Top PDF Bubble Interactions at Multi-Fluid Interfaces

Bubble Interactions at Multi-Fluid Interfaces

Bubble Interactions at Multi-Fluid Interfaces

The motion of bubbles in a liquid medium has captured the attention of scientists and researchers for centuries. Leonardo da Vinci was perhaps the first to scientifically investigate and report on the failure of large bubbles to follow a rectilinear rise path; this finding was later dubbed Leonardo’s paradox [1]. It wasn’t until several centuries after his death that the mystery was solved, and the phenomenon was determined to be a result of wake instabilities. In the early 19 th century, Thomas Young introduced the concept of surface tension in his qualitative studies on the shape of fluid-fluid interfaces under capillary forces [2]. A year later, Pierre-Simon Laplace gave Young’s qualitative theory a mathematical description, and the well-known Young-Laplace equation was derived [3]. Later that same century, Osborne Reynolds analyzed fluid flow in thin films, which resulted in the lubrication equations that are still used extensively today [4]. In more recent years, technological advances have allowed us to explore many of the underlying physics associated with bubble motion and bubble interactions with other surfaces in a liquid medium. Despite the centuries worth of research, many complexities associated with bubble interactions still remain a mystery. The focus of this dissertation is to broach these topics and develop an improved understanding of bubble interactions at multi-fluid interfaces.
Show more

187 Read more

Prediction of Multi-Inputs Bubble Column Reactor Using a Novel Hybrid Model of Computational Fluid Dynamics and Machine Learning

Prediction of Multi-Inputs Bubble Column Reactor Using a Novel Hybrid Model of Computational Fluid Dynamics and Machine Learning

Hoelscher, 1976; Pino et al., 1992; Shah, Kelkar, Godbole, & Deckwer, 1982). In reaction engineering, three-phase bubble column reactors have an extensive application. For instance, to manufacture industrially valuable bioproducts, gas-liquid-solid interaction reactors are the frequency used in biochemical applications (Essadki, Nikov, & Delmas, 1997; Lopez de Bertodano, Lahey Jr, & Jones, 1994; Sokolichin & Eigenberger, 1994). To understand better about complex behavior of mas and heat transfer rate, hydrodynamic characteristics such as gas-liquid interactions, bubble coalescence, and break-up, it is required to investigate design parameters and optimization of the process in bubble column reactors (Dhotre, Ekambara, & Joshi, 2004; Krishna & Van Baten, 2003; Maalej, Benadda, & Otterbein, 2003; S. Wang et al., 2003).
Show more

37 Read more

Application of the Meshless Local Petrov-Galerkin Method to Unsteady, Multi-Dimensional Fluid Dynamics with Interfaces.

Application of the Meshless Local Petrov-Galerkin Method to Unsteady, Multi-Dimensional Fluid Dynamics with Interfaces.

of the governing equations is much less common in fluids research. For this and other reason the fluids community has been slower to explore the method. In this work, common fluids benchmark problems are presented to validate the implementation of the MLPG methodology and to validate the novel SFIM boundary condition. The body of work was expanded through the successful modeling of the Rayleigh-Taylor Instability. This application requires a four-step solution process of the variable density two-dimensional Navier-Stokes equations in primitive variable form. RTI is a immiscible fluid interface problem. A more dense fluid is suspended above a less dense fluid and gravity drives the resulting fluid motion. RTI is characterized the shape that results as the heavy fluid moves downward. In this work RTI was modeled successfully with MLPG using the new SFIM boundary condition. The fluid motion was monitored via a growth rate for both the spike of more dense fluid and the rising bubble of less dense fluid. The growth rate was smooth and compares well qualitatively with existing literature. The contours of density and velocity are smooth with no boundary or numerical artifacts. The modeling of the Rayleigh-Taylor Instability introduces a new class of fluids applications that can be modeled using MLPG.
Show more

124 Read more

Transmission line modelling for multi-gigabit serial interfaces

Transmission line modelling for multi-gigabit serial interfaces

Modern Computer systems increasingly use high-speed multi-gigabit/second (GB/s) serial interconnects in order to transfer data between components, both on board, to daughter cards and across backplanes. Examples of such interfaces as Peripheral Component Interconnect Express (PCI-E), Serial Advanced Technology Attachment (SATA) and Hyper-transport, for reasons of performance these interfaces are invariably implemented as differential signals [Derickson, Muller, 2008].

