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Related Experiment Video

Updated: Jul 13, 2026

Preparation of Free-Surface Hyperbolic Water Vortices

Preparation of Free-Surface Hyperbolic Water Vortices

Published on: July 28, 2023

Vorticity dynamics and sound generation in two-dimensional fluid flow.

Raymond J Nagem¹, Guido Sandri, David Uminsky

¹Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA. nagem@bu.edu

The Journal of the Acoustical Society of America

|July 7, 2007

Summary

This study introduces a new method using vorticity expansion to analyze fluid motion and predict sound generation. The approach accurately models vortex pairs and their acoustic pressure, outperforming prior theoretical predictions.

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Area of Science:

Fluid Dynamics
Acoustics
Computational Physics

Background:

Incompressible fluid equations govern fluid motion.
Vorticity describes fluid rotation and is key to understanding complex flows.
Predicting sound generated by fluid dynamics is crucial in many engineering applications.

Purpose of the Study:

To develop an approximate analytical solution for two-dimensional incompressible fluid equations.
To analyze the motion and acoustic properties of corotating Gaussian vortex pairs.
To establish a novel method for predicting sound from distributed vorticity fields.

Main Methods:

Expanding the vorticity field using derivatives of a Gaussian vortex.
Deriving spatial rotation frequency directly from the fluid vorticity equation.
Applying the expansion to the low Mach number Lighthill equation for acoustic pressure prediction.

Main Results:

The derived rotation frequency accounts for finite vortex core size and viscosity.
The method accurately predicts far-field acoustic pressure for Gaussian vortex pairs.
The analytical results show superior accuracy compared to previous numerical simulations and theoretical predictions.

Conclusions:

Vorticity expansion is an effective tool for analyzing fluid dynamics and acoustics.
This method offers a more accurate approach to predicting sound generated by distributed vorticity.
The findings advance the understanding of vortex dynamics and aeroacoustics.