Development and validation of a phase shift and attenuation free filtering for exploitation of CFD data

Abstract

A causal filtering method is developed to perform decimation and storage of aerodynamic data without signal distortion. When done without precaution, decimation of instantaneous computed flow fields for storage and subsequent exploitation generates aliasing. Use of a low-pass filter limits the creation of spurious noise but attenuates signal amplitudes and shifts phases. The proposed filtering method combines the application of a low-pass filter before decimation, during the aerodynamic simulation, with that of a corrective filter, applied in the frequency domain after the full storage. This corrective filter is designed to correct attenuation and phase distortion caused by the low-pass filter. The method is validated on analytical signals and successfully applied to turbulent shear layer and noise radiation problems.