13 Read more

Multi-fluid Plasma Modelling

Multi-fluid Plasma Modelling

The system of equations obtained in the previous section (Eq. (3.76) to Eq. (6.3) on pages 30–69) is comprised of two algebraic equations and an elliptic partial differential equation. A numerical code for solving this system of equations is implemented as a modification of teh single-fluid code FLOW [5]. In Section 4.1, the numerical techniques used by FLOW to find solutions to this system are described. Section 4.2 details the mechanics of the code FLOW [5] upon which this analysis is built. Section 4.3 then describes the modifications to FLOW that were necessary to solve the system of equations obtained in Chapter 3. Section 4.4 proceeds to give a parameterisation of four of the flux functions in terms of more intuitive functions. Next, Section 4.5 investigates some transformations of the multi-fluid system of equations. Finally, in Sections 4.6 and 4.7, the modified FLOW code is benchmarked against other results to validate the results given by the modified FLOW code.
Show more

85 Read more

SIMULATIONS OF FLUID INTERFACES USING CONSERVATIVE FRONTTRACKING METHOD FOR 2D EULER SYSTEM

SIMULATIONS OF FLUID INTERFACES USING CONSERVATIVE FRONTTRACKING METHOD FOR 2D EULER SYSTEM

Potential flow model describes the amplitude growth rate through the late-time, nonlinear regime by the spike and bubble velocity evolution. Layzer (1955) first studied single-mode potential flow model to compute the bubble velocity for Rayleigh-Taylor case. (Hecht et al, 1994) extended Layzer-type model and studied the bubble velocity for RM-instability corresponding to an Atwood number A=1, which shows the decay of bubble velocity. Their model was applied to two-dimensional single-mode bubble evolution as well as two-bubble competition. Zhang and Sohn also compared their nonlinear theory with that of potential model (Holmes R.S.,1994; Li X. L. & Zhang Q., 1997; Mao De-kang, 2000).
Show more

6 Read more

Fluid Structure Interactions of Inverted Leaves and Flags

Fluid Structure Interactions of Inverted Leaves and Flags

In our natural world, interactions between fluid forces and elastic bodies are ubiquitous. Examples can be seen in leaves that flap and flutter in the wind, or fish that bend and deform for propulsion. In living organisms, the prevalence of fluid-structure couplings over rigid body aerodynamics can often lead to unique dynamical behaviors. Thus, the field of bio-inspired engineering has flourished in recent years as researchers seek inspiration from these uniquely natural phenomena. Much work has concentrated on animal locomotion, from the beating of flagella [1], to the jet-propulsion of jellyfish [2, 3], to the paddling propulsion of ducks [4].
Show more

32 Read more

A meso-scale model for fluid-microstructure interactions

A meso-scale model for fluid-microstructure interactions

LBM is a numerical method based on the microscopic representation of a fluid by a particle distribution function (PDF), discretized in space and time. It evolved from the lattice gas cellular automata approach [17, 18] and is considered an alternative to traditional CFD methods based on direct solution of the Navier-Stokes equations. In its most general form, physical space or the domain of interest is represented by a regular lattice which allocates particles at discrete nodes; the particles are then allowed to move from one node to a neighboring node and may collide with other particles located at those nodes. Since the methodology aims to represent the physics of a real system, the lattice grid where the PDF lies should be sufficiently resolved and the time step small enough to ensure simulation accuracy and stability, and in order to recover the continuum parameters such as density and fluid velocity of the macroscopic system.
Show more

