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numerical OUTFLOW BOUNDARY-CONDITION FOR NAVIER-STOKES FLOW CALCULATIONS BY A LINE ITERATIVE METHOD

AIAA JOURNAL 1985年第12期23卷 1847-1848页

作者： SHYY, W General Electric Research and Development Center Schenectady New York

This study investigates the use of explicit/implicit, step/linear space extrapolation as numerical outflow boundary conditions for turbulent flow calculations. The emphasis is on the interplay between the use of curvilinear coordinate systems for complex flow calculation and the semiimplicit line iterative procedure. Both a planar singlechanneled and an annular multichanneled flow configuration were used as test models. It was found that implicit linear space extrapolation needs more computing time and may not yield a unique solution. On the other hand, explicit zero-order space extrapolation appears to be a robust outflow boundary condition since it has the largest stability limit with respect to underrelaxation factors and initial conditions. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Computing Time Turbulent Flow Curvilinear Coordinates Turbulence Kinetic Energy numerical algorithms Mass Flux Navier Stokes Equations Gas Turbine Combustor Flow Characteristics Fluid Mechanics

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A MAPPED, FACTORED-IMPLICIT SCHEME FOR THE COMPUTATION OF DUCT AND FAR-FIELD ACOUSTICS

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AIAA JOURNAL 1985年第4期23卷 629-631页

作者： WHITE, JW RAAD, PE The University of Tennessee Knoxville Tennessee

A new time-dependent, finite difference scheme is developed with several specific objectives in mind. First, accurate implementation of the boundary conditions is very important due to the reflective nature of the hyperbolic equations governing noise propagation. Thus, one objective of the method is that the numerical solution should be developed around a general mapping procedure. A number of different approaches to numerical mapping may be found in the literature.

关键词： Acoustics Acoustic Propagation Finite Difference Method Velocity Profiles Shear Layers NASA Lewis Research Center numerical algorithms Radiation Pattern Transient Response Computer Memory

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PREDICTION OF SECONDARY VORTEX FLOWFIELDS GENERATED BY AN INTERACTING MULTIPLE FREE-JET CONFIGURATION

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AIAA JOURNAL 1985年第7期23卷 983-984页

作者： BAKER, AJ ORZECHOWSKI, JA STUNGIS, GE COMPUTAT MECH CONSULTANTS INC KNOXVILLETN BROWN & WILLIAMSON TOBACCO CORP LOUISVILLEKY

A PENALTY finite element algorithm for solution of the three-dimensional parabolic Navier-Stokes equations for subsonic turbulent flows is applied to the prediction of secondary vortex flowfields induced by a multiple free-jet configuration. The combined action of rapid decay of the initial high-speed parallel jets, turbulence level, induced entrainment from the far field, and geometric discreteness of a four-jet configuration, is predicted to produce a persistent system of eight counterrotating vortex pairs in the plane normal to the initial jet axis. numerical predictions are interpreted and compared with available experimental data. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Vortex Structure Subsonic Turbulent Flow Navier Stokes Equations Smoke Flow Visualization Continuity Equation Poisson's Equation numerical algorithms Solution Algorithm Computer Programs Streamtube

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A PERSPECTIVE OF THEORETICAL AND APPLIED COMPUTATIONAL FLUID-DYNAMICS

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AIAA JOURNAL 1985年第3期23卷 328-341页

作者： KUTLER, P NASA Ames Research Center Moffett Field California

This paper discusses the advantages and disadvantages that underlie the growth of computational fluid dynamics (CFD) and its increasing role in the design of new flight vehicles. CFD tools are important because they reduce the amount of experimental development work from what would have been required without their use. There are both primary and secondary pacing items that must and are being addressed by the CFD research community. They include (1) three-dimensional grid generation, (2) turbulence modeling, (3) algorithm development, and (4) computer mainframe design advances. The secondary pacing items include (1) algorithm development, (2) complex geometry definition, and (3) input and output data processing. Most of this paper is devoted to a discussion of these pacing items. In addition, user demands on computational tools for simulations are also discussed.

关键词： Applied Computational Fluid Dynamics Software Development Ames Research Center Aerospace Engineering Reynolds Averaged Navier Stokes Aerodynamic Flowfield Scientific Computing Navier Stokes Solver Turbulence Models numerical algorithms

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IMPACT OF COMPUTATIONAL FLUID-DYNAMICS ON DEVELOPMENT TEST FACILITIES

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JOURNAL OF AIRCRAFT 1985年第3期22卷 182-187页

作者： KORKEGI, RH National Research Council Washington D. C.

