Ebook: Computational Aeroacoustics

Computational aeroacoustics is rapidly emerging as an essential element in the study of aerodynamic sound. As with all emerging technologies, it is paramount that we assess the various opportuni­ ties and establish achievable goals for this new technology. Essential to this process is the identification and prioritization of fundamental aeroacoustics problems which are amenable to direct numerical siIn­ ulation. Questions, ranging from the role numerical methods play in the classical theoretical approaches to aeroacoustics, to the correct specification of well-posed numerical problems, need to be answered. These issues provided the impetus for the Workshop on Computa­ tional Aeroacoustics sponsored by ICASE and the Acoustics Division of NASA LaRC on April 6-9, 1992. The participants of the Work­ shop were leading aeroacousticians, computational fluid dynamicists and applied mathematicians. The Workshop started with the open­ ing remarks by M. Y. Hussaini and the welcome address by Kristin Hessenius who introduced the keynote speaker, Sir James Lighthill. The keynote address set the stage for the Workshop. It was both an authoritative and up-to-date discussion of the state-of-the-art in aeroacoustics. The presentations at the Workshop were divided into five sessions - i) Classical Theoretical Approaches (William Zorumski, Chairman), ii) Mathematical Aspects of Acoustics (Rodolfo Rosales, Chairman), iii) Validation Methodology (Allan Pierce, Chairman), iv) Direct Numerical Simulation (Michael Myers, Chairman), and v) Unsteady Compressible Flow Computa­ tional Methods (Douglas Dwoyer, Chairman).

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The general topic is the generation of sound by, and the propagation of sound in fluid flows. These include flows around machinery, airfoils, and other man-made objects, as well as the flow of wind around obstacles. The chapters in this volume represent the results of a workshop discussing mathematical and computational aspects of the interaction of sound with air at the Institute for Computer Applications in Science and Engineering, at the NASA Langley Research Center. Topics covered include: classical theoretical approaches (which can serve to supply both efficient formulations for computational implementation and the boundary conditions that are essential for accurate simulations); mathematical aspects of acoustics; validation methods (including stability considerations, gridding, and back-reactions); direct simulation (the use of computational fluid dynamics to describe the generation, transmission, and radiation of sound in fluid flows); and computational methods for unsteady compressional flows. The topics covered in this book will be of interest to aerospace and other mechanical engineers interested in modeling and reducing noise generated by fluid flows such as propeller noise from windmills, sonic booms due to aircraft, or buildings that sing in the wind.

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The general topic is the generation of sound by, and the propagation of sound in fluid flows. These include flows around machinery, airfoils, and other man-made objects, as well as the flow of wind around obstacles. The chapters in this volume represent the results of a workshop discussing mathematical and computational aspects of the interaction of sound with air at the Institute for Computer Applications in Science and Engineering, at the NASA Langley Research Center. Topics covered include: classical theoretical approaches (which can serve to supply both efficient formulations for computational implementation and the boundary conditions that are essential for accurate simulations); mathematical aspects of acoustics; validation methods (including stability considerations, gridding, and back-reactions); direct simulation (the use of computational fluid dynamics to describe the generation, transmission, and radiation of sound in fluid flows); and computational methods for unsteady compressional flows. The topics covered in this book will be of interest to aerospace and other mechanical engineers interested in modeling and reducing noise generated by fluid flows such as propeller noise from windmills, sonic booms due to aircraft, or buildings that sing in the wind.
Content:
Front Matter....Pages i-xxi
Front Matter....Pages 1-1
A General Introduction to Aeroacoustics and Atmospheric Sound....Pages 3-38
Front Matter....Pages 39-39
Classical Theoretical Approaches to Computational Aeroacoustics....Pages 41-49
Computational Aeroacoustics for Low Mach Number Flows....Pages 50-68
A Multiple Scales Approach to Sound Generation by Vibrating Bodies....Pages 69-84
On the Noise Radiated from a Turbulent High Speed Jet....Pages 85-115
A Study of the Short Wave Components in Computational Acoustics....Pages 116-130
Front Matter....Pages 131-131
The Acoustic Analogy as a Tool of Computational Aeroacoustics....Pages 133-155
Problems with Different Time Scales and Acoustics....Pages 156-166
Front Matter....Pages 167-167
Validation Methodology: Review and Comments....Pages 169-173
Wall Pressure and Radiated Noise Generated by 3 Line Vortices in Chaotic Motion Close to a Solid Surface....Pages 174-189
Acoustic Scattering by an Elastic Window in a Rigid Duct: Numerical Approaches....Pages 190-205
Calculation of Noise Produced by High Mach Number Jets....Pages 206-215
Regarding Numerical Considerations for Computational Aeroacoustics....Pages 216-228
Observed and Computed Waves of Aerodynamic Sound....Pages 229-244
Validation of Computational Aeroacoustics Algorithms....Pages 245-259
Model Problems Associated with the Prediction of Noise by High Speed Shear Layers....Pages 260-281
Front Matter....Pages 283-283
Direct Simulation: Review and Comments....Pages 285-293
Time-Dependent Jet Noise Computation Techniques....Pages 294-306
A Consideration of Energy from the Viewpoint of Computational Aeroacoustics....Pages 307-324
Direct Computation of Aerodynamic Noise....Pages 325-334
Front Matter....Pages 283-283
Computation of the Acoustic Radiation from Bounded Homogeneous Flows....Pages 335-355
On the Development of a Time Domain Method for Caa “The Successes and Failures”....Pages 356-370
Front Matter....Pages 371-371
CFD Methods Development Considerations for Unsteady Aerodynamic Analysis....Pages 373-403
Numerical Study of Flow/Structure Interaction over a Flexible Plate....Pages 404-416
Navier-Stokes Simulations of Blade-Vortex Interaction Using High-Order-Accurate Upwind Schemes....Pages 417-430
Front Matter....Pages 431-431
Scattering of Sound by Rigid Bodies in Arbitrary Flows....Pages 433-455
Application of Geometrical Acoustics to Propagation of High Frequency Jet Noise....Pages 456-480
Application of a CFD Code for Unsteady Transonic Aerodynamics to Problems in Aeroacoustics....Pages 481-495
Front Matter....Pages 497-497
The Final Panel Discussion....Pages 499-513

