scholarly journals Strong fluid–solid interactions with segregated CFD solvers

2019 ◽  
Vol 29 (7) ◽  
pp. 2237-2252 ◽  
Author(s):  
Mathieu Olivier ◽  
Olivier Paré-Lambert

Purpose This paper aims to present a fluid-structure coupling partitioned scheme involving rigid bodies supported by spring-damper systems. This scheme can be used with already existing fluid flow solvers without the need to modify them. Design/methodology/approach The scheme is based on a modified Broyden method. It solves the equations of solid body motion in which the external forces coming from the flow are provided by a segregated flow solver used as a black box. The whole scheme is implicit. Findings The proposed partitioned method is stable even in the ultimate case of very strong fluid–solid interactions involving a massless cylinder oscillating with no structural damping. The overhead associated with the coupling scheme represents an execution time increase by a factor of about 2 to 5, depending on the context. The scheme also has the advantage of being able to incorporate turbulence modeling directly through the flow solver. It has been tested successfully with URANS simulations without wall law, thus involving thin high aspect-ratio cells near the wall. Originality/value Such problems are known to be very difficult to solve and previous studies usually rely on monolithic approaches. To the authors' knowledge, this is the first time a partitioned scheme is used to solve fluid–solid interactions involving massless components.

2017 ◽  
Vol 11 (4) ◽  
pp. 523-534
Author(s):  
Amir M. Sharif ◽  
Zahir Irani

Purpose This paper aims to explain the uncertainties associated with food security and, in doing so, classifies them within the context of volatility, uncertainty, complexity and ambiguity (VUCA). In using this lens to frame the challenges of food security, the viewpoint proffers the need to be even more sensitive to heightened levels of uncertainty and highlights the need of governments to be prepared to meet a wider variety of external forces, risks, opportunities and threats to mitigate food insecurity. Design/methodology/approach This research constructs a novel morphology of food security and food waste policy futures based upon a range of scenario types based on contextual narratives relating to constraint, collapse, growth and transformation. In doing so, offering a representation that suggests order, complexity and chaos occur across a range of four domains of interaction: known (repeatable cause and effect); knowable (cause and effect separated over time); complex (cause and effect are unique and non-repeatable); and chaos (no cause and effect relationship perceivable). This orientation is represented in the form of a novel morphology that can be used to support decision-making and policymaking/consideration. Findings The authors have presented and identified a combination of a structured and unstructured methods to develop and hence classify a range of food security scenarios. Using the VUCA worldview and classification, the authors subsequently identify seven underlying and seven United Nations (UN) Sustainable Development Goals (SDG)-derived factors, which when combined with the Institute for the Future (IFTF) four food security scenarios in a pairwise manner led to the generation of a further 16 subsequent VUCA-inspired scenarios composed within a morphological grid. These were subsequently reclassified against three sets of stakeholders and then finally mapped to the Cynefin framework as a set of ten scenarios to show the potential of making greater sense of the VUCA nature of food security. Practical implications The paper proposes a novel conceptual approach to framing and understanding the wider holistic aspects of explaining and providing foresight to the complexities of food security. Hence, this paper provides policymakers with two contrasting, yet complementary, food security scenario planning techniques (VUCA and Cynefin), which envelope 16 narrative food security scenarios which can be used with stakeholders and advocacy groups in facilitating discussion about complex, messy and “wicked” interlinkages within the food security domain. Originality/value This is the first time in the extant literature that a combination of structured and unstructured, problem-based versus mess-based, contrasting perspectives have been brought together and developed, with the intention of creating a normative family or portfolio of narrative-driven food security scenarios. The authors present and extend four existing scenarios from the extant food security literature, and subsequently, through interpreting these scenarios via a dual and combined lens (notably using UN SDG and VUCA elements), a grid of alternative food security scenarios is produced. By then using applying the Cynefin complexity framework to these new configurations, a thematic categorisation of alternative futures is presented, which may aid policy and decision-makers when considering this topic.


2014 ◽  
Vol 24 (7) ◽  
pp. 1537-1544 ◽  
Author(s):  
Rainald Löhner ◽  
Joseph D. Baum

Purpose – Prompted by the empirical evidence that achievable flow solver speeds for large problems are limited by what appears to be a time of the order of O(0.1) sec/timestep regardless of the number of cores used, the purpose of this paper is to identify why this phenomenon occurs. Design/methodology/approach – A series of timing studies, as well as in-depth analysis of memory and inter-processors transfer requirements were carried out for a typical field solver. The results were analyzed and compared to the expected performance. Findings – The analysis shows that at present flow speeds per core are already limited by the achievable transfer rate to RAM. For smaller domains/larger number of processors, the limiting speed of CFD solvers is given by the MPI communication network. Research limitations/implications – This implies that at present, there is a “limiting useful size” for domains, and that there is a lower limit for the time it takes to update a flowfield. Practical implications – For practical calculations this implies that the time required for running large-scale problems will not decrease markedly once these applications migrate to machines with hundreds of thousands of cores. Originality/value – This is the first time such a finding has been reported in this context.


