Papers by Keyword: Incompressible Flow

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Authors: P.J.S.A. Ferreira de Sousa, Isabel Malico, Gérson Fernandes
Abstract: A compact finite differences method is used to calculate two-dimensional viscous flows through complex geometries. The immersed boundaries are set through body forces that allow for the imposition of boundary conditions that coincide with the computational grid. Two different flow configurations are simulated. First, the flow through a row of cylinders with square cross-sections is calculated and used as a validation study. The computed average drag coefficient and Strouhal number are compared to data available in the literature, showing a good agreement between the results. The second flow configuration analyzed is the flow through a porous matrix composed of equal size staggered square cylinders. Flow visualization results are shown and various flow regimes identified. Different inlet boundary conditions are compared. The drag coefficient is larger when a uniform inlet velocity is prescribed and the variability between cylinders is lower.
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Authors: Xia Wan Zhang, Jie Mao, Liang Yu
Abstract: A solver for MHD turbulent flow and a new RANS model based on k-ω model in the open source toolbox OpenFOAM are developed to investigate magnetohydrodynamic (MHD) turbulent flow. Two electro-magnetic terms in the k and ω transport equations are added to include magnetohydrodynamic (MHD) effects. The modified k-ω is validated by simulating MHD turbulent duct flow. Time-averaged velocity and turbulent kinetic energy profiles simulated by standard k-ω and the modified k-ω in the fully developed section are both reported. The results compare fairly with those obtained from DNS data. A difference of 8.4% in is found between the modified k-ω and DNS, but the RANS model only uses 0.4% of the DNS computation time.
253
Authors: M. Rizwan Malik, Tie Lin Shi, Zi Rong Tang, Guang Lan Liao
Abstract: Multiphysics numerical simulation (MPNS) has certainly acquired a wide acceptance in the modeling, designing and fabrication fields and has been validated for various research applications. But it is important that the method should be thoroughly understood by students of the various fields. Keeping this aim in view, we demonstrate here the MPNS process as applied in several fields, such as: electrostatics, mechanics, chemistry, heat transfer and fluid flow. Four tasks are performed for fifteen hours in order to analyze simulation approaches such as modeling with geometrical parameters, meshing, solution and post-processing methods. Convection, buoyancy effects, microfiltration and flow analysis are investigated. This comprehensive study will enhance appreciation of the basic concepts of design and dimensioning of an object in MEMS for engineers, and help to guide workers in these fields when performing these tasks.
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Authors: Thamy C. Hayashi, Isabel Malico, J.F.C. Pereira
Abstract: The influence of inserting ceramic foam in a pipe with a 1:4 sudden expansion was numerical investigated. The foam, with a thickness to diameter ratio of 0.60, was positioned at different distances from the sudden pipe expansion wall. Three different porosities were analyzed (10, 20 and 60 pores per inch) for pore Reynolds numbers in the range of 20-400, corresponding to pipe Reynolds numbers of 2400 to 22000 in the pipe section upstream the sudden expansion. Predictions of the sudden pipe expansion cavity assuming laminar flow within the foam yield the penetration of the separated flow region into the foam. Considering turbulent flow in the porous foam and the model of Pedras and Lemos [14] prevents this penetration. The numerical and physical models used could not reproduce completely the foam influence on the separated turbulent flow region between the sudden pipe expansion and the foam inlet.
616
Authors: Hai Jun Gong, Yang Liu, Xue Yi Fan, Da Ming Xu
Abstract: For a clear and comprehensive opinion on segregated SIMPLE algorithm in the area of computational fluid dynamics (CFD) during liquid processing of materials, the most significant developments on the SIMPLE algorithm and its variants are briefly reviewed. Subsequently, some important advances during last 30 years serving as increasing numerical accuracy, enhancing robustness and improving efficiency for Navier–Stokes (N-S) equations of incompressible fluid flow are summarized. And then a so-called Direct-SIMPLE scheme proposed by the authors of present paper introduced, which is different from SIMPLE-like schemes, no iterative computations are needed to achieve the final pressure and velocity corrections. Based on the facts cited in present paper, it conclude that the SIMPLE algorithm and its variants will continue to evolve aimed at convergence and accuracy of solution by improving and combining various methods with different grid techniques, and all the algorithms mentioned above will enjoy widespread use in the future.