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The general topic is the generation of sound by, and the propagation of sound in fluid flows. These include flows around machinery, airfoils, and other man-made objects, as well as the flow of wind around obstacles. The chapters in this volume represent the results of a workshop discussing mathematical and computational aspects of the interaction of sound with air at the Institute for Computer Applications in Science and Engineering, at the NASA Langley Research Center. Topics covered include: classical theoretical approaches (which can serve to supply both efficient formulations for computational implementation and the boundary conditions that are essential for accurate simulations); mathematical aspects of acoustics; validation methods (including stability considerations, gridding, and back-reactions); direct simulation (the use of computational fluid dynamics to describe the generation, transmission, and radiation of sound in fluid flows); and computational methods for unsteady compressional flows. The topics covered in this book will be of interest to aerospace and other mechanical engineers interested in modeling and reducing noise generated by fluid flows such as propeller noise from windmills, sonic booms due to aircraft, or buildings that sing in the wind.
Content:
Front Matter....Pages i-xxi
Front Matter....Pages 1-1
A General Introduction to Aeroacoustics and Atmospheric Sound....Pages 3-38
Front Matter....Pages 39-39
Classical Theoretical Approaches to Computational Aeroacoustics....Pages 41-49
Computational Aeroacoustics for Low Mach Number Flows....Pages 50-68
A Multiple Scales Approach to Sound Generation by Vibrating Bodies....Pages 69-84
On the Noise Radiated from a Turbulent High Speed Jet....Pages 85-115
A Study of the Short Wave Components in Computational Acoustics....Pages 116-130
Front Matter....Pages 131-131
The Acoustic Analogy as a Tool of Computational Aeroacoustics....Pages 133-155
Problems with Different Time Scales and Acoustics....Pages 156-166
Front Matter....Pages 167-167
Validation Methodology: Review and Comments....Pages 169-173
Wall Pressure and Radiated Noise Generated by 3 Line Vortices in Chaotic Motion Close to a Solid Surface....Pages 174-189
Acoustic Scattering by an Elastic Window in a Rigid Duct: Numerical Approaches....Pages 190-205
Calculation of Noise Produced by High Mach Number Jets....Pages 206-215
Regarding Numerical Considerations for Computational Aeroacoustics....Pages 216-228
Observed and Computed Waves of Aerodynamic Sound....Pages 229-244
Validation of Computational Aeroacoustics Algorithms....Pages 245-259
Model Problems Associated with the Prediction of Noise by High Speed Shear Layers....Pages 260-281
Front Matter....Pages 283-283
Direct Simulation: Review and Comments....Pages 285-293
Time-Dependent Jet Noise Computation Techniques....Pages 294-306
A Consideration of Energy from the Viewpoint of Computational Aeroacoustics....Pages 307-324
Direct Computation of Aerodynamic Noise....Pages 325-334
Front Matter....Pages 283-283
Computation of the Acoustic Radiation from Bounded Homogeneous Flows....Pages 335-355
On the Development of a Time Domain Method for Caa “The Successes and Failures”....Pages 356-370
Front Matter....Pages 371-371
CFD Methods Development Considerations for Unsteady Aerodynamic Analysis....Pages 373-403
Numerical Study of Flow/Structure Interaction over a Flexible Plate....Pages 404-416
Navier-Stokes Simulations of Blade-Vortex Interaction Using High-Order-Accurate Upwind Schemes....Pages 417-430
Front Matter....Pages 431-431
Scattering of Sound by Rigid Bodies in Arbitrary Flows....Pages 433-455
Application of Geometrical Acoustics to Propagation of High Frequency Jet Noise....Pages 456-480
Application of a CFD Code for Unsteady Transonic Aerodynamics to Problems in Aeroacoustics....Pages 481-495
Front Matter....Pages 497-497
The Final Panel Discussion....Pages 499-513
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