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Abstract
A highorder finite difference method to predict flowgenerated noise is introduced in this thesis. The technique consists of solving the viscous incompressible flow equations and inviscid acoustic equations using an incompressible/acoustic splitting technique. The incompressible flow equations are solved using the inhouse flow solver EllipSys2D/3D which is a secondorder finite volume code. The acoustic equations are solved using highorder finite difference schemes. The incompressible flow equations and the acoustic equations are solved at the same time levels where the pressure and the velocities obtained from the incompressible equations form the input to the acoustic equations. To achieve low dissipation and dispersion errors, either DispersionRelationPreserving (DRP) schemes or optimized compact finite difference schemes are used for spatial discretizations of the acoustic equations. The acoustic solver consists of numerical schemes from fourthorder up to tenthorder accuracy, the use of different schemes are case dependent. In practice, at high Reynolds numbers when flow becomes turbulent, schemes with the highest order of accuracy are always used to resolve the small waves. For time integration, the classical 4stage RungeKutta scheme is applied. Noncentered highorder schemes at numerical boundaries and highorder filter schemes are also discussed due to their importance.
The method was validated against a few test cases and further applied for flows around a cylinder and an airfoil both for laminar and turbulent flows. Results have shown that sound generation is due to the unsteadiness of the flow field and the spectrum of sound has a strong relation with fluctuating forces on the solid body. Flow and acoustic simulation were also carried out for a wind turbine where general trends of sound generation from blades was found.
Original language  English 

Number of pages  138 

ISBN (Print)  9788774753483 
Publication status  Published  Mar 2008 
Series  MEKFMPHD 

Number  200702 
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Projects
 1 Finished

DCAMM
Zhu, W. J., Shen, W. Z., Sørensen, J. N., Sørensen, N. N., Ekaterianris, I. A. & Thomsen, P. G.
01/06/2004 → 07/03/2008
Project: PhD