10 Read more

Assessing the effectiveness of multi-touch interfaces for DP operation

Assessing the effectiveness of multi-touch interfaces for DP operation

using gestures versus traditional buttons and menus in a static versus moving environment. Three different prototypes were tested; where the initial was lo-fi and the first iteration of user tests produced the results needed to develop a second prototype where they could be implemented. The 1st generation prototype was software and hardware based and gave the possibility of investigating multi-touch interaction in a static environment through a second user study. This study resulted in interesting and significant results. The feedback from the test participants were taken into account and a 2 nd generation prototype were developed using similar software adapted to fit new and better hardware. Two iterations of user studies were carried out using the 2 nd generation prototype, one pilot study and one larger study. The larger study was the last study in this project that concerned operating a DP system using buttons/menus versus gestures in a static versus moving environment. In addition the participants were distracted in order to keep their focus on both the interface and the surrounding environment. Preliminary analysis of the data seems to indicate that the movement had little to no impact on performance and that using gestures during look-out lead to a more flowing interaction. After generating four different iterations of user studies and testing, it was possible to reveal issues that would have stayed hidden if decisions of selecting hardware and software were taken without utilising these methods of low-cost testing. In addition the results from extensive testing can be reused and used to create guidelines for similar types of problems to be addressed. The limitations of creating several prototypes are however that it is time consuming and often it is not possible to test all conditions to make it as authentic as possible. The other issues that limits the iterative design is that design decisions often made in the very beginning of the design process may be wrong. Dix et al. [Dix et al., 1997] state that when initial decisions are wrong, the design inertia can be so great as never to overcome an initial bad decision. In theory this means that an iterative design will discover changes that need to be made, but in practice there can be bad decisions within the basic design that are not unveiled and dealt with (finding a local minimum, but missing the global one). The other issue is that if a usability problem is diagnosed through testing, it is important to investigate the background of the problem and not only deal with the symptom. It is therefore important when working with an iterative design process to support the process with additional methods and thorough testing.
Show more

13 Read more

An Industrial Fluid Multi-Sensor

An Industrial Fluid Multi-Sensor

Determining oil quality is an important part of any industry that uses oil as lubrication. Over time oil quality degrades with use or from contaminants being introduced. Since the majority of systems that use oil are closed systems there is no way to remove contaminants or recycle the oil to its original state. The only option is to change the oil. Even with frequent oil changes there is still a chance that a contaminant can be introduced, causing a failure. Currently there are sensors that test oil quality, but they are bulky compared to a Microelectromechanical (MEMs) multi-sensor. The objective of this project is to make a low cost industrial fluid multi-sensor to replace larger sensors that exists today. The industrial fluids multi-sensor will measure; oil quality, water in oil and temperature of the oil.
Show more

90 Read more

Enhancing Instructor Student and Student Student Interactions with Mobile Interfaces and Summarization

Enhancing Instructor Student and Student Student Interactions with Mobile Interfaces and Summarization

Our live demo will introduce CourseMIRROR, a mobile application that leverages mobile interfaces and a phrase summarization technique to facili- tate the use of reflection prompts in large class- rooms. CourseMIRROR automatically produces and presents summaries of student reflections to both students and instructors, to help them capture the difficulties and misunderstandings encountered from lectures. Summaries are produced using a combination of phrase extraction, phrase clustering and phrase ranking based on student coverage, with the mobile interface highlighting the students’ own viewpoint in the summaries and noting the student coverage of each extracted phrase. A pilot deploy- ment yielded positive quantitative as well as quali- tative user feedback across two courses, suggesting the promise of CourseMIRROR for enhancing the instructor-student and student-student interactions. In the future, we will examine how the students’ re- sponses (e.g., response rate, length, quality) relate to student learning performance.
Show more

5 Read more

Evaluation of Multi-Touch Tabletop Collaborative Application Interfaces

Evaluation of Multi-Touch Tabletop Collaborative Application Interfaces

This dissertation is built on the field of Human-Computer Interaction (HCI), which is concerned with the study of the technology that supports collaborative activities from user’s perspective. Identifying design issues relevant to collaborative interfaces on selected applications by involving actual users to evaluate their interactions with these applications, and present their test outcome. This work will be concluded by proposing designing recommendations and identifying directions for future research on collaborative interaction techniques.

55 Read more

Bubble, bubble, toil, and trouble

Bubble, bubble, toil, and trouble

Since home prices are at least partial- ly driven by factors in a local market, virtually every study estimates prices at the state or metropolitan market level. Some studies find evidence that homes in selected local markets are overpriced (for example, Case and Shiller, 2003; and Himmelberg, Mayer, and Sinai, 2005), but others claim that there is not signifi- cant overpricing (for example, McCarthy and Peach, 2004). In the papers that found some overpricing, the areas where prices were estimated to be “too high” were often locations where the ability to build new houses was limited relative to demand. There is evi- dence that zoning restrictions are associated with high prices and that prices may behave differently in “superstar” cities than in other areas (Glaeser, Gyourko, and Saks, 2005; and Gyourko, Mayer, and Sinai, 2006). This brings up a related point that where homeowners are subject to more risk, prices may be more sensitive to shocks (Lamont and Stein, 1999; and Sinai and Souleles, 2003). Homeowners may be subject to more risk where homes are expensive (leading to homeowners having higher leverage) or where de- mand is inelastic, such as in superstar cities (McCarthy and Peach, 2004). Thus, what appears to be a bubble in some markets might just be a reflection of normal- ly high volatility in those markets.
Show more

