The development of a wind turbine aerodynamics model using a Boundary Integral Equation model (BIEM) is presented. The methodology is valid to study inviscid unsteady flows around three dimensional bodies of arbitrary shape and arbitrarily moving with respect to the incoming flow. The extension of this methodology to study viscosity effects in turbine blade flow at high angle of attack is addre...

The multi-size-mesh multi-time-step DRP scheme (Tam&Kurbatskii2003) is suited for numerical simulations of multiple-scales aeroacoustics problems. In regions where there are high flow gradients (jet or flow near walls), small grid sizes to resolve small scales are needed. In regions where sound dominates, larger grid sizes for long sound wave lengths may be used to save computation resources. T...

The ability of popular computational fluid dynamic (CFD) methods t o simulate the propagation of acoustic waves is assessed both theoretically and by numerical experiment. The schemes are used to model acoustic waves generated by a noise source situated at the aft end of a convergent-divergent nozzle. It is found that the acoustic signal that traverses up the nozzle has difficulty maintaining i...

Correction Procedure via Reconstruction (CPR) is a differential discontinuous formulation for conservation laws. In this paper, a recently developed optimized CPR scheme, named frequency optimized CPR (FOCPR), was employed and tested. The idea is to resolve the broadest range of wave frequencies on a given mesh given an acceptable error threshold. In the FOCPR method, both polynomial and Fourie...

We develop high order accurate source discretizations for hyperbolic wave propagation problems in first order formulation that are discretized by finite di↵erence schemes. By studying the Fourier series expansions of the source discretization and the finite di↵erence operator, we derive su cient conditions for achieving design accuracy in the numerical solution. Only half of the conditions in F...

The computers of today make it possible to do direct simulation of aeroacoustics, which is very computationally demanding since a very high resolution is needed. In the present thesis we study issues of relevance for aeroacoustic simulations. Paper A considers standard high order difference methods. We study two different ways of applying boundary conditions in a stable way. Numerical experimen...

We study the asymptotic behavior and the asymptotic stability of the two-dimensional Euler equations and of the two-dimensional linearized Euler equations close to parallel flows. We focus on flows with spectrally stable profiles U (y) and with stationary streamlines y = y0 (such that U ′(y0) = 0), a case that has not been studied previously. We describe a new dynamical phenomenon: the depletio...

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 fluid structure interaction problem are the only possible ones. Our second objective is to derive a stable numerical coupling. To accomplish that we will use ...

Since its introduction the Perfectly Matched Layer (PML) has proven to be an accurate and robust method for domain truncation in computational electromagnetics. However, the mathematical analysis of PMLs has been limted to special cases. In particular, the basic question of whether or not a stable PML exists for arbitrary wave propagation problems remains unanswered. In this work we develop gen...

Passive acoustic aircraft and wake localization methods rely on the noise emission from their wakes for detection, tracking, characterization. This paper takes a holistic approach to passive first presents systematic bibliographic review of aeroacoustic drones, followed by summary sound generation wing tip vortices. The propagation through atmosphere is then summarized. techniques utilize an ar...