Freestream Nuclei and Traveling-Bubble Cavitation

1992 ◽  
Vol 114 (4) ◽  
pp. 672-679 ◽  
Author(s):  
R. S. Meyer ◽  
M. L. Billet ◽  
J. W. Holl
Keyword(s):  
Bubble Diameter ◽  
Pressure Coefficient ◽  
Critical Diameter ◽  
Computer Code ◽  
The Body ◽  
Water Tunnel ◽  
Cavitation Inception ◽  
Bubble Cavitation ◽  
Definition Of ◽  
Critical Bubble

Traveling-bubble cavitation inception tests were conducted in a 30.48 cm water tunnel with a Schiebe headform. A computer code was developed to statistically model cavitation inception on a Schiebe headform, consisting of a numerical solution to the Rayleigh-Plesset equation coupled to a set of trajectory equations. Using this code, trajectories and growths were computed for bubbles of varying initial sizes. An initial off-body distance was specified and the bubble was free to follow an off-body trajectory. A Monte Carlo cavitation simulation was performed in which a variety of random processes were modeled. Three different nuclei distributions were specified including one similar to that measured in the water tunnel experiment. The results compared favorably to the experiment. Cavitation inception was shown to be sensitive to nuclei distribution. Off-body effect was also found to be a significant factor in determining whether or not a bubble would cavitate. The effect of off-body trajectories on the critical bubble diameter was examined. The traditional definition of critical diameter based on the minimum pressure coefficient of the body or the measurement of liquid tension was found to be inadequate in defining cavitation inception.

Cavitation Inception Behind a Jet-Propelled Body

2007 ◽  
Author(s):  
William Hambleton ◽  
Eduard Amromin ◽  
Roger E. A. Arndt ◽  
Svetlana Kovinskaya
Keyword(s):  
Velocity Ratio ◽  
The Body ◽  
Force Balance ◽  
Water Tunnel ◽  
Minimum Diameter ◽  
Cavitation Inception ◽  
Initial Comparison ◽  
Jet Velocity ◽  
Good Agreement

Cavitation inception behind an axissymmetric body driven by a waterjet has been studied experimentally and numerically. Water tunnel tests have been performed with the body mounted on a force balance. The transom of the body contained a nozzle located along the centerline. Tests were carried out for various water tunnel speeds such that jet velocity ratio, VJ/U, could be varied in the range 0 to 2. Distinctly different cavitation patterns were observed at zero jet velocity (when cavitation appeared in spiral vortices in such flows) and at a various jet velocity ratios (when cavitation appeared between counter-rotating vortices around the jet in such flows). Cavitation inception/disappearance has been determined visually. The body drag was also measured. An analytical method for determination of cavitation inception index has been developed on the basis of a viscous-inviscid interaction concept, with employment of special semiempirical approximations for vortices and consideration of surface tension. These approximations have been preliminarily validated for nozzle jet cavitation (for nozzle discharge in co-flow). It was assumed that visualization allows detection of cavities (bubbles) of 0.4mm-0.5mm diameter or larger. The cavitation inception index is defined as the cavitation index for cavities of such minimum diameter when these cavities are located between counter-rotating vortices. The initial comparison of predicted and measured values of the cavitation inception index shows good agreement.

Cavitation Inception Tests on Axisymmetric Headforms

1981 ◽  
Vol 103 (2) ◽  
pp. 268-272 ◽  
Author(s):  
Sen-sen Pan ◽  
Zhan-ming Yang ◽  
Pei-shuen Hsu
Keyword(s):  
Scientific Research ◽  
Flow Regimes ◽  
Flow Patterns ◽  
The Body ◽  
Research Center ◽  
Water Tunnel ◽  
Cavitation Inception ◽  
Air Content ◽  
Flow Past ◽  
Wall Flow

Six axisymmetric headforms were tested in the 350-mm dia water tunnel at China Ship Scientific Research Center (CSSRC) for observation and measurement of cavitation inception. Among them, three of the flow patterns were displayed and analyzed by holography. Results of the tests show that cavitation inception on the headforms was closely related to the structure of the near-wall flow past the body with different flow regimes corresponding to different features of cavitation inception. By carefully fitting a trip wire of suitable height on a hemispherical headform, it was observed that under conditions of low air content, this artificial means of boundary transition may bring about a significant reduction in cavitation inception number.

