scholarly journals Computational Methods for Moving and Deforming Objects in Extreme Waves

2019 ◽  
Author(s):  
Arthur E. P. Veldman ◽  
Henk Seubers ◽  
Matin Hosseini ◽  
Xing Chang ◽  
Peter R. Wellens ◽  
...  
Keyword(s):  
Well Being ◽  
Simulation Method ◽  
Engineering Problem ◽  
The Body ◽  
Green Water ◽  
Wave Forces ◽  
Offshore Platforms ◽  
Wave Loads ◽  
Floating Platform ◽  
Offshore Industry

Abstract Wave forces can form a serious threat to offshore platforms and ships. The damage produced by these forces of nature jeopardizes their operability as well as the well-being of their crews. Similar remarks apply to coastal defense systems. To develop the knowledge needed to safely design these constructions, in close cooperation with MARIN and the offshore industry the numerical simulation method ComFLOW is being developed. So far, its development was focussed on predicting wave loads (green water, slamming) on fixed structures, and for those applications the method is already being used successfully by the offshore industry. Often, the investigated object (ship, floating platform) is dynamically moving under the influence of these wave forces, and its hydrodynamic loading depends upon the position of the object with respect to the oncoming waves. Predicting the position (and deformation) of the body is an integral part of the (scientific and engineering) problem. The paper will give an overview of the algorithmic developments necessary to describe the above-mentioned physical phenomena. In particular attention will be paid to fluid-solid body and fluid-structure interaction and non-reflecting outflow boundary conditions. Several illustrations including validation, will demonstrate the prediction capabilities of the simulation method.

Effect of Seabed Slope on Offshore Pile Lateral Behaviour Under Wave Force

2010 ◽  
Author(s):  
Sathyanarayanan Dhandapani ◽  
Muthukkumaran Kasinathan
Keyword(s):  
Finite Element ◽  
Vertical Direction ◽  
Pile Group ◽  
Element Model ◽  
Wave Force ◽  
Wave Forces ◽  
Extreme Conditions ◽  
Offshore Platforms ◽  
Wave Loads ◽  
Offshore Structure

Fixed offshore platforms supported by pile foundations are required to resist dynamic lateral loading due to wave forces. The response of a jacket offshore tower is affected by the flexibility and nonlinear behavior of the supporting piles. In this study, a typical fixed offshore platform is chosen, and dynamic wave analysis is performed on it. Analysis has been performed for normal environmental conditions and extreme conditions. For the foundation, the deflections and reactions at regular intervals along the vertical direction from the seabed have been found out from the dynamic analysis, and the results have been compared for normal and extreme conditions. The aim of this study is to investigate the effects of the combined lateral and vertical loads on pile group foundation of a fixed offshore structure and the effects of seabed slope on the pile responses. To provide a more accurate and effective design for offshore pile foundation systems under axial structural loads and lateral wave loads, a finite element model which is modelled in FLAC3D is employed herein to determine the soil structure interaction under similar loading conditions. Three dimensional modelling and the analyses are done using FLAC3D — a finite element package.

CFD Calculations of the Vortex-Induced Motions of a Circular-Column Semi-Submersible

2016 ◽  
Author(s):  
Guilherme Feitosa Rosetti ◽  
Rodolfo Gonçalves ◽  
André Luís Condino Fujarra ◽  
Arjen Koop
Keyword(s):  
Practical Knowledge ◽  
Scale Effects ◽  
Engineering Problem ◽  
The Body ◽  
Design Stage ◽  
Total Force ◽  
Offshore Platforms ◽  
Circular Column ◽  
Wide Range ◽  
Floating Platforms

