Lecture 1 Notes: Computational Acoustics
First off, welcome. I hope that these notes are interesting and helpful to you.
Also, please note that there is a set of Comments on each lecture, that go along with the
readings and the Instructors Notes here.
Let
Lecture 2 Notes: Velocity Potential
A. Observables, Scalar Potentials (for compressional waves)
We want to solve a full wave equation soon, and pressure, particle displacement,
and particle velocity are all observables we can solve for. We will see that t
Lecture 10 Notes: Central Techniques
In this final lecture, we look at Bayesian and nonlinear inverses. Sadly, due to lack of time, we
skipped the material on older, basic nonlinear methods in Chapters 9 and 10 in ABT, and went straight
to Bayesian method
Lecture 6 Notes: Finite Difference
A. Simple finite difference method for solving the mode eigenvalue problem
Rather than using the sound speed, let us define an equally useful quantity, the
slowness by
S(z)1 c(z)
In terms of slowness, our DE for the acou
Lecture 5 Notes: Corresponding Nodes
A. Rays as interfering modes
The traditional picture of modes is that of constructively interfering plane waves at
angles . We will show here that rays can be represented as constructively
interfering groups of neighbo
Lecture 4 Notes: Virtual Modes
Dealing with the Continuum Virtual Modes:
When sound energy reflects off the seabed, a portion of it past critical angle is lost by
transmission to infinity. The same is true to a lesser extent for the sea surface (which is
Lecture 3 Notes: Receiver Depth
Here, r/1,so that I=0. Due to diffraction, Iis not zero in this shadow zone region,
so this is another ray theory pathology.
We would note that caustics and shadow zones generally go together. If on focuses
light/sound in o
Lecture 7 Notes: Derivation of PE
A. Derivation of basic PE
Lets look at a very clever and popular way to solve the acoustic wave equation, called
the parabolic equation (PE) method. This is an old method now (transcribed for
underwater acoustics from Rus
Lecture 8 Notes: Lobe Equation
Some simple beamformer equations
Again, at this level, the simple concepts of beamforming should be well known, but at the risk of a little
triviality (never a great risk.people are good at skipping over material they alread
Lecture 9 Notes: Spatial Entitys
The ocean water column is very much a 3-D spatial entity, and we need to
represent that structure in an economical way to deal with it in calculations. We
will discuss one way to do so, empirical orthogonal functions, in w