Computational Fluid Dynamics: Principles and Applications, Third Edition presents students, engineers, and scientists with all they need to gain a solid understanding of the numerical methods and principles underlying modern computation techniques in fluid dynamics By providing complete coverage of the essential knowledge required in order to write codes or understand commercial codes, the book gives the reader an overview of fundamentals and solution strategies in the early chapters before moving on to cover the details of different solution techniques

	This updated edition includes new worked programming examples, expanded coverage and recent literature regarding incompressible flows, the Discontinuous Galerkin Method, the Lattice Boltzmann Method, higher-order spatial schemes, implicit Runge-Kutta methods and parallelization

	An accompanying companion website contains the sources of 1-D and 2-D Euler and Navier-Stokes flow solvers (structured and unstructured) and grid generators, along with tools for Von Neumann stability analysis of 1-D model equations and examples of various parallelization techniques



	
		Will provide you with the knowledge required to develop and understand modern flow simulation codes
	
		Features new worked programming examples and expanded coverage of incompressible flows, implicit Runge-Kutta methods and code parallelization, among other topics
	
		Includes accompanying companion website that contains the sources of 1-D and 2-D flow solvers as well as grid generators and examples of parallelization techniques

Computational Fluid Dynamics: Principles and Applications Ed. 3

The Kriging-based genetic algorithm is applied to aerodynamic design problems. The Kriging model, one of the response surface models, represents a relationship between the objective function (output) and design variables (input) using stochastic process. The kriging model drastically reduces the computational time required for objective function evaluation in the optimization (optimum searching) process. ‘Expected improvement (EI)’ is used as a criterion to select additional sample points. This makes it possible not only to improve the accuracy of the response surface but also to explore the global optimum efficiently. The functional analysis of variance (ANOVA) is conducted to evaluate the influence of each design variable and their interactions to the objective function. Based on the result of the functional ANOVA, designers can reduce the number of design variables by eliminating those that have small effect on the objective function. In this paper, the present method is applied to a two-dimensional airfoil design and the prediction of flap’s position in a multi-element airfoil, where the lift-to-drag ratio (L/D) is maximized.

Efficient Optimization Design Method Using Kriging Model

An efe cient and user-friendly approach is presented for constructing unstructured surface grids directly on three-dimensional CAD surface data. This system has the following features: 1 ) use of stereolithography data as surface dee nitions, that is, background grids for surface meshing; 2 ) automatic reconstruction of geometric features for initial front setup; 3 ) graphical user interface for easily controlling surface mesh density by inserting line sources and point sources on the surface; 4 ) adoption of an advancing-front surface triangulation method, which minimizes the necessity to divide the surface into a number of patches; and 5 ) outer boundary generation from templates in the system. The resulting system has been applied to several airplane cone gurations, and a notable reduction in turnaround time has been achieved. OMPUTATIONAL e uid dynamics (CFD) has become an indispensable design and analysis tool for many different types of geometric cone gurations and e eld regimes. The effectiveness of CFD usage in an actual design environment, however, is often limited. Most of these limitations are due to dife culties in generating the computational grid in a reasonable amount of time. The grid generation method should be automated as much aspossible. This is true for volume grid generation; it is now possible to create volume grids automatically. For the surface grid generation, however, user interventions are often required because the surface meshdirectlyaffectsthesolutionaccuraciesinCFDproblems,especiallyfortheaerodynamicevaluationofairplanes.Theaerodynamic performance is usually evaluated by surface values, such as pressure,skin friction,and so on.Thesevalues arehighlyaffected by the dee nition of sound geometric features, as well as the surface grid density. This suggests that surface grid generation methods must easily facilitate changes in grid density to obtain the best result with limited computational resources. Although controllability is often incompatible with the automation of grid generation, it is essential for surface meshing.

Direct Surface Triangulation Using Stereolithography Data

This paper presents an approach to the generation of unstructured surface meshes for Computer-Aided Design (CAD) surface models represented as lists of polygons with minimum user interventions. Stereolithography (STL) data are adopted as an interface between a CAD system and the surface grid generator. STL files often include problems such as overlapping surfaces, gaps, and intersections. They have to be revised quickly and automatically before the surface models are used for the background grid of the surface grid generation. In this paper, we describe an automatic revision method for use with STL-defined surface models. The advancing front method using geometric features is adopted directly on the modified STL surfaces. The capability of the method is demonstrated for several 3D surface models. Copyright © 2002 John Wiley & Sons, Ltd.

Surface triangulation for polygonal models based on CAD data

We discuss the unstructured grid method to compute flows around geometrically complex bodies having relative motions. To enhance the capability to treat complex geometries, a surface triangulation method using the advancing front method coupled with geometric feature extraction technique is described. Stereolithography (STL) data are adopted as an interface between a CAD system and the surface grid generator. Moving bodies are treated by the overset unstructured grid method. The capability of the method is demonstrated for simulations of an airplane separation process from a rocket booster and a hornet in flight. In the hornet simulation, the detailed components such as antennas, legs and a sting are all included in the computational grid. The flapping wings are treated by the overset unstructured grid method where a grid around the wing is overlapped on a stationary grid around the body of a hornet and moves with time to simulate the flapping motion

Some challenges of realistic flow simulations by unstructured grid CFD

A method for automatic generation of unstructured grids comprised of tetrahedra is discussed. Delaunay approach for tetrahedral grid generation is used. Particular attention is given to the boundary constraining problem. A simple and robust algorithm for the boundary constraining by successive use of boundary edge swapping, tetrahedral edge swapping and direct subdivision of tetrahedra is used. Small modifications allow to apply the method for viscous grid generation as well. Grid examples demonstrate efficiency of the method.

K. Nakahashi

Papers

A boundary recovery algorithm for Delaunay tetrahedral meshing