Dissertation defense of Chandra S. Kommineni (mechanical engineering department)

The near-wake of a slender ellipsoidal body is studied with and without high-intensity turbulence in the inflowing flow. Canonical broadband turbulence is generated using fractal grids and characterized by its turbulent kinetic energy balance and dissipation coefficient. Experimental data come from numerous PIV measurements and LDV time series.

By modeling the effect of spatial resolution on dissipation, PIV velocity fields are fully utilized to estimate spatial variations in turbulence properties, from the region of production to decreasing turbulence.

The analyses are based on statistics and structure functions, but more particularly on an empirical mode decomposition extended to 2D data.

These empirical modes, combined with the Hilbert transform, provide local spectra as well as wave vector fields and their corresponding amplitude.

These methods, little developed in the study of detached flows, are nevertheless particularly useful for identifying turbulent dynamics and scales in the wake of the slender body and attempting to differentiate it from free-flow turbulence.

Mr Laurent KEIRSBULCK (Université Polytechnique Hauts de France), Thesis co-director
. Mme Bérengère PODVIN (EM2C Laboratory - CentraleSupélec), Rapporteur
Mr. Luc PASTUR (ENSTA Paris), Rapporteur
Mr. Jack LEGRAND (Université de Paris), Rapporteur Mr. Jack LEGRAND (University of Nantes), Examiner
Mr. Fethi ALOUI (ENSTA Paris), Rapporteur Mr. Fethi ALOUI (Université Polytechnique Hauts de France), Thesis co-director
Mr. Jeremy BASLEY (Université Polytechnique Hauts de France), Examiner Mr Jeremy BASLEY (Université Polytechnique Hauts de France), Thesis co-supervisor
Mr Martin OBLIGADO (Université Polytechnique Hauts de France), Thesis co-supervisor Mr. Martin OBLIGADO (Centrale Lille), Guest
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