Mathematical and Computational Methods for Compressible Flow

Mathematical and Computational Methods for Compressible Flow
Author: Miloslav Feistauer
Publisher: Oxford University Press, USA
Total Pages: 560
Release: 2003
Genre: Computers
ISBN: 9780198505884

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 Investigation of Compressible Flows Over Open Cavities Including Shear Layer Thickness Effects

An Investigation of Compressible Flows Over Open Cavities Including Shear Layer Thickness Effects
Author: S. G. Kelly
Publisher:
Total Pages: 44
Release: 1984
Genre:
ISBN:

The mathematical modelling of the two dimensional compressible for over an open rectangular cavity is considered. The flow field is divided into three regions: (1) the two-dimensional compressible flow outside the cavity which is governed by a convective wave equation; (2) the two dimensional flow inside the cavity for which the mean flow is neglected and thus is governed by the wave equation; and (3) the shear layer spanning the cavity which is the major focus of the investigation. the work of Tam and Block is followed and a method for determining the discrete frequencies of shear layer oscillation is determined including shear layer thickness effects and assuming that the shear layer grows downstream. a line source placed at the trailing edge is used to model the trailing edge interaction process and the analysis of a shear layer excited by a reflected wave of arbitrary frequency is considered. Since the mean flow in the shear layer is nonuniform, standard stability procedures do not work. The nonparallel effects are assumed to be weak. The method of multiple scales is used to analyze the nonparallel stability of the shear layer. The stability characteristics of the shear layer are used in an equation developed by Tam and Block to predict discrete oscillation frequencies. The numerical methods for solving the equations are discussed. Originator-supplied keywords include: Open cavity flows; Nonparallel stability; and Multiple scales.

Numerical Simulation of Compressible Flow Using a Velocity/vorticity/pressure Formulation

Numerical Simulation of Compressible Flow Using a Velocity/vorticity/pressure Formulation
Author: Ben Chacon
Publisher:
Total Pages:
Release: 2013
Genre:
ISBN: 9781303791697

The fundamental equations for compressible flow are solved using a velocity - pressure - vorticity formulation producing a solution that satisfies continuity and vorticity definitions up to machine accuracy. Chapter 1 reviews many algorithms used to solve this problem. Unlike those methods, no pressure - velocity relation or artificial compressibility is assumed in the present formulation, so the equations for kinematics, pressure and momentum are decoupled independent building blocks in the iterative process. As a consequence, the resulting modular algorithm can be used directly for compressible or incompressible flows, contrasting with other current techniques. Moreover the present formulation also applies to two-dimensional and three-dimensional, structured and unstructured grids without any changes, even though only the two-dimensional version was implemented. In Chapter 2, the original formulation is described. A functional minimization technique is used to discretize the kinematics equations, mimicking continuous methods used in the field of functional analysis and providing a common framework to understand, model and implement the solution algorithm. Suitable preconditioning and radial interpolation techniques are employed to balance precision and computational speed. The Poisson equation for pressure is solved similarly by minimizing a suitable functional. The momentum equations are then solved using a finite volume approach adding a controlled amount of artificial viscosity according to mesh size and Reynolds number, resulting in a stable calculation. The vorticity is then obtained as the curl of the velocity. Temperature is similarly computed from the energy equation in an outer loop. Suitable adjustments to pressure and temperature enable the ideal gas equation to fit both the compressible and incompressible paradigmsSubsequent chapters deal with validation, applying the computer efficient implementation of the algorithm to a variety of well documented aerodynamic benchmark problems. Examples include compressible and incompressible flow, steady and unsteady problems and flow over cylinders and airfoils over a variety of Reynolds and subsonic Mach numbers.

A Unified View of Global Instabilities of Compressible Flow Over Open Cavities

A Unified View of Global Instabilities of Compressible Flow Over Open Cavities
Author:
Publisher:
Total Pages: 7
Release: 2005
Genre:
ISBN:

We report progress in our ongoing effort to compute and understand the three-dimensional instabilities (resonance) of open cavity flows from incompressible to supersonic speeds. In particular, our work is aimed at regimes where significant interactions occur between the shear layer spanning the cavity and the recirculating flow within the cavity, as encountered in many experiments and numerical simulations reported in the literature. Complementary methodologies for extracting information about global instabilities (including their receptivity and optimal control) of two- and three-dimensional cavity flows have been developed. We present here some sample calculations that show that for a low Mach number cavity with a length-to-depth ratio of two, the two-dimensional steady flow is unstable to three-dimensional (spanwise homogeneous) disturbances that consist of spanwise modulation of the recirculating vortex interior to the cavity. The oscillations are unstable over a narrow band of spanwise wavelengths comparable to the cavity depth. They are oscillatory in time, but with a very slow frequency that is about ten times slower than the incipient two-dimensional Rossiter instability. Instability seems to be related to cellular patterns observed in surface streamline patterns on cavity bottoms in some previous experiments.

Numerical Simulations Of Incompressible Flows

Numerical Simulations Of Incompressible Flows
Author: Mohamed M Hafez
Publisher: World Scientific
Total Pages: 708
Release: 2003-01-23
Genre: Mathematics
ISBN: 9814486396

This book consists of 37 articles dealing with simulation of incompressible flows and applications in many areas. It covers numerical methods and algorithm developments as well as applications in aeronautics and other areas. It represents the state of the art in the field.