Implementation of an automated post-processing workflow for wake dynamics and modal analysis of bluff-body simulations in OpenFOAM

This thesis investigates the post-processing and analysis of numerical simulations of upstream Dielectric Barrier Discharge (DBD) plasma actuators applied to a square cylinder with rounded leading edges. Plasma actuators are an active flow-control technology capable of increasing near-wall momentum and modifying boundary layer development, with the potential to delay or alter flow separation and reduce aerodynamic drag. The study analyzes both baseline (unactuated) and actuated flow configurations, focusing on wake topology, vortex shedding dynamics, and global flow behavior. Particular attention is devoted to understanding how plasma actuation modifies the dominant coherent structures in the wake and influences the natural instability mechanisms of the flow. A central contribution of this work is the development of an automated Python-based framework for pre-processing and post-processing of the simulation data. Custom scripts were created to automate mesh preparation, boundary condition setup, batch execution of simulations, and structured storage of results. This workflow reduces manual intervention, improves reproducibility, and facilitates efficient parametric studies. For the analysis phase, dedicated Python tools were implemented to perform spectral and modal decomposition techniques, including Fast Fourier Transform (FFT), Proper Orthogonal Decomposition (POD), and Dynamic Mode Decomposition (DMD). These methods enable the identification of dominant frequencies, coherent flow structures, and energy distribution across modes. The results show that upstream plasma actuation significantly alters wake dynamics by attenuating the dominant vortex shedding modes and redistributing modal energy toward higher-frequency actuation-driven structures, contributing to wake stabilization and potential drag reduction.