1,355,100 research outputs found
Dataset for "Improving the boundary efficiency of a compact finite difference scheme through optimising its composite template"
No full textThe data contains the ASCII, Tecplot and Matlab files used to generate the figures in the paper by Turner, Haeri & Kim (2016), 'Improving the boundary efficiency of a compact finite difference scheme through optimising its composite template', Computers & Fluids.</span
Hierarchical modelling of multiphase flows using fully resolved fixed mesh and PDF approaches
No full textFully–resolved simulations of multiphase flow phenomena and in particular particulate flow simulations are computationally expensive and are only feasible on massively parallel computer clusters. A 3D SIMPLE type pressure correction algorithm is implemented and extensively tested and parallelized to exploit the power of massively parallel computing clusters currently available. Domain decomposition and communication schemes applicable to a general unstructured or structured multi–block CFD codes are discussed and algorithms are proposed, implemented and tested. Several high–performance linear solvers and a multi–grid strategy for the current framework are implemented and the best types of solvers are identified.A 2D CFD code is developed by the author to test several possible fixed–mesh strategies. Variations of immersed boundary (IB) and fictitious domain (FD) methods are implemented and compared. FD methods are identified to have better properties especially if other transport phenomena are also considered. Therefore an FD method is adapted by the author for the SIMPLE type flow solvers and is extended to heat transfer problems. The method is extensively tested for the simulation of flow around stationary in addition to freely moving particles and forced motion where both natural and forced convection are considered. The method is used to study the flow and heat transfer around a stationary cylinder and a new high resolution correlation is devised for the estimation of the local Nusselt number curves. Free fall problem for a single circular cylinder is considered and the effects of internal heat generation and also long term behavior of single cold particle subject to natural convection are also studied in detail. A particle collision strategy is also adapted and tested for the particle–particle collision problems. The FD algorithm is extended to the 3D framework and the flow around single stationary sphere and also free fall of a single sphere are used to validate the FD algorithm in 3D.A unique polydispersed fluid-particle turbulent modelling process is reviewed and the closure problem for this framework is studied in detail. Two methods for the closure of the non–integer moments which results from the polydispersity of the particles are proposed namely PDF reconstruction using Laguerre polynomials and a unique direct method named Direct Fractional Method of Moments (DFMM). The latter is derived using the results of the fractional calculus by writing an equation for the fractional derivatives of the moment generating function. The proposed methods are tested on a number of problems consisting of analytical, experimental and DNS simulations to asses their validity and viability which shows that both methods provide accurate results with DFMM having more desirable properties
Airfoil noise reductions through leading edge serrations
No full textThis paper provides an experimental investigation into the use of leading edge (LE) serrations as a means of reducing the broadband noise generated due to the interaction between the aerofoil’s LE and impinging turbulence. Experiments are performed on a flat plate in an open jet wind tunnel. Grids are used to generate isotropic homogeneous turbulence. The leading edge serrations are in the form of sinusoidal profiles of wavelengths, ?, and amplitudes, 2h. The frequency and amplitude characteristics are studied in detail in order to understand the effect of LE serrations on noise reduction characteristics and are compared with straight edge baseline flat plates. Noise reductions are found to be insignificant at low frequencies but significant in the mid frequency range (500 Hz–8 kHz) for all the cases studied. The flat plate results are also compared to the noise reductions obtained on a serrated NACA-65 aerofoil with the same serration profile. Noise reductions are found to be significantly higher for the flat plates with a maximum noise reduction of around 9 dB compared with about 7 dB for the aerofoil. In general, it is observed that the sound power reduction level (?PWL) is sensitive to the amplitude, 2h of the LE serrations but less sensitive to the serration wavelength, ?. Thus, this paper sufficiently demonstrates that the LE amplitude acts as a key parameter for enhancing the noise reduction levels in flat plates and aerofoils
