Lilley Sources Model Reference

The Lilley Sources model uses a nonlinear function to compute the turbulent shear flow noise of quadropole sources from a synthetic turbulent velocity field.

Note	This model only solves for noise sources—not for acoustic wave propagation.

Table 1. Lilley Sources Model Reference
Theory	See Lilley Noise Source Model.
Provided By	[physics continuum] > Models > Broadband Noise Source Models
Example Node Path	Continua > Physics 1 > Models > Lilley Sources
Requires	Space: Two Dimensional, Three Dimensional, or Axisymmetric Time: Steady Material: any but solid Flow: any Viscous Regime: Turbulent Turbulence: Reynolds-Averaged Navier-Stokes Reynolds-Averaged Turbulence: any Optional Models: Aeroacoustics Aeroacoustics Models: Broadband Noise Sources
Properties	Key properties are: Number of Realizations Number of Fourier Modes See Lilley Sources Model Properties.
Activates	Solvers	Lilley Source Solver See Lilley Source Solver.
	Field Functions	Lilley Self Noise Source Lilley Shear Noise Source Lilley Total Noise Source See Field Functions.

Lilley Sources Model Properties

Number of Realizations: The number of samples used to compute the average of the synthetic turbulent velocity field based on the Stochastic Noise Generation and Radiation (SNGR) approach.; The default value is 200. You can use up to 1000 realizations (see Karweit et al. [66]).; Increasing the number of realizations increases computational costs.
Number of Fourier Modes: The number of the Fourier modes $n$ used for the spectral resolution for isotropic turbulence given by a von Karman-Pao spectrum, when computing the synthetic turbulent velocity field, see Eqn. (4698)).; The default value is 50. Use values between 30 and 50 Fourier modes.; Increasing the number of Fourier modes increases computational costs.

Lilley Source Solver

The Lilley Source solver controls the iterative update for the noise source calculations. First, the Lilley Source solver calls the Stochastic Noise Generation and Radiation (SNGR) solver, then computes the Lilley noise source terms. The SNGR solver computes the synthetic turbulent velocity field and gradients of that field using the SNGR method.

The following right-click action is available:

Execute solver: Calculates the values for the Lilley Sources field functions. To stop the solver immediately, without completing the set number of realization steps, click on the solver stop button located next to the progress bar. The solver stops and saves the partially computed field functions.

Field Functions

Lilley Self Noise Source: The Lilley source term that computes the sound generated by turbulent velocity components, see $S_{S e l f N o i s e T e r m}$ given by Eqn. (4690).
Lilley Shear Noise Source: The source term that computes the acoustic effects from the interaction between the mean shear flow and turbulent velocity components, see $S_{S h e a r N o i s e T e r m}$ given by Eqn. (4691).
Lilley Total Noise Source: The sum of the Lilley Self Noise Source and Lilley Shear Noise Source.