Viscous and Nuclei Effects on Hydrodynamic Loadings and Cavitation of a NACA 66 (MOD) Foil Section

1989 ◽  
Vol 111 (3) ◽  
pp. 306-316 ◽  
Author(s):  
Y. T. Shen ◽  
P. E. Dimotakis
Keyword(s):  
Pressure Distribution ◽  
Pressure Coefficient ◽  
Leading Edge ◽  
Full Scale ◽  
Pressure Loading ◽  
Foil Surface ◽  
Negative Minimum ◽  
Cavitation Inception ◽  
Minimum Pressure ◽  
Bubble Cavitation

A series of experiments has been conducted on a two-dimensional NACA 66 (MOD) foil to examine the effects of viscosity and nuclei on cavitation inception. In this paper the main discussions center on two foil angles having different types of pressure loadings to represent a propeller blade section operating at design and off-design conditions. At one degree design angle of attack the foil experiences a rooftop-type gradually varying pressure distribution. At three degrees off-design angle of attack the foil experiences a sharp suction pressure peak near the leading edge. Cebeci’s viscid/inviscid interactive code is used to compute the viscous scale effects on the development of the boundary layer, lift, drag and pressure distribution on the foil. Chahine’s multibubble interaction code is used to compute the effect of nuclei, test speeds, foil size and foil surface on traveling bubble cavitation. Both computer codes are found to agree satisfactorily with the experimental measurements reported here. Two assumptions commonly used to predict full scale surface cavitation from model tests are examined experimentally and theoretically. The first assumption states that cavitation inception occurs when the static pressure reaches the vapor pressure. On the contrary, the experiments showed that the water flowing over the foil surface sustained significant amounts of tension during inception of midchord bubble cavitation as well as leading edge sheet cavitation. The second assumption states that there is no scale effect on the values of negative minimum pressure coefficient. In the case of a rooftop-type pressure loading, the second assumption is supported by the pressure numerical calculations. However, in the case of a pressure loading with a strong suction peak near the leading edge the value of negative minimum pressure coefficient is as much as 12 to 15 percent lower on a model than at full scale.

Derrida on Pornography: Putting (It) Up for Sale

Derrida Today ◽  
2013 ◽  
Vol 6 (1) ◽  
pp. 97-114 ◽  
Author(s):  
Christopher Morris
Keyword(s):  
Cultural Studies ◽  
English Translation ◽  
The Body ◽  
The Past ◽  
French Original ◽  
Definition Of ◽  
Critical Discourses ◽  
Academic Debate

Over the past thirty years, academic debate over pornography in the discourses of feminism and cultural studies has foundered on questions of the performative and of the word's definition. In the polylogue of Droit de regards, pornography is defined as la mise en vente that is taking place in the act of exegesis in progress. (Wills's idiomatic English translation includes an ‘it’ that is absent in the French original). The definition in Droit de regards alludes to the word's etymology (writing by or about prostitutes) but leaves the referent of the ‘sale’ suspended. Pornography as la mise en vente boldly restates the necessary iterability of the sign and anticipates two of Derrida's late arguments: that there is no ‘the’ body and that performatives may be powerless. Deriving a definition of pornography from a truncated etymology exemplifies the prosthesis of origin and challenges other critical discourses to explain how pornography can be understood as anything more than ‘putting (it) up for sale’.

scholarly journals Zur exakten Behandlung von kollektiven Rotationen Teil A: Theorie / On the Exact Treatment of Collective Rotations Part A: Theory

