698 research outputs found
MHD Darcy-Forchheimer Slip Flow in a Porous Medium with Variable Thermo-Physical Properties
No full textAbstract: MHD Darcy-Forchheimer Slip Flow in a Porous Medium with Variable Thermo-Physical Properties was studied. The governing partial differential equations are converted into nonlinear ordinary differential equations using a similarity transformation and solved numerically. The variable and thermal conductivity were studied. Different physical parameters’ effects on temperature, velocity and concentration distribution are studied. The effects of Darcy-Forchheimer parameter, suction/blowing parameter, velocity slip and thermal slip parameter on the velocity, temperature and mass transfer rates nature are examined with the aid of graphs. Schmidt number and Soret number effect are also presented. The results shows that when the porosity parameter is increased, the velocity of the fluid decrease, while temperature profile and skin friction decreases. Also increasing the velocity slip parameter result in increase in velocity and Nusselt number whereas the concentration decreases in same case. Also the temperature at a point decreases with increase in thermal slip parameter while the skin friction decrease in both cases.
Keywords: Darcy-Forchheimer, Porous medium, Slip flow, Magneto-hydrodynamics (MHD), variable viscosity, thermal conductivity.
Title: MHD Darcy-Forchheimer Slip Flow in a Porous Medium with Variable Thermo-Physical Properties
Author: A.L. Panya, O. A. Akinyemi, A.M. Okedoye
International Journal of Mechanical and Industrial Technology
ISSN 2348-7593 (Online)
Vol. 10, Issue 2, October 2022 - March 2023
Page No: 30-43
Research Publish Journals
Website: www.researchpublish.com
Published Date: 16-February-2023
DOI: https://doi.org/10.5281/zenodo.7646344
Paper Download Link (Source)
https://www.researchpublish.com/papers/mhd-darcy-forchheimer-slip-flow-in-a-porous-medium-with-variable-thermo-physical-propertiesInternational Journal of Mechanical and Industrial Technology, ISSN 2348-7593 (Online), Research Publish Journals, Website: www.researchpublish.co
Flow in Fractured Media: a Darcy-Stokes-Brinkman Modelling Approach
No full textCoupling between porous media and free flow is widely present in many applications. In fractured reservoirs, fractures are often treated as parallel (smooth) plates, between which the flow is assumed to be steady state fully developed, with no-slip boundary condition. Under these assumptions, the Darcy law is employed inside fractures with permeability (Kf ) as a quadratic function of aperture (a), i.e., Kf = a2/12. Although this model is a rough simplification of real rock fractures, it is still widely used in subsurface flowmodelling. This study aims to investigate the validity range of the so-called local cubic law (LCL) by using a Darcy-Stokes-Brinkman model in which a unified formulation describes the Stokes flow in the free-flow sub-domain and Darcy flow in the porous sub-domain. Two simulation strategies are developed: a sequentially coupled approach, and a fully coupled approach. The nonlinear velocity profiles inside the free flow require enough grid resolution to be captured. As such, the grid resolution sensitivity is presented. More importantly, the permeability contrast between the two media is found to be an important factor for the applicability of the LCL (Darcy-Darcy) approach. A threshold of 10−7 is found, below which the difference between the two modelling approaches is negligible, and above which the LCL model no longer provide reasonable results
Shields-Darcy pipingmodel. Verschilanalyse met Sellmeijer en D-GeoFlow.
