A unique concept of utilizing localized surface compliance is proposed to suppress deep cavity aeroacoustics at a low Mach number. The core idea provide local absorption the energy aeroacoustic processes supporting flow self-sustained feedback loop responsible for tonal noise generation. studied with past length-to-depth ratio 0.4 freestream number 0.09 and Reynolds based on length 4 × 104 usin...

In regard to the problem of aircraft noise mitigation, the present study focuses on the refraction effects to be possibly induced by anechoic facility jet flows on the measured acoustic signatures, during typical airframe noise experiments. To this end, Computational AeroAcoustics (CAA) calculations based on the solving of the Perturbed Euler Equations (PEE) are conducted, enabling the estimati...

Consider inviscid ‡uids in a channel f 1 < y < 1g. For the Couette ‡ow ~v0 = (y; 0), the vertical velocity of solutions to the linearized Euler equation at ~v0 decays in time. At the nonlinear level, such inviscid damping is widely open. First, we show that in any (vorticity) H s < 3 2 neighborhood of Couette ‡ow, there exist non-parallel steady ‡ows with arbitrary minimal horizontal period. Th...

Considered here are Boussinesq systems of equations of surface water wave theory over a variable bottom. A simplified such Boussinesq system is derived and solved numerically by the standard Galerkin-finite element method. We study by numerical means the generation of tsunami waves due to bottom deformation and we compare the results with analytical solutions of the linearized Euler equations. ...

*Central Aerohydrodynamic Institute (TsAGI) Zhukovsky street, 1, 140185 Zhukovsky, Moscow Region, Russian Federation, Email: [email protected] **Central Aerohydrodynamic Institute (TsAGI) Zhukovsky street, 1, 140185 Zhukovsky, Moscow Region, Russian Federation, Email: [email protected] ***NUMECA International, Avenue Franklin Roosevelt, 5, 1050 Brussels, Belgium, Email: charles.hirsch@num...

The aim of this work is to accurately and efficiently predict sound radiation out of a duct with flow. The sound propagation inside a generic engine bypass duct, refractions by the shear layer of the exhaust flow, and propagation in the near field are the main focus of the study. The prediction uses either a modified form of linearized Euler equations or an alternative model based on acoustic p...

We investigate problems of fluid structure interaction type and aim for a formulation that leads to a well posed problem and a stable numerical procedure. Our first objective is to investigate if the generally accepted formulations of the FSI problems are the only possible ones. Our second objective is to derive a numerical coupling which is truly stable. To accomplish that we will use a weak c...

0021-9991/$ see front matter 2011 Elsevier Inc doi:10.1016/j.jcp.2011.01.040 ⇑ Corresponding author. E-mail addresses: [email protected], [email protected] (S. Laizet). In this short note, we show how to use a highly accurate finite-difference scheme to compute second derivatives in the Navier–Stokes equations while ensuring targeted numerical dissipation. This approach, essenti...

In this paper we address the problem of producing an enlarged picture from a given digital image. We propose a zooming technique based on ENO and WENO schemes that are high order accurate finite difference schemes designed for problems with piecewise smooth solutions containing discontinuities. ENO and WENO schemes have been quite successful in applications, especially for problems containing b...

Since the direct numerical simulation (DNS) of aeroacoustic noise requires the numerical solution of the compressible Navier-Stokes equations in a large computational domain, it is computationally too demanding to solve computational aeroacoustics (CAA) applications using this technique only. In this paper a number of different hybrid approaches, where the computational domain is split into a s...