Finite Element Computations of High Speed Viscous Compressible Flows

Finite Element Computations of High Speed Viscous Compressible Flows PDF Author: Oubay Hassan
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages :

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Finite Element Computations of High Speed Viscous Compressible Flows

Finite Element Computations of High Speed Viscous Compressible Flows PDF Author: Oubay Hassan
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages :

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A Contribution to the Finite Element Analysis of High-Speed Compressible Flows and Aerodynamics Shape Optimization

A Contribution to the Finite Element Analysis of High-Speed Compressible Flows and Aerodynamics Shape Optimization PDF Author: Mohammad Kouhi
Publisher:
ISBN:
Category :
Languages : en
Pages : 111

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Book Description
This work covers a contribution to two most interesting research elds in aerodynamics, the fi nite element analysis of high-speed compressible flows (Part I) and aerodynamic shape optimization (Part II). The fi rst part of this study aims at the development of a new stabilization formulation based on the Finite Increment Calculus (FIC) scheme for the Euler and Navier-Stokes equations in the context of the Galerkin nite element method (FEM). The FIC method is based on expressing the balance of fluxes in a spacetime domain of nite size. It is tried to prevent the creation of instabilities normally presented in the numerical solutions due to the high convective term and sharp gradients. In order to overcome the typical instabilities happening in the numerical solution of the high-speed compressible flows, two stabilization terms, called streamline term and transverse term, are added through the FIC formulation in space-time domain to the original conservative equations of mass, momentum and energy. Generally, the streamline term holding the direction of the velocity is responsible for stabilizing the spurious solutions produced from the convective term while the transverse term smooths the solution in the high gradient zones. An explicit fourth order Runge-Kutta scheme is implemented to advance the solution in time. In order to investigate the capability of the proposed formulation, some numerical test examples corresponding to subsonic, transonic and supersonic regimes for inviscid and viscous flows are presented. The behavior of the proposed stabilization technique in providing appropriate solutions has been studied especially near the zones where the solution has some complexities such as shock waves, boundary layer, stagnation point, etc. Although the derived methodology delivers precise results with a nearly coarse mesh, the mesh refinement technique is coupled in the solution to create a suitable mesh particularly in the high gradient zones. The comparison of the numerical results obtained from the FIC formulation with the reference ones demonstrates the robustness of the proposed method for stabilization of the Euler and Navier-Stokes equations. It is observed that the usual oscillations occur in the Galerkin FEM, especially near the high gradient zones, are cured by implementing the proposed stabilization terms. Furthermore, allowing the adaptation framework to modify the mesh, the quality of the results improves signi cantly. The second part of this thesis proposes a procedure for aerodynamic shape optimization combining Genetic Algorithm (GA) and mesh re nement technique. In particular, it is investigated the e ect of mesh re nement on the computational cost and solution accuracy during the process of aerodynamic shape optimization. Therefore, an adaptive remeshing technique is joined to the CFD solver for the analysis of each design candidate to guarantee the production of more realistic solutions during the optimum design process in the presence of shock waves. In this study, some practical transonic airfoil design problems using adap- tive mesh techniques coupled to Multi-Objective Genetic Algorithms (MOGAs) and Euler flow analyzer are addressed. The methodology is implemented to solve three practical design problems; the fi rst test case considers a reconstruction design optimization that minimizes the pressure error between a prede ned pressure curve and candidate pressure distribution. The second test considers the total drag minimization by designing airfoil shape operating at transonic speeds. For the final test case, a multi-objective design optimization is conducted to maximize both the lift to drag ratio (L/D) and lift coe cient (Cl). The solutions obtained with and without adaptive mesh re nement are compared in terms of solution accuracy and computational cost. These design problems under transonic speeds need to be solved with a ne mesh, particularly near the object, to capture the shock waves that will cost high computational time and require solution accuracy. By comparison of the the numerical results obtained with both optimization problems, the obtainment of direct bene ts in the reduction of the total computational cost through a better convergence to the final solution is evaluated. Indeed, the improvement of the solution quality when an adaptive remeshing technique is coupled with the optimum design strategy can be judged.

Mathematical and Computational Methods for Compressible Flow

Mathematical and Computational Methods for Compressible Flow PDF Author: Miloslav Feistauer
Publisher: Oxford University Press, USA
ISBN: 9780198505884
Category : Computers
Languages : en
Pages : 560

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Book Description
This book is concerned with mathematical and numerical methods for compressible flow. It aims to provide the reader with a sufficiently detailed and extensive, mathematically precise, but comprehensible guide, through a wide spectrum of mathematical and computational methods used in Computational Fluid Dynamics (CFD) for the numerical simulation of compressible flow. Up-to-date techniques applied in the numerical solution of inviscid as well as viscous compressible flow on unstructured meshes are explained, thus allowing the simulation of complex three-dimensional technically relevant problems. Among some of the methods addressed are finite volume methods using approximate Riemann solvers, finite element techniques, such as the streamline diffusion and the discontinuous Galerkin methods, and combined finite volume - finite element schemes. The book gives a complex insight into the numerics of compressible flow, covering the development of numerical schemes and their theoretical mathematical analysis, their verification on test problems and use in solving practical engineering problems. The book will be helpful to specialists coming into contact with CFD - pure and applied mathematicians, aerodynamists, engineers, physicists and natural scientists. It will also be suitable for advanced undergraduate, graduate and postgraduate students of mathematics and technical sciences.

