1,721,662 research outputs found
Investigation on meshfree particle methods for fluid structure interaction problems
No full textThe research aims to investigate the application of meshfree particle methods for computational modelling of the Fluid Structure Interaction problems with particular emphasis on flow around cylindrical objects and aerofoils. For this purpose, a solution scheme has been developed for solving incompressible, viscous Navier-Stokes (N-S) equations over meshfree particles. Spatial derivatives appearing in N-S equations are dealt with using radial basis functions infinite difference mode (RBF-FD). A comparative study has also been conducted between implicit and explicit in time solution schemes for N-S equations over meshfree nodes. Subsequently, a coupled meshfree and mesh-based solution scheme is proposed, over hybrid fluid grid, for incompressible, viscous flow around stationary as well as moving objects. The aim of this coupled solver is to provide efficiency and flexibility by combining the advantages of both meshfree and mesh-based methods. The coupled solution scheme suggests generating a body conformal meshfree nodal cloud around the solid body in the near field. A static Cartesian grid surrounds the meshfree cloud in the far field. The Meshfree nodes offer flexibility in dealing with solid motion by moving along the solid boundary without necessitating re-meshing. The Cartesian grid, on the other hand, provides improved performance by allowing faster computation owing to the use of efficient mesh based method. Flow equations, in Arbitrary Lagrangian-Eulerian (ALE) formulation, are solved using RBF-FD based scheme over moving meshfree nodes. Conventional infinite differencing is used over static Cartesian grid for flow equations in Eulerian formulation. The coupled solution scheme, on hybrid grid, is employed for closely coupled Fluid Structure Interaction problems. The equations for solid motion are solved using classical Runge-Kutta method. Close coupling between fluid and structural solvers is realized by a sub-iterative prediction-correction algorithm. In order to reduce computational overhead due to sub-iterations, only near field flow (in meshfree zone) is solved during inner iterations. Solution over full fluid domain is sought during outer (time step) iterations only, when the convergence at fluidsolid interface has already been reached. The solution scheme is also applied for high Reynolds number problems. For this purpose, a stabilization term is included in the flow equations to suppress the spurious oscillations. The stabilization term is derived using vimomentum balance equation over control volume and applying higher order Taylor series expansion of momentum flux and fluid forces. In order to avoid ill-conditioning and accuracy problems related to RBF matrices in domains having varying nodal density, use of shape adaptive RBFs are proposed. In that, the shape parameter of the radial basis function is varied according to local nodal density. Moreover, adaptive sizing of influence domain has also been introduced to maintain suitable number of neighbouring particles. These adaptive techniques are found to be useful as they allow much finer nodal distribution at regions of interest enabling accurate capturing of flow gradients and leading to better results. The use of hybrid grid offers flexibility in dealing with moving boundaries. Moreover, in addition to allowing faster computing over Cartesian grid, it also enables using the reduced fluid domain during inner FSI iterations and therefore helps reduce the number of computations in the fluid domain during fluid-solid coupling. The solution scheme was tested for problems relating to flows around static as well as moving cylinders and aerofoils. Flow induced vibrations have been studied with one and two degrees of freedom. The results are found to be in good agreement with previous numerical work and experimental results
Long-term outcomes in revision powered endoscopic dacryocystorhinostomy
No full textAbstract not availableMohammad Javed Ali, Alkis James Psaltis, and Peter John Wormal
Low Reynolds number effect on energy extraction performance of semi-passive flapping foil