The vortex-induced motions (VIM) of offshore platforms stand as an intriguing and challenging engineering problem, drawing attention from industry, universities and research institutes. Field observations, model tests and calculations have extensively showed that the complex fluid-structure interaction can result in appreciable motions and increased fatigue of mooring and risers. It is thus a very relevant issue from the engineering standpoint. A large volume of experimental research has been carried out, mainly to verify designs and characterize the occurrence of VIM. Conversely, the numerical investigations applying CFD tools have shown to be a more flexible approach enabling better understanding of the physics at play due to the possibility of investigating the effects of different parameters upon the vortex induced motions of floating platforms. Moreover, the CFD calculations enable investigation of the full-scale behavior of the platforms under VIM, a very controversial issue presently. Bearing upon these issues, the VIM Joint Industry Project aims at increasing physical insight of this phenomenon by means of investigating the influence of geometric design variations, flow conditions and scale effects with the objective of improving practical knowledge that can be applied in the design stage of floating platforms. In this paper, we present some of the CFD studies, results and observations carried out within the JIP, regarding the VIM of a semi-submersible with circular columns in 0 and 45 degrees and over a wide range of reduced velocities. It is confirmed that the 0 degree incidence results in larger motions than the 45 degrees-incidence case, in contrast to the VIM behavior of a semi-submersible with square columns. The tests campaign carried out at the University of São Paulo for the same platform agree with these results. Within the lock-in range, the frequency synchronization of the lift forces on columns and pontoons cause large net transverse forces. Appreciable sway motions thus result. For larger reduced velocities, synchronization of the flow around the columns cease, but the forces on the pontoons then largely contribute to the total force. In this high-reduced velocity range, the phasing between total force and motion is such that energy transfer from the fluid to the body occurs, causing the amplification of the motions.

Nonlinear impulse of ocean waves on floating bodies

2012 ◽  
Vol 697 ◽  
pp. 316-335 ◽  
Author(s):  
Paul D. Sclavounos
Keyword(s):  
Time Derivative ◽  
Ocean Waves ◽  
The Body ◽  
Offshore Wind ◽  
Floating Body ◽  
Offshore Platforms ◽  
Wave Loads ◽  
Floating Bodies ◽  
Bernoulli’S Equation ◽  
Hydrostatic Force

AbstractA new formulation is presented of the nonlinear loads exerted on floating bodies by steep irregular surface waves. The forces and moments are expressed in terms of the time derivative of the fluid impulse which circumvents the time-consuming computation of the temporal and spatial derivatives in Bernoulli’s equation. The nonlinear hydrostatic force on a floating body is shown to point vertically upwards and the nonlinear Froude–Krylov force and moment are derived as the time derivative of an impulse that involves the time derivative of a simple integral of the ambient velocity potential over the time-dependent body wetted surface. The nonlinear radiation and diffraction forces and moments are expressed as time derivatives of two impulses, a body impulse and a free surface impulse that represents higher-order wave loads acting along the body waterline. Numerical results are presented illustrating the accuracy of the new force expressions. Applications discussed include the nonlinear seakeeping of ships and offshore platforms and the extreme wave loads and responses of offshore wind turbines.

Extreme Wave Impact on Offshore Platforms and Coastal Constructions

2011 ◽  
Author(s):  
Arthur E. P. Veldman ◽  
Roel Luppes ◽  
Tim Bunnik ◽  
Rene´ H. M. Huijsmans ◽  
Bulent Duz ◽  
...  
Keyword(s):  
Simulation Method ◽  
Coastal Protection ◽  
Wave Forces ◽  
Shear Stresses ◽  
Offshore Platforms ◽  
Extreme Wave ◽  
Wave Impact ◽  
Major Application ◽  
Cfd Method ◽  
Hydrodynamic Wave

Hydrodynamic wave loading on structures plays an important role in areas such as coastal protection, harbor design and offshore constructions (FPSO’s, mooring), and there is a need for its prediction up to a detailed level (max./min. pressures, duration of pressure peaks, shear stresses, etc.). In close cooperation with industry, long-year joint-industry projects are carried out to develop a numerical simulation method: the CFD method ComFLOW. The two major application areas are the prediction of extreme wave forces on offshore platforms and offloading vessels, and the prediction of impact forces on coastal protection structures. The paper will present a short overview of the method, some recent results and future plans.