An Adaptive Remeshing Finite Element Method for High Speed Compressible Flows Using Quadrilateral and Triangular Elements

An Adaptive Remeshing Finite Element Method for High Speed Compressible Flows Using Quadrilateral and Triangular Elements PDF Author: Gururaja R. Vemaganti
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 334

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Numerical Simulation of Incompressible Viscous Flow

Numerical Simulation of Incompressible Viscous Flow PDF Author: Roland Glowinski
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110785056
Category : Mathematics
Languages : en
Pages : 236

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Book Description
This book on finite element-based computational methods for solving incompressible viscous fluid flow problems shows readers how to apply operator splitting techniques to decouple complicated computational fluid dynamics problems into a sequence of relatively simpler sub-problems at each time step, such as hemispherical cavity flow, cavity flow of an Oldroyd-B viscoelastic flow, and particle interaction in an Oldroyd-B type viscoelastic fluid. Efficient and robust numerical methods for solving those resulting simpler sub-problems are introduced and discussed. Interesting computational results are presented to show the capability of methodologies addressed in the book.

Finite Element Methods for Viscous Incompressible Flows

Finite Element Methods for Viscous Incompressible Flows PDF Author: Max D. Gunzburger
Publisher: Elsevier
ISBN: 0323139825
Category : Technology & Engineering
Languages : en
Pages : 292

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Book Description
Finite Element Methods for Viscous Incompressible Flows examines mathematical aspects of finite element methods for the approximate solution of incompressible flow problems. The principal goal is to present some of the important mathematical results that are relevant to practical computations. In so doing, useful algorithms are also discussed. Although rigorous results are stated, no detailed proofs are supplied; rather, the intention is to present these results so that they can serve as a guide for the selection and, in certain respects, the implementation of algorithms.

A New Finite Element Approach: Progress in Inviscid Flow Computations

A New Finite Element Approach: Progress in Inviscid Flow Computations PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20

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The Finite Element Method for Fluid Dynamics

The Finite Element Method for Fluid Dynamics PDF Author: O. C. Zienkiewicz
Publisher: Elsevier
ISBN: 008045559X
Category : Mathematics
Languages : en
Pages : 457

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Book Description
Dealing with general problems in fluid mechanics, convection diffusion, compressible and incompressible laminar and turbulent flow, shallow water flows and waves, this is the leading text and reference for engineers working with fluid dynamics in fields including aerospace engineering, vehicle design, thermal engineering and many other engineering applications. The new edition is a complete fluids text and reference in its own right. Along with its companion volumes it forms part of the indispensable Finite Element Method series.New material in this edition includes sub-grid scale modelling; artificial compressibility; full new chapters on turbulent flows, free surface flows and porous medium flows; expanded shallow water flows plus long, medium and short waves; and advances in parallel computing. - A complete, stand-alone reference on fluid mechanics applications of the FEM for mechanical, aeronautical, automotive, marine, chemical and civil engineers. - Extensive new coverage of turbulent flow and free surface treatments

The Finite Element Method, Fluid Dynamics

The Finite Element Method, Fluid Dynamics PDF Author: O. C. Zienkiewicz
Publisher: Wiley
ISBN: 9780470395066
Category : Technology & Engineering
Languages : en
Pages : 0

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Book Description
Coverage of the whole range of fluid dynamics - including incompressible slow viscous flow, high-speed supersonic flows, shallow water flow, ocean waves, and metal and plastic forming. Up-to-date material on the Characteristic Galerkin Method. New methodologies for dealing with supersonic and hypersonic behaviours. New material on free surface phenomena. "...the publication of the first edition was an epoch making event...it is written by...the greatest theorist of the subject. If you are serious about finite elements, this is a book that you simply cannot afford to be without." International Journal of Numerical Methods in Engineering. "...the pre-eminent reference work on finite element analysis." Applied Mechanical Review. "...a very good book...presentation is first class...will be of great assistance to all engineers and scientists interested in the method...a very commendable piece of work.—"Journal of the British Society for Strain Measurement.

Finite Element Computation of a Viscous Compressible Free Shear Flow Governed by the Time Dependent Navier-Stokes Equations

Finite Element Computation of a Viscous Compressible Free Shear Flow Governed by the Time Dependent Navier-Stokes Equations PDF Author: Charlie H. Cooke
Publisher:
ISBN:
Category : Finite element method
Languages : en
Pages : 116

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