The effect of wavy leading edges on aerofoil-gust interaction noise
No full textHigh-order accurate numerical simulations are performed to investigate the effects of wavy leading edges (WLEs) on aerofoil–gust interaction (AGI) noise. The present study is based on periodic velocity disturbances predominantly in streamwise and vertical directions that are mainly responsible for the surface pressure fluctuation of an aerofoil. In general, the present results show that WLEs lead to reduced AGI noise. It is found that the ratio of the wavy leading-edge peak-to-peak amplitude (LEA) to the longitudinal wavelength of the incident gust (?g) is the most important factor for the reduction of AGI noise. It is observed that there exists a tendency that the reduction of AGI noise increases with LEA/?g and the noise reduction is significant for LEA/?g?0.3. The present results also suggest that any two different cases with the same LEA/?g lead to a strong similarity in their profiles of noise reduction relative to the straight leading-edge case. The wavelength of wavy leading edges (LEW), however, shows minor influence on the reduction of AGI noise under the present gust profiles used. Nevertheless, the present results show that a meaningful improvement in noise reduction may be achieved when 1.0?LEW/?g?1.5. In addition, it is found that the beneficial effects of WLEs are maintained for various flow incidence angles and aerofoil thicknesses. Also, the WLEs remain effective for gust profiles containing multiple frequency components. It is discovered in this paper that WLEs result in incoherent response time to the incident gust across the span, which results in a decreased level of surface pressure fluctuations, hence a reduced level of AGI noise
Conversation between three fishermen while fixing a fishnet
No full textThis is a recording of three men, Hamdani, Haeri and Safi'i at Haeri's house in the village of Pondok Perasi. Hamdani is 20 years old and unmarried. He was born and raised in Pondok Prasi. Haeri is a 35 year old man who was also born and raised in Pondok Prasi. He is married to a woman from eastern Lombok. Safi'i is a 23 year old man, born and raised in Pondok Prasi and is married to a girl from the same village. While Hamdani and Haeri never left the island, Safi'i had spent a few years in Malaysia and Kalimantan. The three speakers are still relative and all of them are fishermen.The three men are having a conversation while fixing Haeri's fishing net. They are talking about some topics such as the catch, Haeri's family problem, and Safi'i's story of catching a huge catfish when he was working in Kalimantan. The recording ends with Khairunnisa collecting metadata from the speakers.Herjan assisted with the recording. Video recorded on Canon VIXIA HFG40, audio on Marantz PMD561 with an Audio Technica AT8022 Stereo Microphone.Ampenan, Lombok, West Nusa Tenggara province, Indonesi
L’avenir de la profession d’avocat: Autour du Rapport Kami Haeri - Entretien avec Kami Haeri et Christophe Jamin et Sébastien Pimont
No full textDepuis plusieurs décennies maintenant, la profession d'avocat ne cesse de s'interroger sur ce qui la constitue et ses futurs possibles. Le premier livre d'ampleur remonte à 1967 et il est connu dans la profession sous la dénomination de « livre bleu ». Deux avocats y avaient plus spécialement attaché leur nom : Alain Tinayre et Denis de Ricci. En 2008, c'est un autre avocat de renom, Jean-Michel Darrois, qui remit un important rapport au Président de la République de l'époque. Celui-ci fut bientôt suivi, en 2011, par le rapport que rédigea Michel Prada, l'ancien président de l'Autorité des marchés financiers, sur le renforcement de la compétitivité de la place de Paris à la demande conjointe des ministres de la Justice et de l'Économie. Ces rapports ont d'ailleurs été suivis d'effets très concrets dans le sens d'une libéralisation des règles gouvernant la profession. Aujourd'hui, c'est à la demande de l'ancien garde des Sceaux, Jean-Jacques Urvoas, que l'avocat Kami Haeri a dirigé une commission sur ce même thème et remis un rapport intitulé « L'avenir de la profession d'avocat ». C'est de ce rapport qu'il est question dans la présente table ronde. Ses organisateurs ont voulu qu'on y aborde en particulier la question sous des angles susceptibles d'intéresser les juristes d'entreprise. Aussi y parle-t-on de secret professionnel ou du statut d'avocat en entreprise. Mais ne sont pas non plus oubliés les thèmes très actuels de la parité, de l'impact des nouvelles technologies sur l'exercice du droit, de l'interprofessionnalité ou encore de la formation. Sans oublier la question du bonheur qui se pose avec acuité au sein de la profession, sans être toujours abordée de front. [Résumé éditeur
Book review: race, education and citizenship: mobile Malaysians, British colonial legacies and a culture of migration by Sin Yee Koh
