classroom. Beside, other transversal skills are developed such as critical thought and collaborative work.

Natural Gas Transmission Pipeline Temperature Drop Calculation

The numerical computation of natural gas pipeline temperature drop will provide the reference data for the design of gas pipeline, the judgement of hydrate formation, the normal production and operation. On the basis of Suhuofu formula, considering the effect of the Joule-Thomson, according to the natural gas flowing through a pipe heat conduction basic theory, combined with engineering thermodynamics, heat transfer and fluid mechanics knowledge, establishing gas transmission pipeline temperature drop model, adopt iterative method, the natural gas temperature along the pipe is calculated, comparing some kind of factors such as gas composition, the pipeline operational factor, the heat preservation situation, and analysis how the factors influent the temperature drop, providing the theory basis for how to reduce the temperature drop in the gas line, the heating power and the heating furnace heating temperature calculation, and energy conservation and optimization. Key words: Natural gas; Temperature drop calculation; Gas line

Natural Gas Transmission Pipeline Temperature Drop Calculation

The numerical computation of natural gas pipeline temperature drop will provide the reference data for the design of gas pipeline, the judgement of hydrate formation, the normal production and operation. On the basis of SuHuoFu formula, considering the effect of the Joule-Thomson, according to the natural gas flowing through a pipe heat conduction basic theory, combined with engineering thermodynamics, heat transfer and fluid mechanics knowledge, establishing gas transmission pipeline temperature drop model, adopt iterative method, the natural gas temperature along the pipe is calculated, comparing some kind of factors such as gas composition, the pipeline operational factor, the heat preservation situation, and analysis how the factors influent the temperature drop, providing the theory basis for how to reduce the temperature drop in the gas line, the heating power and the heating furnace heating temperature calculation, and energy conservation and optimization. Key words : Natural gas; Temperature drop calculation; Gas line

Book Review: Unsteady Combustor Physics

Combustion dynamics is a subject that has been studied for several decades that started due to the requirements of aerospace industries. But in recent times, instabilities that accompany techniques like lean premixed combustion adopted in land-based applications also have reinforced the interest of the combustion community in this area. Thus this area is becoming a major area of combustion research. However, working in this subject requires knowledge of a number of disciplines apart from combustion, which makes initiation into the area of combustion dynamics rather challenging for a beginner. Traditionally, in studies of combustion instabilities, the role of acoustics have received the major attention primarily because of the strong coupling that exists between acoustic disturbances and heat release rate fluctuations and the catastrophic influence that this coupling can have on the performance and even structural integrity of the combustion systems. The current research trend, however, looks beyond thermoacoustics and critically investigates the roles of various factors like flow dynamics, combustion chemistry, heat and species transport to name a few. It is in this context that the utility of the present book under review has to be assessed. The book is designed as an advanced level textbook and gives a broad overview of the various factors that play major roles in combustion dynamics. As stated by the author in the “Preface” the book requires prior knowledge of fluid mechanics and combustion but no prerequisite in acoustics. The first part of the book (Chapters 1 to 6) introduces the basic concepts of reacting flow, hydrodynamic stability and acoustic wave propagation. Starting from general introductions to the subjects, the chapters bring out topics that are directly relevant to combustion dynamics. The second part of the book (Chapters 6 to 12) deals with interactions of these three subjects that are observed in combustion dynamic problems. The first chapter gives a very concise but useful coverage of the basics of transport phenomena in reacting flows. Although primarily of recapitulative nature, the treatment International journal of spray and combustion dynamics · Volume .6 · Number . 2 .2014 – pages 221 – 223 221

Closure to “Discussion on ‘Damping and Inertia Coefficients for Two End Sealed Squeeze Film Dampers With a Central Groove: Measurements and Predictions,’” (2013, ASME Paper No. GT2013-94273).

The authors thank Professor Mihai Arghir for having performed the computational fluid dynamics (CFD) simulations of the flow fields for the two test damper configurations. The predictions demonstrate, as expected, the flow field in the deep feed groove and lubricated through feed holes to be extremely complicated. The brief discussion on the evolution of the flow patterns (vortices) along the various planes of observation is most enlightening.As per the question, “how can the magnitude of the groove effective depth be objectively selected knowing that the flow field is so complex?” the authors concur with Dr. Arghir's judgment, that is, one cannot ascertain the effective groove depth from simple knowledge of fluid mechanics. The effective depth depends not only on the geometry of the groove and adjacent film land but also on the lubricant properties and the operating conditions. That is, as stated in the original development analyses of Refs. [19,20] from the discussion, the effective groove depth is an empirical parameter to be determined from matching experimental results to predictions or extracted from a careful assessment of numerical predictions obtained from complete CFD simulations.An example of the first instance is offered by the current paper where the effective depth is obtained from correlating (only) one experimental parameter, namely a force coefficient, to predictions obtained by continuously varying the groove depth when solving the extended Reynolds equation for a centered journal condition. References [26,27] from the discussion and Ref. [1] offer full details on the matching procedure and note the good agreement of predictions to the experimental results for most off-centered or eccentric journal conditions, small to large orbit radii, and multiple frequencies.Recent CFD research [2,3] demonstrates, as Professor Arghir has done, the complexity of the flow field in even simple squeeze film dampers. Most importantly; however, is for the damper practitioner to realize that classical lubrication theory, which regards a feed groove as a region of stagnant fluid and impervious to the kinematics of journal motion, is plain wrong.The authors express their sincere gratitude to Dr. Arghir. In this time and age where everyone is so busy, having taken the time to understand and to enlighten the work of others is a rarity—a demonstration that someone cares. Discussions to published papers are nowadays an unfortunate anachronism.

The Force State Analysis of the Service Door on an Airliner

The crew emergency evacuation security system is a life-saving device, the ultimate function of which is to save the life of the aircraft crew in a new regional airliner at high altitude. The system is used to push the service door with translational motion for a suitable distance. Before the system was started, the force state of the service door was got with the fluid mechanics knowledge. When the system was started, after a period of pressure relief time, the aircraft cabin pressure was calculated with the Bernoulli's Equation. The movement trajectory and the force state of the service door were obtained by the computational fluid dynamics theory and numerical simulation method. All of the above work must lay a theoretical foundation for the development of the crew emergency evacuation security system, and ensure the flight safety.

Frenagem de um projétil em um meio fluido: “Qual seria a distância, dentro da água, percorrida por um projétil calibre .50 com massa de 50 g e velocidade de 850 m/s?”

A simple model is developed, for the stopping that a projectile with initial speed of hundreds of meters per second undergoes in the water. The model involves knowledge of Fluid Mechanics and Mathematics, at the student level from General Physics course. Empirical evidences which corroborate the counterintuitive predictions of the model are presented.