20 Read more

Perceptible affordances and feedforward for
gestural interfaces: Assessing effectiveness of
gesture acquisition with unfamiliar interactions

Perceptible affordances and feedforward for gestural interfaces: Assessing effectiveness of gesture acquisition with unfamiliar interactions

their purpose. According to Sorensen (2009: 47), because a GUI does not provide a full sensorial experience, it is likened to a performative process rather than an exploratory one. Using a GUI “necessitates a certain skill set, steeped in memory and recall on the part of the user.” Therefore, ‘skill’ in these computational modes is like “remembering a recipe in order to use an application for a desired outcome”. Sorensen continues by explaining that personal computing requires in general 3-5 small tasks in order to access a larger application to perform a major task such as word processing: there are more objects of interest than meets the eye, e.g. sub-menus within menus and so on. Beaudoin-Lafon (2000: 447) explains, “In fact, WIMP interfaces…often use indirect manipulation of the objects of interest, through (direct) manipulation of interface elements such as menus and dialog boxes". However, in touch-based interactions, generally, user interaction and interface response occur over the same physical space, bridging the gap between input and output by displaying both on the same surface. This helps to integrate perception and action seamlessly into one environment, by enabling users to manipulate content directly, rather than through user interface controls, hence not requiring intermediates such as the mouse or keyboard. Ishii (1994) contends:
Show more

433 Read more

Transport of Solid Bodies Through Fluid Interfaces: From Flying Submarines to Cancer Spheroids.

Transport of Solid Bodies Through Fluid Interfaces: From Flying Submarines to Cancer Spheroids.

The existing literature considers three main subsets of unmanned aerial vehicles with some level of water functionality: seaplane UAVs, submarine-launched UAVs, and submersible UAVs [3]. Seaplane UAVs operate and function on the water surface and in the air. These vehicles are already being tested and fielded including research vehicles such as the ACAT [7] and the Flying Fish [8], [9] as well as commercial designs such as the RQ-15 Neptune [10], Sea Scout [11], and Gull series aircraft [12]. Submarine-launched UAVs are deployed from a submerged submarine via a waterproof housing or canister that encloses the vehicle until it reaches the surface. Once launched, these vehicles perform their flight missions and are then either retrieved from the surface or discarded. This subset includes the Sea Sentry, Blackwing, and XFC UAS [13]-[15]. Within the class of submersible UAVs, several commercially available multi-rotor UAVs have been designed with waterproof electronics [16]-[18], and are thus capable of surviving submergence. However, none of these vehicles are designed for true underwater operation including locomotion, maneuverability, and the ability to transition between domains.
Show more

115 Read more

Vortex interactions with topographic features in geophysical fluid dynamics

Vortex interactions with topographic features in geophysical fluid dynamics

These early studies revealed the first stage of the evolution of an intense vortex under the influence of /3. The studies of McWilliams and Flierl (1979) and Mied and Lindeman (1979) both showed th at an intense cyclone (resp. anticyclone) with an initially Gaussian vorticity distribution, follows a curved northwest (southwest) trajectory. The physical mechanism for this process is well understood. Consider the case of a cyclone. The sense of the circulation implies th a t fluid lying to the east of the vortex is advected north, and by virtue of potential vorticity conservation gains anticyclonic relative vorticity. To the west of the vortex, fluid advected south gains cyclonic relative vorticity. Thus initially, a dipolar secondary circulation is set up by the primary vortex sweeping fluid columns across the potential vorticity gradient. The sense of this dipole, the so-called /3-gyres2, is such as to initially induce a northward motion in the vortex. In the case of the weak vortex Rossby wave production dominates and energy is rapidly radiated away from the vortex, which in tu rn decays. In the case of an intense vortex the strong axisymmetric swirl of the vortex dominates the near field dynamics and the /3-gyres remain in the vicinity of the vortex. In turn the axisymmetric swirl of the vortex rotates the axis of the dipolar /3-gyres and consequently the vortex follows a curved northwest trajectory. The case of an anticyclone is analogous, but with the exception th at the motion is southwest.
Show more