1973 ◽  
Vol 28 (2) ◽  
pp. 206-215
Author(s):  
Hanns Ruder
Keyword(s):  
Coordinate System ◽  
Perturbation Expansion ◽  
Rotational Energy ◽  
The Body ◽  
System A ◽  
N Body Problem ◽  
Definition Of ◽  
Fixed System ◽  
Body Fixed Coordinate System ◽  
Groundstate Energy

Basic in the treatment of collective rotations is the definition of a body-fixed coordinate system. A kinematical method is derived to obtain the Hamiltonian of a n-body problem for a given definition of the body-fixed system. From this exact Hamiltonian, a consequent perturbation expansion in terms of the total angular momentum leads to two exact expressions: one for the collective rotational energy which has to be added to the groundstate energy in this order of perturbation and a second one for the effective inertia tensor in the groundstate. The discussion of these results leads to two criteria how to define the best body-fixed coordinate system, namely a differential equation and a variational principle. The equivalence of both is shown.

scholarly journals Spiritual nursing care: A concept analysis

Curationis ◽  
2012 ◽  
Vol 35 (1) ◽  
Author(s):  
Lydia V. Monareng
Keyword(s):  
Nursing Care ◽  
Concept Analysis ◽  
Operational Definition ◽  
The Body ◽  
Empirical Literature ◽  
Spiritual Needs ◽  
Optimal Care ◽  
Health Crisis ◽  
Group Interviews ◽  
Definition Of

Although the concept ‘spiritual nursing care’ has its roots in the history of the nursing profession, many nurses in practice have difficulty integrating the concept into practice. There is an ongoing debate in the empirical literature about its definition, clarity and application in nursing practice. The study aimed to develop an operational definition of the concept and its application in clinical practice. A qualitative study was conducted to explore and describe how professional nurses render spiritual nursing care. A purposive sampling method was used to recruit the sample. Individual and focus group interviews were audio-taped and transcribed verbatim. Trustworthiness was ensured through strategies of truth value, applicability, consistency and neutrality. Data were analysed using the NUD*IST power version 4 software, constant comparison, open, axial and selective coding. Tech’s eight steps of analysis were also used, which led to the emergence of themes, categories and sub-categories. Concept analysis was conducted through a comprehensive literature review and as a result ‘caring presence’ was identified as the core variable from which all the other characteristics of spiritual nursing care arise. An operational definition of spiritual nursing care based on the findings was that humane care is demonstrated by showing caring presence, respect and concern for meeting the needs not only of the body and mind of patients, but also their spiritual needs of hope and meaning in the midst of health crisis, which demand equal attention for optimal care from both religious and nonreligious nurses.

scholarly journals A global framework for a systemic view of brain modeling

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Frederic Alexandre
Keyword(s):  
Instrumental Conditioning ◽  
The Body ◽  
Posterior Cortex ◽  
Reciprocal Relationships ◽  
Brain Modeling ◽  
Brain Theory ◽  
Habitual Behavior ◽  
Definition Of ◽  
The Brain ◽  
Specific Contribution

AbstractThe brain is a complex system, due to the heterogeneity of its structure, the diversity of the functions in which it participates and to its reciprocal relationships with the body and the environment. A systemic description of the brain is presented here, as a contribution to developing a brain theory and as a general framework where specific models in computational neuroscience can be integrated and associated with global information flows and cognitive functions. In an enactive view, this framework integrates the fundamental organization of the brain in sensorimotor loops with the internal and the external worlds, answering four fundamental questions (what, why, where and how). Our survival-oriented definition of behavior gives a prominent role to pavlovian and instrumental conditioning, augmented during phylogeny by the specific contribution of other kinds of learning, related to semantic memory in the posterior cortex, episodic memory in the hippocampus and working memory in the frontal cortex. This framework highlights that responses can be prepared in different ways, from pavlovian reflexes and habitual behavior to deliberations for goal-directed planning and reasoning, and explains that these different kinds of responses coexist, collaborate and compete for the control of behavior. It also lays emphasis on the fact that cognition can be described as a dynamical system of interacting memories, some acting to provide information to others, to replace them when they are not efficient enough, or to help for their improvement. Describing the brain as an architecture of learning systems has also strong implications in Machine Learning. Our biologically informed view of pavlovian and instrumental conditioning can be very precious to revisit classical Reinforcement Learning and provide a basis to ensure really autonomous learning.