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Authors: Sterian Danaila, Delia Teleaga, Luiza Zavalan
Abstract: This paper presents an application of the Finite Volume Particle Method to incompressible flows. The two-dimensional incompressible Navier-Stokes solver is based on Chorin’s projection method with finite volume particle discretization. The Finite Volume Particle Method is a meshless method for fluid dynamics which unifies advantages of particle methods and finite volume methods in one scheme. The method of manufactured solutions is used to examine the global discretization error and finally a comparison between finite volume particle method simulations of an incompressible flow around a fixed circular cylinder and the numerical simulations with the CFD code ANSYS FLUENT 14.0 is presented.
72
Authors: Li Wei Song, Song Ping Wu
Abstract: In this work, a ghost cell immersed boundary method is applied to the numerical simulation of a uniform flows over a circular cylinder and two circular cylinders in tandem arrangement. The Navier-Stokes equations are solved using an implicit fractional step method employed on collocated arrangement variables. Immersed boundary method permit the use of structured Cartesian meshes to simulate flows involving complex boundaries. The shedding of vortices and flow interference between two circular cylinders in tandem arrangement are investigated numerically. The calculations are validated against the experimental and numerical results obtained by other researchers to prove the accuracy and effectiveness.
478
Authors: Tian Wen Dong, Shun Liang Jiang, Xing Yuan Huang, He Sheng Liu, Qiang Qiang Huang
Abstract: Based on the incompressible smoothed particle hydrodynamics (ISPH) method, a program was developed to simulate the non-Newtonian fluid flow in the mixing section of a single screw extruder. The transverse flow in the extruder is mimicked by one 2-D lid-driven cavity flow. The mirror particles are used to treat boundary. The power-law model is used to calculate the viscosity of the fluid. The shear-thinning, the shear-thickening and Newtonian fluid in the single screw extruder are simulated and deeply analyzed. Through comparing the velocity profile along the centre of screw extruder with the theoretical solution, this method has been proven to be accurate and effective. It laid the foundation for the simulating of the more complex 3-D model.
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Authors: Christina G. Georgantopoulou, Feras Abbas Ali, Nikolaos S. Vasilikos, George A. Georgantopoulos
Abstract: The oil transportation among the Middle East Countries and especially in Bahrain is extended and demands high performance and quality, reducing the leakages as well as the resistance to the flow simultaneously. Due to this reason in the present paper the crude oil dynamic behavior in a channel is studied in order to present valuable information for the flow variables and the separation zones according to various discharge or aspect ratios. The numerical approach is developed for T-junction channels due to the high oil and gas applications in the region, in order to transfer the oil from the source to the refinery. The most important aspect is the specification of the recirculation zones and stagnation points according to the flow velocity. The flow is steady, laminar and incompressible, while uniform, un-uniform and adaptive grids of various sizes have been generated in order to produce the desire accuracy even in high aspect ratio geometries. The results presents satisfied accuracy concerning the literature, while these are valuable data for the oil and gas companies in pipelines construction as well as to control operation issues.
15
Authors: P.J.S.A. Ferreira de Sousa, Isabel Malico, Gérson Fernandes
Abstract: This paper is centred on a compact finite differences method for the calculation of two-dimensional viscous flows through complex geometries. The immersed boundaries are set through body forces that allow for the imposition of boundary conditions that coincide with the computational grid. Two different flow configurations are simulated. First, the flow past a cylinder with square cross-section inside a plane channel is calculated. The computed average drag coefficient and Strouhal number are compared to data available in the literature. The agreement between the results is good. The second flow configuration analyzed is the flow through a porous matrix composed of equal size staggered square cylinders. Flow visualization results are shown. The work presented in this paper illustrates the potential of the immersed boundary method in general and of this implementation in particular to simulate the flow through porous matrices.
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