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CAA:
The Computational Aeroacoustics (CAA) module in ASTE-P is used for prediction of the far-field sound generated by turbulent flows often of interest to the aerospace industry. This module can also help understand the near-field acoustic source terms which can lead to suppression/control of the acoustic sources to reduce noise emissions. The solver is based on structured grid. High-order numerics and accurate boundary conditions are specified to minimize dissipation and dispersion errors. Hybrid approach is considered in our CAA module for noise prediction. In this approach, the near-field source terms are computed using Direct Numerical Simulations (DNS)/Large Eddy Simulations (LES). The source terms are used as input to the acoustic models to predict far-field sound. Hybrid approaches are highly efficient and can accurately predict the far-field sound. Most commercial softwares are second-order accurate at the most which is not suitable for aeroacoustics. Our CAA module is based on sixth-order Compact Schemes and fifth-order WENO schemes which are suitable for noise predictions. The main features of CAA module include:

LES simulation of Jet Impingement

Near-field Vorticity Magnitude and Far-field Sound (Shown using Dilatation Contours) for Free Jet using Our LES Code
Isosurface of Vorticity Magnitude Colored with Axial Velocity for Subsonic Free Jet using LES
¡ñ Three different acoustic models are available viz. (i) Linearized Euler Equations (LEE), (ii) Acoustic Intensity Based Method (AIBM), and (iii) Ffocws Williams-Hawkings (FWH) equation (implementation underway and to be released in later version)
¡ñ Sixth-order compact schemes and fifth-order WENO scheme for spatial discretization and fifth-order Runge-Kutta method for temporal integration are employed
¡ñ Characteristic-based, non-reflecting boundary conditions are specified to minimize reflections from inflow and outflow boundaries
¡ñ A high-order implicit filter is used to remove saw-tooth-like numerical oscillations.
¡ñ FWH has been widely used in the past for free jet noise predictions
¡ñ AIBM is a relatively new model, however, has been found to be as accurate as FWH but lot more efficient
¡ñ LEE is computationally expensive as it includes both the near-field and far-field sound into the computational domain. However, LEE can be used to predict far-field sound in presence of strong convection and refraction effects. LEE can also be used to study the near-field acoustic source terms
¡ñ CAA module also has the capability to predict far-field sound using DNS/LES instead of the above three hybrid approaches
¡ñ Both 2D and 3D simulations can be run using this module
¡ñ Multiblock approach using overlapping grids is used for complex geometries. The multiblock approach also improves the efficiency of the solver

Far-field Sound Spectra using the AIBM Hybrid Approach (Dashed Line) of our CAA Module Compared with LES (Solid Line) Results for Validation

 
Headquarters: Advanced Dynamics Inc. 1500 Bull Lea Road, Suite 203, Lexington, KY 40511
For immediate inquiries call Tel: (859) 699-0441 Fax:(859) 243-5615 Email: Contact@advanceddynamics-usa.com
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