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ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
POD ANALYSIS OF COHERENT STRUCTURES AND AEROACOUSTIC SOURCES IN A TURBULENT FLOW OVER A NACA0012 AIRFOIL
Submission Author:
Jean Ribeiro , SP
Co-Authors:
William Wolf
Presenter: Jean Ribeiro
doi://10.26678/ABCM.ENCIT2016.CIT2016-0063
Abstract
Turbulence is a flow regime characterized by chaotic flow with three-dimensional vorticity and broad range of frequencies and spatial scales. Large Eddy Simulations (LES) are capable to solve the most energy containing large scales of the flow while filtering the dissipative small ones. Extracting physical and useful information from LES data requires the use of statistical analysis. A high-fidelity numerical simulation database of low and moderate Mach number flows past a NACA0012 airfoil is investigated in the present work. Although turbulence is three-dimensional, fully turbulent flows may have coherent structures with two-dimensional characteristics. In the present studies, two-dimensional aeroacoustic sources in the near wake region generate tonal noise. These sources are identified on acoustic field, but are not easily visualized in the hydrodynamic field. A three-dimensional vectorial Proper Orthogonal Decompostion (POD) is constructed for the present compressible flow simulations to identify coherent structures near the trailing edge. Norms are defined based on volume integrals of turbulent kinetic energy or pressure. The different structures captured by both norms are presented and discussed via a two-dimensional analysis. The most energy containing POD modes are capable of capturing large two-dimensional coherent structures appearing due to the blunt trailing edges. Farfield analysis is performed using the Ffowcs-Williams and Hawkings Analogy
Keywords
POD, LES, Aeroacoustics, Coherent Structures, Turbulence, POD, LES, Aeroacoustics, Coherent Structures, Turbulence, Coherent Structures, POD, LES, Turbulence, Aeroacoustics