Non-Linear Wave Forces Acting on a Body of Arbitrary Shape Slowly Oscillating in Waves

2005 ◽  
Author(s):  
Yasunori Nihei ◽  
Takeshi Kinoshita ◽  
Weiguang Bao
Keyword(s):  
Low Frequency ◽  
The Body ◽  
Coordinate Frame ◽  
Wave Forces ◽  
Linear Wave ◽  
Wave Loads ◽  
Low Frequency Oscillation ◽  
Wave Drift ◽  
Non Linear ◽  
Low Frequency Motion

In the present study, non-linear wave loads such as the wave drift force, wave drift damping and wave drift added mass, acting on a moored body is evaluated based on the potential theory. The body is oscillating at a low frequency under the non-linear excitation of waves. The problem of interaction between the low-frequency oscillation of the body and ambient wave fields is considered. A moving coordinate frame following the low frequency motion is adopted. Two small parameters, which measure the wave slope and the frequency of slow oscillations (compared with the wave frequency) respectively, are used in the perturbation analysis. So obtained boundary value problems for each order of potentials are solved by means of the hybrid method. The fluid domain is divided into two regions by an virtual circular cylinder surrounding the body. Different approaches, i.e. boundary element method and eigen-function expansion, are applied to these two regions. Calculated nonlinear wave loads are compared to the semi-analytical results to validate the present method.

Wave-in-Deck Forces on Offshore Platforms

2000 ◽  
Vol 123 (1) ◽  
pp. 10-21 ◽  
Author(s):  
R. G. Bea ◽  
R. Iversen ◽  
T. Xu
Keyword(s):  
Laboratory Test ◽  
Field Performance ◽  
Wave Force ◽  
Green Water ◽  
Extreme Condition ◽  
Wave Crest ◽  
Wave Forces ◽  
Offshore Platforms ◽  
Laboratory Test Results ◽  
Storm Wave

The extreme condition storm wave crest heights for many older platforms indicate that there would be “green water” in the lower decks. The API guidelines to determine wave forces acting on the decks of these platforms indicate that most platforms cannot survive such loadings. The decks must either be removed or the decks raised to clear the specified wave crests. A variety of laboratory tests have been performed to address this problem. Several approaches have been developed to compute the wave crest loadings and the responses of the platforms to the loadings. There have been many instances in which platforms have experienced significant wave loadings in their lower decks during hurricanes. Some of these platforms have survived and some have failed. This paper summarizes results from a study of laboratory test results and the performance of platforms in the Gulf of Mexico that have survived and failed during hurricane wave loadings in their decks. Modifications to the API deck wave force guidelines are discussed and validated with laboratory test data and platform field performance during hurricanes.

Integrating Focusing and Differentiation: A Therapeutic Path for Couples in Intimate Relationships

2018 ◽  
Vol 3 ◽  
Author(s):  
Evi Zohar
Keyword(s):  
Couples Therapy ◽  
Therapeutic Potential ◽  
Well Being ◽  
Point Of View ◽  
The Body ◽  
Self Awareness ◽  
Emotional Healing ◽  
Felt Sense ◽  
Inner World

Continuing the workshop I've given in the WPC Paris (2017), this article elaborates my discussion of the way I interlace Focusing with Differentiation Based Couples Therapy (Megged, 2017) under the systemic view, in order to facilitate processes of change and healing in working with intimate couples. This article presents the theory and rationale of integrating Differentiation (Bowen, 1978; Schnarch, 2009; Megged, 2017) and Focusing (Gendlin, 1981) approaches, and its therapeutic potential in couple's therapy. It is written from the point of view of a practicing professional in order to illustrate the experiential nature and dynamics of the suggested therapeutic path. Differentiation is a key to mutuality. It offers a solution to the central struggle of any long term intimate relationship: balancing two basic life forces - the drive for individuality and the drive for togetherness (Schnarch, 2009). Focusing is a body-oriented process of self-awareness and emotional healing, in which one learns to pay attention to the body and the ‘Felt Sense’, in order to unfold the implicit, keep it in motion at the precise pace it needs for carrying the next step forward (Gendlin, 1996). Combining Focusing and Differentiation perspectives can cultivate the kind of relationship where a conflict can be constructively and successfully held in the inner world of each partner, while taking into consideration the others' well-being. This creates the possibility for two people to build a mutual emotional field, open to changes, permeable and resilient.

