Spring 2022
Prof. Aniruddha Sinha
Author: M Vishnu Sankar
Pre-requisite courses: Fluid Dynamics
Pre-requisite skills: Python/MATLAB programming
Course Content: Preliminaries:
- Introduction
- Fourier (spectral) analysis of (acoustic) signals Propagation of sound waves:
- 1-D acoustics in a medium at rest
- 3-D acoustics in a general base flow
- Elements of solutions of Helmholtz equation
- Acoustic fluctuations in non-uniform media (sheared flows) Computational aeroacoustics:
- Spatial discretization of governing equations in wavenumber space
- Time discretization
- Finite difference solutions of linearized Euler equation, and implementation of boundary conditions Aeroacoustic sources and their sound fields:
- Sources of aeroacoustic sound and their resultant fields
- Sound field of oscillating spheres (as elemental sources)
- Introduction to generalized functions
- Green’s theory for solution of partial differential equations, as required in acoustics
- Sound field due to monopole, dipole and quadrupole sources, their importance, and their relation to oscillating spheres
- Analysis of sound due to moving sources
- Reciprocal theorem in linear acoustics
- Kirchhoff’s formula of linear acoustics in the presence of surfaces
- Lighthill’s theory, and application to jet noise
- Ffowcs-Williams and Hawkings’ formulation of nonlinear acoustics in the presence of surfaces
- Scattering of sound at an edge, as applicable to airfoil noise
- Study of current literature on various topics of aeroacoustics
Motivation to take up the course: I love Sinha Sir’s teaching and any topic related to fluid mechanics
Course Evaluation Structure:
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10%: Weekly 5-min. quiz (10x1%)
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10%: 30-minute quiz (2x5%)
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50%: Homework assignments (4 assignments, 10%, 10%, 20%, 10%) (2 computational assignments and 2 problem solving type assignments. Assignments are not straight forward, start solving them well before the deadline to finish them on time)
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10%: Literature study report and presentation
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20%: Final exam (comprehensive)
Quizzes/Midsem/Endsem papers Difficulty: 4/5
Projects/Assignments Difficulty: 5/5
General funda: This is not a course which you can study a few days before the exam and get along with it. If you flunk the classes be prepared to flunk the exams as well
Professor’s Teaching Style: Sinha sir’s lectures are amazing, the beautiful mathematical essence and physical intuitions are never missing in his lectures.
Should you do this course?: Anyone interested in understanding the practical and theoretical understanding of Aeroaoustics (computational aspect of it especially) can take this course. It is definitely one of the most ‘hot’ research topics out there. Has a lot of potential applications on Urban Air Mobility vehicles and supersonic flight travel.
References:
- Goldstein, M. E., Aeroacoustics, McGraw-Hill, 1976
- C. K. W. Tam. Computational Aeroacoustics: A Wave Number Approach. Cambridge Univ Press, 2012