No full textIn Race, Education and Citizenship: Mobile Malaysians, British Colonial Legacies and a Culture of Migration, Sin Yee Koh offers a study of the migratory trajectories of tertiary-educated mobile Malaysian migrants and explores how the legacies of colonialism continue to impact upon the meanings of race, education and citizenship in this context. Fawzia Haeri Mazanderani strongly recommends this book to scholars interested in conceptualising migration and citizenship practices through a post-colonial lens
A mesoscopic description of polydispersed particle laden turbulent flows
No full textTurbulent polydispersed multiphase flows are encountered in many engineering and environmental applications and particularly in combustion applications, spray polydispersity is the norm rather than the exception. In this review we summarize the current state of Eulerian transport models for turbulent polydispersed particulate flows without size class discretization. The stochastic nature of both carrier and dispersed phase justifies a stochastic approach to describe the behavior of such systems. In this regard Brownian motion of a single microscopic particle is discussed to intuitively introduce the subject and point out the need for a stochastic representation of the phenomena based on stochastic differential equations (SDEs). Understanding the stochastic tools and mathematical framework based on Langevin equation is compulsory for the rest of this review but here we restrict our coverage to definitions and general remarks and give references for further readings. A stochastic foundation based on Langevin equation is defined for fluid and particle and derivation of the transport equation up to third order statistics without binning the particle diameter is discussed based on corresponding Fokker–Planck equation. Terms that appear in the process of contracting a probability density function (PDF) causing closure problems are identified. The Maximum entropy method is discussed as a tool for closure of particle acceleration terms in Eulerian transport equations followed by current closure issues such as realizability and generalit
A Sufi for a Secular Age: Reflecting on Muslim Modernity through the Life and Times of Shaykh Fadhlalla Haeri
No full textFadhlalla Haeri (b. 1937) is a contemporary Muslim figure best known for his spiritual commentaries on the Qur’an and his influential role as a ‘post-madhhab’ and ‘post-tariqa’ Sufi teacher. Born and brought up in the pilgrim city of Karbala by its religious elite, Haeri would go on to pursue a secular education in the West and a successful career in the booming Arab oil industry. But Haeri would inevitably withdraw from the business world and return to his roots by directing his efforts towards teaching the Qur’an, resulting in numerous publications and a worldwide network of students, with past and present communities especially established in the United States, Pakistan, England, Denmark, Sweden, Germany and South Africa. The purpose of this thesis is to observe Haeri’s life and works through the larger historical story of secularity as told by philosopher Charles Taylor. As a Sufi sage in a secular age, what Haeri offers us is a mirror, reflecting a period of time in which we are still so immersed that it eludes our ability to understand it in any comprehensive way. By looking at how his life and works both reflect and respond to our current epoch, the intention is to offer a compelling narrative of what can broadly be called Muslim modernity, together with the themes of ‘authority’ and ‘authenticity’ that can be seen to define it
A new implicit fictitious domain method for the simulation of flow in complex geometries with heat transfer
No full textA numerical algorithm for the simulation of flow past immersed objects with heat transfer is proposed and validated which conforms with the ideas of the fictitious domain method. A momentum source term is added to account for the presence of the object and a heat source term is proposed to impose the Dirichlet boundary condition on the surface of the objects. The algorithm is an implicit fictitious domain based method where the entire fluid-immersed object domain assumed to be an incompressible fluid. The flow domain is constrained to be divergence free, whereas a rigidity constraint is imposed on the body domain. Heat transfer is similarly considered by assuming that the object domain is filled with a fluid with different thermal properties. The SIMPLE algorithm with a collocated grid arrangement is used for pressure–velocity coupling which is unconditionally stable. The algorithm is validated by considering stationary, forced motion and freely moving objects with both isothermal and freely variable temperature inside the object. Good agreement with previous numerical and experimental studies for all the test cases is observed
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