The Meaning of Pain and the Pain of Meaning: A Bio-Hermeneutical Inquiry

2021 ◽  
Vol 90 ◽  
pp. 215-234
Author(s):  
Teodora Manea
Keyword(s):  
The Body ◽  
Main Interest ◽  
Main Approach ◽  
Memento Mori ◽  
Finding Meaning ◽  
Pace Of Life ◽  
Before And After ◽  
Definition Of

AbstractMy main interest here is to look at pain as a sign of the body that something is wrong. I will argue that there is a meaning of pain before and after an illness is diagnosed. An illness contains its own semantic paradigm, but the pain before the diagnosis affects the pace of life, not only by limiting our interactions, but also as a struggle with its meaning and a reminder of mortality.My main approach is what I call bio-hermeneutics, an extension of medical hermeneutics branching out from the Continental hermeneutical tradition. As such, I will explore the connection between pain and language, temporality, dialectics, and ontology. Given the centrality of language in constructing the meaning of pain, my analysis is informed by the semantics (looking at pain metaphors), syntax (pain as incoherence), and pragmatics (pain as companion) of expressing pain.The last section explores the meaning of pain in connection with death, as memento mori. Revisiting an old definition of philosophy as melete thanatou, or ‘rehearsal of death’, I will reflect on the difficulty of finding meaning not only for pain, but also for death as cessation of all existential possibilities.

Water-tunnel studies of heat balance in swimming mako sharks

2001 ◽  
Vol 204 (23) ◽  
pp. 4043-4054 ◽  
Author(s):  
Diego Bernal ◽  
Chugey Sepulveda ◽  
Jeffrey B. Graham
Keyword(s):  
Heat Transfer ◽  
Heat Balance ◽  
Underlying Mechanism ◽  
The Body ◽  
Morphological Properties ◽  
Water Tunnel ◽  
Vascular Networks ◽  
Red Muscle ◽  
Counter Current ◽  
New Evidence

SUMMARY The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5–13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (Ta) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in Ta nor the direction of change in Ta had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3–3°C above Ta) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from Ta recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

Bodily Dasein and Chinese Script Components

2017 ◽  
Vol 2017 (2) ◽  
Author(s):  
Kwan Tze-wan
Keyword(s):  
Human Body ◽  
The Body ◽  
Chinese Script ◽  
Chinese Characters ◽  
Body Parts ◽  
Constitutive Principle ◽  
New Perspective ◽  
Social Environmental ◽  
The One ◽  
Definition Of

AbstractIn the Shuowen, one of the earliest comprehensive character dictionaries of ancient China, when discussing where the Chinese characters derive their structural components, Xu Shen proposed the dual constitutive principle of “adopting proximally from the human body, and distally from things around.” This dual emphasis of “body” and “things around” corresponds largely to the phenomenological issues of body or corporeality on the one hand, and lifeworld on the other. If we borrow Heidegger’s definition of Dasein as Being-in-the world, we can easily arrive at a reformulation of Xu Shen’s constitutive principle of the Chinese script as one that concerns “bodily Dasein.” By looking into various examples of script tokens we can further elaborate on how the Chinese make use not only of the body in general but various body parts, and how they differentiate their life world into material nature, living things, and a multifaceted world of equipment in forming a core basis of Chinese characters/components, upon which further symbolic manipulation such as “indication”, “phonetic borrowing”, semantic combination, and “annotative derivation”, etc. can be based. Finally, examples will be cited to show how in the Chinese scripts the human body (and its parts) might interact with other’s bodies (and their parts) or with “things around” (whether nature, living creatures, or artifacts) in various ways to cover the social, environmental, ritual, technical, economical, and even intellectual aspects of human experience. Bodily Dasein, so to speak, provides us with a new perspective of understanding and appreciating the entire scope of the Chinese script.

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