238 Read more

Quantifying gaze and mouse interactions on spatial visual interfaces with a new movement analytics methodology

Quantifying gaze and mouse interactions on spatial visual interfaces with a new movement analytics methodology

The methodological question that we are addressing in this paper is how to quantify the con- nection in space and time between two moving ‘objects’, i.e. the positions of the gaze and the mouse pointer on the screen. Quantifying such connections is a long-standing problem in scientific disciplines that analyse movement data. While our approach has, as far as we are aware, not been applied in eye tracking, it is common in other disciplines, in particular in movement ecology, which investigates animal movement [40]. There, this connection is called the dynamic interaction (sometimes also relative motion between two objects, or association or correlation of two moving objects) and is defined as the level of inter-dependency between two moving individuals [41]. Analysing dynamic interaction allows ecologists to categorise various types of movement behaviour, thus learn more about the animals and their interactions with each other as well as with the environment. This analysis can be done either between individu- als, where patterns such as grouping, following, frequency of encounters or avoidance/attrac- tion are of interest [42,43]; or between co-located species, looking at predator/prey behaviours, avoidance or chasing [44,45].
Show more

36 Read more

Study of Hydrodynamics and Overall Gas Hold Up Validation in Bubble Column by Computational Fluid Dynamics

Study of Hydrodynamics and Overall Gas Hold Up Validation in Bubble Column by Computational Fluid Dynamics

The study of overall gas hold up has been carried out experimentally with the bed expansion. The superficial gas velocities used for the experiments are 6.369 m/s and 10.616 m/s. The experiment is carried out in a bubble column with inside diame- ters of 7 cm and a height of 100 cm. Gas from the gas cylinder is supplied through a distributor consisting of a perforated plate and glass beads. The perforated plate has a hole diameter of 1 mm and 0.5 mm. Computational Fluid Dynamic (CFD) using a Eulerian coupled with Population Balance model is developed to predict overall gas hold up and bubble size distribution. The effect of superficial gas velocity, per- forated plate diameter, gas properties, and initial liquid level on gas hold up were studied. The use of population balance can significantly improve the overall gas hold- up results compared to constant bubble diameter. It is found that several operating conditions affect the whole gas hold up, namely initial liquid level, superficial gas velocity, and differences in gas properties. While the influence of the difference in perforated plate diameter to overall gas holds up, results are small compared to other operating conditions.
Show more

10 Read more

PARTICLES- FLUID INTERACTIONS IN THE SETTLING VELOCITY OF NATURAL SANDS.

PARTICLES- FLUID INTERACTIONS IN THE SETTLING VELOCITY OF NATURAL SANDS.

from settling tanks don’t take into consideration the settling velocity variation according to the different particle sizes and more important the effect of other particles interacting between them and the fluid in this variation (Garcíaet al, 2000). In this research using experimental results, the goal is to establish the effect of the fluid velocity on the settling velocity of the particles and the effect other particles interacting with the fluid. The sand mixture was analyzed for different ranges of particle sizes using optical methods. A comparison is made with the experimental results and the different settling velocity formulas in the literature including Salinas and Garcia (2011) formula that takes into account the effect of the fluid velocity .
Show more

11 Read more

Supporting multi modal and multi medial user interfaces from an embedded environment

Supporting multi modal and multi medial user interfaces from an embedded environment

In the sequential one a system that supports multi-modal input is restricted by some form of progress script that determines at what point in a user interaction exchange a certain modality is allowed. Imagine a phone call to a technical support helpdesk (maybe that of Packard Bell) in which you are first required to enter the serial number of the troublesome device in question by means of the number keys on your phone. Next, in order to verify your current address which is read aloud by a text-to-speech voice syn- thesis application, you need to speak either the word ‘Yes’ or ‘No’. After that you can navigate though an Interactive Voice Response system by means of your number keys again, and finally go make some tea while you wait for an actual helpdesk representative to talk to you. One input modality interaction is clearly scheduled after the other, and no overlap or interaction between them takes place.
Show more

71 Read more

Show all 10000 documents...