2019 ◽  
Vol 36 (2) ◽  
pp. 21-22
Author(s):  
Ray Harper

Purpose The purpose of this paper is to summarise a number of presentations at Day 1 of the Internet Librarian International conference, London, UK (16 October 2018). This was the 20th conference in the series, and the three key themes included were the next-gen library and librarian; understanding users, usage and user experience; and inclusion and inspiration: libraries making a difference. Design/methodology/approach This paper reports from the viewpoint of a first-time attendee of the conference. This summarises the main issues raised by each presentation and draws out the key learning points for practical situations. Findings The conference covered a variety of practical ways in which libraries can use technology to support users and make decisions about services. These include developing interactive physical spaces which include augmented reality; introducing “chat-bots” to support users; using new techniques to analyse data; and piloting new ways to engage users (such as coding clubs). A key theme was how we use and harness data in a way that is ethical, effective and relevant to library services. Originality/value This conference focussed on practical examples of how library and information services across sectors and countries are innovating in a period of huge change. The conference gave delegates numerous useful ideas and examples of best practice and demonstrated the strength of the profession in adapting to new technologies and developments.


2019 ◽  
Vol 37 (1) ◽  
pp. 134-142
Author(s):  
Alberto Bueno-Guerrero

Purpose This paper aims to study the conditions for the hedging portfolio of any contingent claim on bonds to have no bank account part. Design/methodology/approach Hedging and Malliavin calculus techniques recently developed under a stochastic string framework are applied. Findings A necessary and sufficient condition for the hedging portfolio to have no bank account part is found. This condition is applied to a barrier option, and an example of a contingent claim whose hedging portfolio has a bank account part different from zero is provided. Originality/value To the best of the authors’ knowledge, this is the first time that this issue has been addressed in the literature.


2020 ◽  
Vol 12 (1) ◽  
pp. 307-323
Author(s):  
Qizhong Wang ◽  
Zhongquan Li ◽  
Yuan Yin ◽  
Shuang Yang ◽  
Wei Long ◽  
...  

AbstractThe Western Sichuan Plateau (WSP), located in the eastern margin of the Qinghai–Tibet Plateau, is the most strongly deformed region of the continental crust in China. Frequent tectonic movements shape the unique topography and landform of the WSP and have also produced abundant geological heritage resources. Based on the existing geological heritage survey data in Sichuan Province, the nearest index analysis method of employing a regional spatial point model was used to reveal the distribution rules and the genetic mechanism of typical geological relics in the WSP for the first time. Results indicate that the formation and distribution of geological relics in the WSP are generally controlled by tectonic movement and supplemented by the comprehensive action of external forces such as flowing water. Their distribution shows a condensed spatial distribution pattern and extends along the strike of a fault zone and river strike strip. Finally, based on the characteristics of geological relics in the WSP, some suggestions on the protection and development of regional geological relics were put forward.


Author(s):  
Robert Douglas Hinshelwood ◽  
Luca Mingarelli ◽  
Simona Masnata

Purpose Many people in severe mentally disturbed states do not use language or other symbolic media well or coherently. Therefore, the non-verbal medium needs to be understood by workers with such people. The “Learning from Action” experiential workshop was developed in order to provide an opportunity to learn about hidden messages in the relationships and roles occurring in activities. In August 2017, a workshop was run for the first time in Japan. The purpose of this paper is to report the experience and dynamics observed by the three consultants, who are here the authors of this paper. Design/methodology/approach After the workshop all the staff and members, including interpreters, were invited to give feedback. Findings Analysis of the feedback data showed certain important dynamics, concerning especially dependence, cultural defences and the defensive role of activity in a multicultural context. Research limitations/implications This is an initial experience to be followed up by later feedback and further workshops. Practical implications Workers awareness of non-verbal communication within the roles of work activities is a training possibility. It faces various resistances including the mental health assumptions of meaninglessness of any communication outside the verbal. Originality/value This is a method of training not widely used even in European countries, and is the first in a country in the far east.


