NASA Technical Note


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Numerical Solution of the Equations for Compressible Laminar, Transitional, and Turbulent Boundary Layers and Comparisons with Experimental Data


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A numerical method for solving the equations for laminar, transitional, and turbulent compressible boundary layers for either planar or axisymmetric flows is presented. The fully developed turbulent region is treated by replacing the Reynolds stress terms with an eddy viscosity model. The mean properties of the transitional boundary layer are calculated by multiplying the eddy viscosity by an intermittency function based on the statistical production and growth of the turbulent spots. A specifiable turbulent Prandtl number relates the turbulent flux of heat to the eddy viscosity. A three-point implicit finite-difference scheme is used to solve the system of equations. The momentum and energy equations are solved simultaneously without iteration. Numerous test cases are compared with experimental data for supersonic and hypersonic flows; these cases include flows with both favorable and mildly unfavorable pressure gradient histories, mass flux at the wall, and traverse curvature.




Solutions of the Second-order Boundary-layer Equations for Laminar Incompressible Flow


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Use is made of self similarity approach and integral momentum technique to obtain solutions of Van Dyke's second-order boundary-layer equations for laminar incompressible flow. Accurate numerical solutions of the most general self similar equations are tabulated for the four second-order contributions due to vorticity interaction, displacement speed, longitudinal curvature, and transverse curvature. A limited number of closed form solutions are obtained which appear to have special significance at the point of first-order boundary-layer separation. In particular it is found that the displacement speed problem can proceed up to separation for only two values of the second-order pressure gradient. All other cases display an infinite discontinuity at this point. Numerical solutions of a large number of cases for the longitudinal and transverse curvature effects well support an identical conclusion. The integral momentum technique applied (a straight forward extension of the Karmen-Pohlhausen solutions) is found to be oversensitive to approximations and in the final analysis is rejected in favor of locally similar solutions. (Author).




Computational Fluid Mechanics and Heat Transfer, Second Edition


Book Description

This comprehensive text provides basic fundamentals of computational theory and computational methods. The book is divided into two parts. The first part covers material fundamental to the understanding and application of finite-difference methods. The second part illustrates the use of such methods in solving different types of complex problems encountered in fluid mechanics and heat transfer. The book is replete with worked examples and problems provided at the end of each chapter.







Nonlinear Partial Differential Equations


Book Description

Nonlinear Partial Differential Equations: A Symposium on Methods of Solution is a collection of papers presented at the seminar on methods of solution for nonlinear partial differential equations, held at the University of Delaware, Newark, Delaware on December 27-29, 1965. The sessions are divided into four Symposia: Analytic Methods, Approximate Methods, Numerical Methods, and Applications. Separating 19 lectures into chapters, this book starts with a presentation of the methods of similarity analysis, particularly considering the merits, advantages and disadvantages of the methods. The subsequent chapters describe the fundamental ideas behind the methods for the solution of partial differential equation derived from the theory of dynamic programming and from finite systems of ordinary differential equations. These topics are followed by reviews of the principles to the lubrication approximation and compressible boundary-layer flow computation. The discussion then shifts to several applications of nonlinear partial differential equations, including in electrical problems, two-phase flow, hydrodynamics, and heat transfer. The remaining chapters cover other solution methods for partial differential equations, such as the synergetic approach. This book will prove useful to applied mathematicians, physicists, and engineers.







NASA Technical Report


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