No full textHydraulic Structures and Flood Ris
A conservative hybrid method for darcy flow
No full textWe present a hybrid mimetic spectral element formulation for Darcy flow. The discrete representations for (1) conservation of mass, and (2) inter-element continuity, are topological relations that lead to sparse matrix systems. These constraints are independent of the element size and shape, and thus invariant under mesh transformations. The resultant algebraic system is extremely sparse even for high degree polynomial basis. Furthermore, the system can be efficiently assembled and solved for each element separately.Aerodynamic
A multigrid multilevel Monte Carlo method for transport in the Darcy–Stokes system
No full textA multilevel Monte Carlo (MLMC) method for Uncertainty Quantification (UQ) of advection-dominated contaminant transport in a coupled Darcy–Stokes flow system is described. In particular, we focus on high-dimensional epistemic uncertainty due to an unknown permeability field in the Darcy domain that is modelled as a lognormal random field. This paper explores different numerical strategies for the subproblems and suggests an optimal combination for the MLMC estimator. We propose a specific monolithic multigrid algorithm to efficiently solve the steady-state Darcy–Stokes flow with a highly heterogeneous diffusion coefficient. Furthermore, we describe an Alternating Direction Implicit (ADI) based time-stepping for the flux-limited quadratic upwinding discretization for the transport problem. Numerical experiments illustrating the multigrid convergence and cost of the MLMC estimator with respect to the smoothness of permeability field are presented.AerodynamicsNumerical Analysi
Analysis of Multiphase Non-Darcy Flow in Porous Media
No full textRecent laboratory studies and analyses (Lai et al. Presented at the 2009 Rocky Mountain Petroleum Technology Conference, 14-16 April, Denver, CO, 2009) have shown that the Barree and Conway model is able to describe the entire range of relationships between flow rate and potential gradient from low- to high-flow rates through porous media. A Buckley and Leverett type analytical solution is derived for non-Darcy displacement of immiscible fluids in porous media, in which non-Darcy flow is described using the Barree and Conway model. The comparison between Forchheimer and Barree and Conway non-Darcy models is discussed. We also present a general mathematical and numerical model for incorporating the Barree and Conway model in a general reservoir simulator to simulate multiphase non-Darcy flow in porous media. As an application example, we use the analytical solution to verify the numerical solution for and to obtain some insight into one-dimensional non-Darcy displacement of two immiscible fluids with the Barree and Conway model. The results show how non-Darcy displacement is controlled not only by relative permeability, but also by non-Darcy coefficients, characteristic length, and injection rates. Overall, this study provides an analysis approach for modeling multiphase non-Darcy flow in reservoirs according to the Barree and Conway model.Engineering, ChemicalSCI(E)EI7ARTICLE2205-2238
Darcy Ribeiro : a trajectory (1944-1982)
No full textOrientador: Guilhermo Raul RubenTese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias HumanasResumo: Esta tese analisa a trajetória de Darcy Ribeiro entre os anos de 1944 e 1982, perÃodo que corresponde à sua atuação, primeiro como antropólogo, depois como polÃtico e exilado, e durante o qual foi elaborada a quase totalidade de sua obra antropológica. Personagem dos mais importantes na consolidação da antropologia brasileira dos anos 50 e autor de livros de repercussão internacional, sua trajetória tornou-se, no entanto, particularmente a partir da segunda metade da década de 70, de certa forma deslocada em relação a boa parte do trabalho realizado por antropólogos no paÃs, o que acabou por minimizar sua influência intelectual no cenário antropológico brasileiro. Isto se explica não só por Darcy ter valorizado uma intensa participação polÃtica junto ao Estado, iniciada ainda na década de 60, como também por ter sido o autor de uma antropologia fortemente marcada por uma experiência especÃfica vivenciada por ele, como exilado, em diversos paÃses da América Latina. Desta forma, ao acompanhar o seu percurso, busco entender como se articulam o discurso, a prática e a obra de Darcy Ribeiro no perÃodo em questão, a partir de um campo empÃrico especÃfico. Refiro-me ao acervo pessoal de Darcy Ribeiro, atualmente sob os auspÃcios da Fundação Darcy Ribeiro, cuja documentação, praticamente inexplorada no campo das ciências sociais, constitui a fonte da maior parte das discussões realizadas no presente trabalhoAbstract: This thesis analyzes the path made by Darcy Ribeiro from 1944 to 1982, period of time which corresponds to his activity, first of all as an anthropologist, and then as a politician and as a refugee. And it was mostly during this period that almost all of his anthropological work was written. He was one of the most important characters in the consolidation of the Brazilian anthropology from the 50â?