2019 ◽  
Vol 25 (2) ◽  
pp. 257-284
Author(s):  
Armen E. Petrosyan

Purpose The paper aims to present a systematic conceptual analysis of the problem of organizational goal and to reduce the insights into it provided by the main conceptions taken in their development from one to another, to break out of the ruling paradigm and outline a new solution. Design/methodology/approach The study has been carried out from the historical and critical perspective. Findings The paper discovers the logic of the evolution the approaches to organizational goals have undergone and portrays it in a matrix form in the heart of which is the “zigzag effect”: each posterior stage returns to the essential elements rejected by those preceding it, and the last stage, being diametrically opposite to the first, is, at that, as well as the latter, akin to the intermediate stages. The opportunities afforded by the current paradigm have been exhausted and it seems to run to an impasse. Instead, the author suggests a new frame of orientation: organizational goals are closely interknit with personal, but not reducible to them and bear fundamentally transpersonal character, while the mechanism of involving the preferences of individuals and groups in goal-setting is based on the self-contained interests of the organization they pertain to. Research limitations/implications The findings, conclusions and generalizations obtained can serve for a necessary ground to researchers getting deeper into the essence of what bonds organizational life and activity. Practical implications The material empowers practitioners to comprehend the difficulties of framing cohesive goal and find efficient ways to overcome them. It is of value also to the teachers seeking to present a more exact and elaborate view of teleological foundations of management and organization theory. Originality/value Both the conceptual analysis of the evolution of the approaches to organizational goals and the author’s exposition of its logic and vision of their nature are provided for the first time.


2018 ◽  
Vol 60 (2) ◽  
pp. 681-700 ◽  
Author(s):  
Androniki Katarachia ◽  
Electra Pitoska ◽  
Grigoris Giannarakis ◽  
Elpida Poutoglidou

Purpose Based on agency theory, the purpose of this paper is to investigate the determinants on the dissemination level of corporate governance disclosure (CGD). Design/methodology/approach The sample of the study incorporates listed companies in Nifty 500 Index for the period 2009-2014. The Governance Disclosure Score calculated by Bloomberg is used as a proxy for the dissemination level of corporate governance information. In total, eight explanatory variables are uses, namely, board’s size, number of board meetings, CEO duality, presence of women on the board, company’s size, financial performance, Tobin’s Q ratio and financial leverage. Findings The results of study suggest a need for improvement in CGDs by Indian companies, as they fail to comply the majority of the proposed disclosure items. Furthermore, it is revealed that the number of board director, the value of company, the financial leverage and the presence of women affect negatively the dissemination level of corporate governance information. While, the size of company is the only determinant that positively affects the extent of CGD. Practical implications The results are valuable because they reveal the attributes that determines which companies needs less or extra monitoring by shareholders and investors regarding the applied corporate governance practices. In addition, the study can be valuable to policy makers responsible for the regulation of company’s accountability in relation to corporate governance practices. Originality/value The study extents previous studies by incorporating for the first time Bloomberg’s rating approach regarding the dissemination level of CGD in Indian context.


2014 ◽  
Vol 69 (2) ◽  
pp. 137-157 ◽  
Author(s):  
Shogo Mlozi

Purpose – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Design/methodology/approach – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Findings – The findings for overall model differed from the moderating factors of high risk, low risk, first-time visit and repeat visit. Also, the results are interesting when satisfaction is tested as a mediator. Practical implications – Practitioners could consider the fact that repeat visits may change tourists’ perceptions toward destination and may even increase their inclination to take on risks. This may impact innovation of consumer products in tourism. Also, policy makers could benefit on how loyalty programs can be developed to increase performance. Originality/value – The study offers specific strategic recommendations toward different groups of tourists (i.e. first-time, repeat visitors, risk averse, risk seeking) and proposes logic for setting up a loyalty program as a long-term strategy for success.


2018 ◽  
Vol 120 (8) ◽  
pp. 1915-1928
Author(s):  
Judith Müller-Maatsch ◽  
Johannes Jasny ◽  
Katharina Henn ◽  
Claudia Gras ◽  
Reinhold Carle

Purpose The purpose of this paper is to provide insight into the consumers’ perception of natural and artificial food colourants. Furthermore, attitudes towards the application of carmine, being technically important and ubiquitously used to impart red shades, are assessed and analysed. Originating from insects, carmine is considered as natural but may arouse disgust. Design/methodology/approach In total, 625 individuals were surveyed using an online, self-administered questionnaire to represent a broad cross-section of the German population. Findings Independent of their origin, the application of colourants was rejected by 57.0 per cent of the interviewees. In total, 31.8 per cent of the participants stated a neutral attitude, while only 11.2 per cent expressed a positive notion. Most respondents preferred colourants from natural sources to artificial ones. While consumers perceive natural food colourants composed of genuine plant pigments positively, 61.6 per cent of respondents disliked the application of animal-derived colourants, 24.8 per cent of them did neither reject nor like it, and only 13.6 per cent of the interviewees stated a positive attitude towards them. The findings of this paper further indicate consumers’ preference for colourants to be either artificial or plant-derived rather than carmine. Food colourants are being rejected, possibly due to misleading information and confusing labelling. Consequently, information about carmine, including its origin and production, did not increase the aversion to products that are dyed with it, but increased their acceptance. Originality/value This study outlines consumer perception and attitudes towards food colourants. For the first time, the findings of this paper report the effect of revealing information about an additive, which initially aroused disgust, and its influence on consumer perception.


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