Computational Aeroacoustics - Methods and Applications


This course examines the computational issues that are unique to aeroacoustics. Course materials consist of three parts: (a) Introduction; (b) CAA Methods; and (c) Applications. The purpose of the introduction is to provide a brief review of the field of aeroacoustics, including current issues and problem areas (10% of the course). CAA methods form the main component of the course (70%). A number of applications are discussed to illustrate how CAA methods are used in realistic and practical problems (20%). CAA problems are, by definition, time dependent and usually contain high frequency components. Because of the nature of sound one would like to be able to compute CAA problems with as few number of mesh points per wavelength as possible. These characteristics of CAA problems are very different from fluid flow problems. Thus specially developed CAA methods are needed. The students are introduced to these methods.

Key Topics:

  • Computational issues unique to aeroacoustics
  • Optimized dispersion-relation-preserving marching algorithms with minimal numerical dispersion and dissipation
  • Radiation, inflow, outflow and wall numerical boundary conditions
  • Artificial selective damping; choice of damping stencils and mesh Reynolds number
  • Nonlinear wave propagation, shock capturing and multi-scale aeroacoustics problems
  • Examples of applications to aircraft, automobile and flow noise problems
  • Click below for full outline

Who Should Attend:

Acoustic engineers, faculty members, and graduate students interested in aeroacoustics and computational methods should attend this course. This course would also be of great value to those with experience in CFD but who wish to do acoustics and flow noise problems.

Course Information:

Type of Course: Instructor-Led Short Course
Course Length: 2 days
AIAA CEU's available: Yes


1. Introduction

1.1 Sources of aircraft noise
1.2 Computational Issues Relevant to CAA 

2. Spatial Discretization in Wavenumber Space
2.1 Optimized Finite Difference Approximation in Wavenumber Space
2.2 Group Velocity Consideration and Schemes with Large Stencils

3. Time Discretization
3.1 Optimized Multi-Level Time Discretization; Stability Diagram

4. Finite Difference Solution of the Euler Equations
4.1 Dispersion-Relation-Preserving Scheme (DRP scheme)
4.2 Numerical Stability Requirements; choice of time step ; Group Velocity

6. Radiation, Inflow and Outflow Boundary Conditions
6.1 Radiation, Inflow and Outflow Boundary Conditions
6.2 Implementation of Radiation and Outflow Boundary Conditions

7. The Short Wave Component of Finite Difference Schemes
7.1 The Long and the Short Waves; discountinuous initial data 
7.2 Artificial Selective Damping; Excessive Damping; Aliasing

8. Computation of Nonlinear Acoustic Waves
8.1 Nonlinear Simple Waves; Spurious Oscillations: Origin and Characteristics
8.2 Variable Artificial Damping

9. Wall Boundary Conditions for High-Order Finite Difference Schemes
9.1 Concept of Ghost Points and Ghost Values
9.2 Reflection of Acoustic Waves by a Plane Wall; Spurious Boundary Modes

10. Numerical Solution of Multiple-Scales Problems
10.1 Multiple-Scales Aeroacoustics Problems
10.2 Spatial and Time Stencils for Use in Mesh-Size-Change Buffer Region

11. Applications to Real World Problems 





Dr. Christopher Tam is the Robert O. Lawton Distinguished Professor of Mathematics at the Florida State University.  Dr. Tam is a Fellow of the American Institute of Aeronautics and Astronautics (AIAA), a fellow of the American Physical Society (APS), and a fellow of the Acoustical Society of America (ASA).

Dr. Tam has received a number of awards, including:
• AIAA Pendray Aerospace Sciences Literature Award, AIAA, 2006
• NASA TGIR Award (airframe noise), NASA, 2001
• Robert O. Lawton distinguished Professor, Florida State University, 2000
• AEDC Annual Technology Achievement Award, Arnolds Engineering & Development Center, 1993
• AIAA Aeroacoustics Award, AIAA, 1987
• Lockheed Aircraft Company Disclosure of Invention Award, Lockheed, 1981



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