The impact of computational fluid dynamics (CFD) on the traditional role of aeronautical ground test facilities over the next 15 years is assessed via a National Research Council study. More powerful scientific computers and more efficient numerical algorithms should result in the ability to practically compute the flowfield about a complete aircraft with the Reynolds-averaged Navier-Stokes equations at a unit cost three orders of magnitude lower than at present. No dramatic change in the cost of testing in ground facilities is foreseen because more efficient computer-enhanced facility operation is partially offset by increased power and labor costs. From the user viewpoint, the risk in development of a new aircraft or engine is so great that use of proven methods of verification by means of test facilities will not change significantly. In the next 15 years CFD and ground test facilities will be utilized in a complementary rather than competitive mode of obtaining design data and the end result will be a better product. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： CFD Transonic Wind Tunnel Reynolds Averaged Navier Stokes Aircraft Configurations Turbulence Models numerical algorithms Aeronautics Aircraft Engine Design Angle of Attack Supercomputers

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LOW-VELOCITY IMPACT RESPONSE OF LAMINATED BEAMS SUBJECTED TO INITIAL STRESSES

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AIAA JOURNAL 1985年第12期23卷 1962-1969页

作者： SANKAR, BV SUN, CT PURDUE UNIV AERONAUT & ASTRONAUTW LAFAYETTEIN 47907

Finite element procedures are used in conjunction with a numerical algorithm to compute the impact response of a graphite-epoxy laminated beam subjected to tensile initial stresses. The effect of initial stresses on the contact duration, impact force, coefficient of restitution, and bending and shear stresses are discussed. The analytically computed contact force history and strain response are compared with some experimental results. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Maximum Shear Stresses numerical algorithms Finite Element Modeling Linear Elasticity Energy Transfer Plastic Deformation Composite Laminates Material Properties Pneumatic Cylinders Green's Function

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PERTURBATIONS OF A TRANSONIC FLOW WITH VANISHING SHOCK-WAVES

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AIAA JOURNAL 1985年第6期23卷 965-967页

作者： NIXON, D KERLICK, GD Nielsen Engineering and Research Inc. Mountain View California

The computation of transonic flows using potential theory is fairly commonplace, although the computation cost is still high and, consequently, considerable effort has been expended in trying to reduce the total costs of the necessary calculations. One approach toward cost reduction is the development of the transonic perturbation theory. This note presents an investigation into the behavior of the transonic perturbation theory when shock waves vanish. It is shown that, when shock waves vanish, a piecewise application of the perturbation theory is necessary at that point since the equation set is discontinuous there. It is also shown that the range of transonic solutions can be constructed if the incompressible solutions and one transonic solution are known.

关键词： Mach Angle Incompressible Flow Perturbation Method Freestream Mach Number NACA 64A006 Turbulent Boundary Layer Angle of Attack numerical algorithms Temperature Ratio Wall Temperature

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CONTROLLABILITY AND OBSERVABILITY OF GENERAL LINEAR LUMPED-PARAMETER SYSTEMS

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1985年第5期8卷 669-672页

作者： AHMADIAN, M Clemson University Clemson South Carolina

The representation of the dynamic behavior of a general linear discrete system by a second-order vector differential equation is considered along with the mathematical definition of the controllability and observability of a system. Although the rank conditions involved are conceptually simple, computational difficulties may arise for systems with many degrees of freedom. In an effort to develop more efficient conditions, Hughes and Skelton (1980) have used a decoupled form of the original equation, while Juang and Balas (1980) have considered conservative gyroscopic systems. Inman and Hsieh (1983) have discussed the active control of pseudoconservative systems. The main objective of the present investigation is related to an extension of the results on controllability and observability conditions proposed in the three earlier studies. The extension is to make applications to a broader class of systems possible. The model of a lumped-parameter system with general types of forces is considered.

关键词： Radomes Kalman Filter Gain Influence Coefficients Guidance Computer Active Control Autopilot Proportional Navigation Lumped Parameter Model Large Space Structures numerical algorithms

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ASYMPTOTIC ANALYSIS OF THICK AXISYMMETRIC TURBULENT BOUNDARY-LAYERS

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AIAA JOURNAL 1985年第6期23卷 963-965页

作者： AFZAL, N NARASIMHA, R ALIGARH MUSLIM UNIV DEPT AEROSP ENGNALIGARH 202001UTTAR PRADESHINDIA

The similarity laws governing the axisymmetric turbulent boundary layer have been the subject of prolonged debate. Herein constant pressure flow at velocity U past a circular cylinder of radius a with the axis aligned to the flow is considered. The asymptotic analysis shows that the inner and outer velocity distributions have functional dependences. The extended asymptotic theory permits a dependence of both the Karman parameter A and the outer intercept D on a// plus . The implied dependence of the outer flow on the viscosity (through a// plus ) may raise questions about whether the flow still can be characterized as fully turbulent.

关键词： Turbulent Boundary Layer Kinematic Viscosity Perturbation Theory Two Dimensional Flow Transonic Aerodynamics numerical algorithms

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CONSERVATION FORM OF THE EQUATIONS OF FLUID-DYNAMICS IN GENERAL NONSTEADY COORDINATES

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AIAA JOURNAL 1985年第11期23卷 1819-1820页

作者： ZHANG, H CAMARERO, R KAHAWITA, R ECOLE POLYTECH DEPT APPL MATHMONTREAL H3C 3A7QUEBECCANADA

A more direct method than has been reported previously to derive the conservative form of the equations of fluid dynamics in general nonsteady curvilinear coordinates has been presented. The geometric conservation law... 详细信息

关键词： Conservation Equations Navier Stokes Equations Finite Volume Method Gas Dynamics Finite Difference Approximation Compressibility Effect numerical algorithms Incompressible Flow

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