No full textIn this paper, 2-D numerical solution scheme is used to study the performance of semi-passive flapping foil flow energy harvester at Reynolds numbers ranging from 5000 to 50,000. The energy harvester comprises of NACA0015 airfoil which is supported on a translational spring and damper. An external sinusoidal pitch excitation is provided to the airfoil. Energy is extracted from the flow induced vibration of airfoil in translational mode. Movement of airfoil is accommodated in fluid domain by using a hybrid meshfree Cartesian fluid grid. A body conformal meshfree nodal cloud forms the near field domain, encompassing the airfoil. During the simulation, the solid boundary causes the motion of the meshfree nodal cloud, without necessitating re-meshing. In the far field, the static Cartesian grid encloses and partly overlaps the meshfree nodal cloud. A coupled mesh based and meshfree solution scheme is utilized to solve laminar flow, viscous, incompressible equations, in Arbitrary-Lagrangian-Eulerian (ALE) formulation, over a hybrid grid. Spatial discretization of flow equations is carried out using radial basis function in finite difference mode (RBF-FD) over meshfree nodes and conventional finite differencing over Cartesian grid. Stabilized flow momentum equations are used to avoid spurious fluctuations at high Reynolds numbers. A closely coupled, partitioned, sub-iteration method is used for fluid structure interaction. The study is focused to analyse the behaviour of flow energy harvesters at various Reynolds numbers. Effects of changing the translational spring stiffness and pitch activation frequency are also investigated. Instantaneous flow structures around the airfoil have been compared at different Reynolds numbers and pitch amplitudes. It is found that net power extracted by the system increases at high Reynolds numbers. Moreover, re-attachment of leading edge separation vortex plays an important role in their overall system performance.<br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
sj-docx-1-npx-10.1177_1934578X211031148 - Supplemental material for Antileishmanial Potential of Berberine Alkaloids From <i>Berberis glaucocarpa</i> Roots: Molecular Docking Suggests Relevant <i>Leishmania</i> Protein Targets
No full textSupplemental material, sj-docx-1-npx-10.1177_1934578X211031148 for Antileishmanial Potential of Berberine Alkaloids From Berberis glaucocarpa Roots: Molecular Docking Suggests Relevant Leishmania Protein Targets by Muhammad Alamzeb, Saqib Ali, Mamoon-Ur-Rashid, Behramand Khan, Ihsanullah, Adnan, Muhammad Omer, Asad Ullah, Javed Ali, William N. Setzer, Syed M. Salman, Ajmal Khan and Akram Shah in Natural Product Communications</p
sj-docx-2-npx-10.1177_1934578X211031148 - Supplemental material for Antileishmanial Potential of Berberine Alkaloids From <i>Berberis glaucocarpa</i> Roots: Molecular Docking Suggests Relevant <i>Leishmania</i> Protein Targets
No full textSupplemental material, sj-docx-2-npx-10.1177_1934578X211031148 for Antileishmanial Potential of Berberine Alkaloids From Berberis glaucocarpa Roots: Molecular Docking Suggests Relevant Leishmania Protein Targets by Muhammad Alamzeb, Saqib Ali, Mamoon-Ur-Rashid, Behramand Khan, Ihsanullah, Adnan, Muhammad Omer, Asad Ullah, Javed Ali, William N. Setzer, Syed M. Salman, Ajmal Khan and Akram Shah in Natural Product Communications</p
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Upwind skewed radial basis functions (USRBF) for solution of highly convective problems over meshfree nodes
No full textAn upwind skewed radial basis function (USRBF)-based solution scheme is presented for stabilized solutions of convection-dominated problems over meshfree nodes. The conventional, radially symmetric radial basis functions (RBFs) are multiplied with an upwinding factor which skews the RBFs toward the upwind direction. The upwinding factor is a function of flow direction, intensity of convection, size of local support domain, and nodal distribution. The use of USRBFs modifies the weight values such that the necessary artificial diffusion is added only along the flow direction, whereas the crosswind diffusion is avoided. Subsequently, these skewed radial basis functions are employed in finite difference mode (RBF-FD) for derivative approximation. The performance and accuracy of the proposed scheme is studied by solving convection–diffusion problems over uniform and random distribution of meshfree nodes with various convection intensities. The upwinding effectively suppresses non-physical perturbation in numerical solution of convection-dominated problems. The results show that significant improvement in accuracy can be achieved by using the proposed USRBF-based solution scheme, particularly at higher convection intensities
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