Psychosocial Consequences of Body Weight and Obesity

2018 ◽  
pp. 274-286
Author(s):  
Deborah Carr ◽  
Vera K. Tsenkova
Keyword(s):  
Body Weight ◽  
Interpersonal Relationships ◽  
Large Scale ◽  
Well Being ◽  
The United States ◽  
Overweight And Obesity ◽  
The Body ◽  
Integrative Health ◽  
Psychosocial Consequences ◽  
Adults And Children

The body weight of U.S. adults and children has risen markedly over the past three decades. The physical health consequences of obesity are widely documented, and emerging research from the Midlife in the United States study and other large-scale surveys reveals the harmful impact of obesity on adults’ psychosocial and interpersonal well-being. This chapter synthesizes recent research on the psychosocial implications of body weight, with attention to explanatory mechanisms and subgroup differences in these patterns. A brief statistical portrait of body weight is provided, documenting rates and correlates of obesity, with a focus on race, gender, and socioeconomic status disparities. The consequences of body weight for three main outcomes are described: institutional and everyday discrimination, interpersonal relationships, and psychological well-being. The chapter concludes with a discussion of the ways that recent integrative health research on the psychosocial consequences of overweight and obesity inform our understanding of population health.

scholarly journals Transition from Emotional to Rational Advertising for Food Products on the Romanian Market

2017 ◽  
Vol 50 (1) ◽  
pp. 101-108
Author(s):  
A.F. Jităreanu ◽  
Elena Leonte ◽  
A. Chiran ◽  
Benedicta Drobotă
Keyword(s):  
Urban Areas ◽  
Eating Habits ◽  
Well Being ◽  
Point Of View ◽  
The Body ◽  
Positive Effects ◽  
New Methods ◽  
Brand Advertising ◽  
Tangible Evidence ◽  
Health And Well Being

Abstract Advertising helps to establish a set of assumptions that the consumer will bring to all other aspects of their engagement with a given brand. Advertising provides tangible evidence of the financial credibility and competitive presence of an organization. Persuasion is becoming more important in advertising. In marketing, persuasive advertising acts to establish wants/motivations and beliefs/attitudes by helping to formulate a conception of the brand as being one which people like those in the target audience would or should prefer. Considering the changes in lifestyle and eating habits of a significant part of the population in urban areas in Romania, the paper aims to analyse how brands manage to differentiate themselves from competitors, to reposition themselves on the market and influence consumers, meeting their increasingly varied needs. Food brands on the Romanian market are trying, lately, to identify new methods of differentiation and new benefits for their buyers. Given that more and more consumers are becoming increasingly concerned about what they eat and the products’ health effects, brands struggle to highlight the fact that their products offer real benefits for the body. The advertisements have become more diversified and underline the positive effects, from the health and well - being point of view, that those foods offer (no additives and preservatives, use of natural ingredients, various vitamins and minerals or the fact that they are dietary). Advertising messages’ diversification is obvious on the Romanian market, in the context of an increasing concern of the population for the growing level of information of some major consumer segments.

scholarly journals Medical Students’ Experience of Mindfulness Training in the UK: Well-Being, Coping Reserve, and Professional Development

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Alice Malpass ◽  
Kate Binnie ◽  
Lauren Robson
Keyword(s):  
Medical Education ◽  
Mental Health Problems ◽  
Qualitative Interviews ◽  
General Medical Council ◽  
Well Being ◽  
Mindfulness Training ◽  
The Body ◽  
Free Text ◽  
Medical Council ◽  
The Uk

Medical school can be a stressful experience for students, resulting in stress-related mental health problems. Policy recommendations from the General Medical Council (GMC), the body responsible for improving medical education in the UK, recommend the use of mindfulness training to increase well-being and resilience to stress. Students participating in an eight-week mindfulness training between Autumn 2011 and Spring 2015 were invited to complete a free text survey at the end of their mindfulness course. In addition, six qualitative interviews were conducted lasting between 60 and 90 minutes. Interviews used a topic guide and were recorded and transcribed verbatim. We used the framework approach to analyse the data. Students reported a new relationship to their thoughts and feelings which gave a greater sense of control and resiliency, an ability to manage their workload better, and more acceptance of their limitations as learners. The small group context was important. Students described improved empathy and communication skills through building inner awareness of thoughts and feelings, noticing judgments, and developing attentive observation. The findings show how resiliency and coping reserve can be developed within medical education and the role of mindfulness in this process. We present a conceptual model of a learnt cycle of specific vulnerability and describe how MBCT intercepts at various junctures in this self-reinforcing cycle through the development of new coping strategies that embrace an “allowed vulnerability.”

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