The recombination of two vortex filaments in a viscous incompressible fluid is analyzed by the use of the vorticity equation. The analysis is confined to a local flow field where the recombination process occurs and is based on several assumptions, such as conservation of the fluid impulse, spatial symmetry of the flow field, etc. The flow field is expanded as polynomials of coordinates, and variations of their coefficients are obtained by the use of the vorticity equation. The result is applied to predict the far-field noise of a circular jet by assuming that the main noise source is the recombination process in deformed vortex rings in the jet near field. The predicted noise intensity shows the U**8 dependence and has an additional new factor (d/ sigma )**6; U is the jet velocity and d is the average spacing between vortex rings. The predicted intensity distribution is directional even without the effect of source convection.
|Pages||3. 19-3. 25|
|State||Published - 1985|