¿s and he was the author of books with international importance. His path was, nevertheless, different, in a certain way, from the work done by other anthropologists in the country, especially after the middle of 70â?¿s. With this attitude, his intellectual influence in the Brazilian anthropological group was minimized. We can understand that by the fact that Darcy had an intense political participation in the government, starting in the beginning of the 60â?¿s and also by being an author of an anthropology designed by his experience as a refugee in many Latin America countries. So, by following his path, I try to understand how his speech, his practice and his work were articulated during these years. This research is based on a specific field research. Iâ?¿m talking about Darcy Ribeiroâ?¿s personal archive, nowadays supervised by the Darcy Ribeiroâ?¿s Foundation. These documents, which are practically unexplored in the social sciences studies, are the major source of all the discussions done in this workDoutoradoCiencias SociaisDoutor em Ciências Sociai
Drawn Together by M. Le
No full textLe, Minh. Drawn Together. Illustrated by Dan Santat, Disney Hyperion, 2018. Drawn Together is a work of art created by Minh Le, author of award winning, Let Me Finish!, and illustrated by Caldecott Medalist, Dan Santat. This beautiful story depicts the cultural and linguistic divide between a young boy and his grandfather. The book invites the reader to walk alongside these two characters as they struggle with their differences only to stumble upon their similarities. Bringing together two generations of artists, the story revels in the characters’ imaginations as they create a vivid world of artistic adventures and compassion. Inhibited by the linguistic barriers that once isolated the characters, Minh Le’s limited, yet well crafted, text serves to support Dan Santat’s captivating illustrations that “draw” the grandfather and young boy closer. Detailed facial expressions and rich illustrations heighten the reading experience and weave together a story that both literally and metaphorically bridges the space between a grandfather and his grandson. Whether you are curling up with young ones at home or searching for a beautiful book for your classroom library, look no further. This one is guaranteed to draw you in! Highly recommended: 4 out of 4 StarsReviewer: Darcy Courtland Darcy Courtland loves a good picture book! After seven years in the classroom, Darcy has returned to the University of Alberta to pursue a PhD in Elementary Education. Always up for a new adventure, Darcy is excited to be furthering her education in language and literacy and Indigenous education
The Darcy method for Topology Optimisation of pressure actuated compliant mechanisms
No full textThis work introduces a new method to deal with design dependent pressure loads in Topology Optimisation (TO) using the SIMP material model. A pronounced focus is on optimising pressure actuated compliant mechanisms. The difficulty herein is the interpretation of the pressure boundary in a TO design. In TO the boundaries are blurry, because of the filtering of the design variables, which is necessary to prevent checkerboarding. Another reason why the boundary is poorly defined is that the optimisation starts from an equally distributed grey, where black and white respectively are solid and void, so the boundary is either the domain boundary or not defined in early iterations of the optimisation. The methods proposed in literature often try to find the void-solid interface exposed to the pressure source to apply the loading from a pressure line directly. The method proposed in this work, appropriately called the Darcy method, first calculates the pressure field by using Darcy's law governing the flow through porous media and the associated pressure drop. A flow coefficient is introduced that decreases if the virtual element density increases. This results in a design dependent pressure field that can be solved using the Finite Element Method (FEM), which can then be translated to consistent nodal forces that are applied to the TO problem. A drainage coefficient has also been introduced to make sure that the pressure is drained entirely to the environment pressure over the first encountered void-solid interface exposed to the pressure source. The Darcy method has proven to function well in several test cases. The method has been thoroughly tested using several parameter sweeps on a clamping problem objective. The parameters whose influence is examined are: the initial condition, the density threshold value, flow coefficient gradient at the threshold, output spring stiffness and the volume fraction. Subsequently, some alternative TO problems are solved showing the diversity of the method. In perspective of future research, the Darcy method can function as a great tool to research load sensitivities by tuning the pressure field control parameters. The extension of the Darcy method to 3D or to several load cases comes naturally but has not been tested in this work, this is also recommended for future research.Mechanical Engineering | Precision and Microsystems Engineerin
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