Simulation of Sound Propagation in Boundary Layers Based on Möhring's Acoustic Analogy

16th AIAA/CEAS Aeroacoustics Conference

Ewert

2010

A promising way to predict airframe noise is the numerical solution of the Acoustic Perturbation Equations (APE) with the help of the Discontinuous Galerkin Method (DGM) and the Fast Random Particle Mesh (FRPM) method. The latter stochastically computes the turbulent source term of the APE, while the DGM reliably provides their spatial discretization, even on a flexible unstructured grid. The goal of the current work is to compute broadband slat noise of two different high-lift airfoil configurations in two dimensions with this approach. The dependency of the result on the resolution of both the FRPM-as well as the DG-grid is analysed, and the parameter sensitivity of the FRPM method is investigated. Furthermore, computed sound pressure spectra are compared to measured spectra, and computational times are examined.

Section: Introductionmentioning

confidence: 96%

Slat Noise Prediction Using Discontinuous Galerkin Method and Stochastic Turbulent Sound Source

16th AIAA/CEAS Aeroacoustics Conference

Ewert

2010

“…(2) are expanded in the fashion of Eq. (11). This includes the components U r , r ∈ {1, 2, 3}, of the vector of unknowns U = [p ′ , u ′ , v ′ ] T , as well as the components F x r , F y r , and S r of the flux vectors and of the source vector, respectively.…”

Section: Iic2 Approximate Representation Of Field Variablesmentioning

confidence: 99%

“…(5), are also approximated according to Eq. (11). Thus, they are also represented by polynomials of degree p = 3.…”

Section: Iic2 Approximate Representation Of Field Variablesmentioning

confidence: 99%

“…(4), the approximate flux quantitiesF x r ,F y r are products of mean and perturbation quantities, and are thus actually polynomials of degree 2p. But, in order to save computational effort, they are truncated to degree p, which is very easy through the Lagrangian nodes, 11,28,29 and are also approximated in the fashion of Eq. (11).…”

Section: Iic2 Approximate Representation Of Field Variablesmentioning

confidence: 99%

“…On such grids, it realizes the APE's spatial discretization through a DGM, which is based on nodal basis functions given in terms of Lagrange polynomials. 11,28,29 Time integration is performed by means of the standard, explicit, multi-stage Runge-Kutta scheme of order four (RK4). In Refs.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the performance of airframe noise prediction on unstructured grids

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

Dierke

Ewert

2012

Airframe noise of complex geometries may conveniently be computed on unstructured grids, which can be generated automatically and quickly. The particular goal of this work is to predict broadband airframe noise of a specific three-element high-lift airfoil configuration on such a grid. Therefore, a discontinuous Galerkin (DG) method provides the spatial discretization of the acoustic perturbation equations, whose turbulent source term is modelled efficiently via the fast random particle-mesh method based on RANS data. Time integration is carried out by means of the standard, explicit Runge-Kutta scheme of order four (RK4). In two space dimensions, the DG computation on an unstructured triangular grid turned out to be as efficient as a finite difference-based simulation on a sophisticated block-structured grid. Local time stepping significantly increases the performance of the RK4-DG simulation even further. Nevertheless, acoustic results agree well with elaborate scale-resolving approaches.

Computation of Trailing Edge Noise with a Discontinuous Galerkin Method

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

2010

Trailing edge noise of a semi-infinite, thin, flat plate situated in low Mach number flow is computed in two spatial dimensions. The Acoustic Perturbation Equations (APE), which are employed as governing equations, are discretized via a Discontinuous Galerkin Method (DGM). Results are compared with theory and Finite Difference (FD) computations. Next to the radiated sound field, special attention is paid to the conditions very close to the trailing edge (TE).