Characteristics of force coefficients and energy transfer for vortex shedding modes of a square cylinder subjected to inline excitation

The nature of the circulation regions around a bluff body in a cross flow can vary considerably from the normal von Kármán vortex-shedding mode when subjected to external excitations. The dynamics of the circulation regions around the bluff body has a direct impact on the force coefficients of the bluff body. In the present work, we correlate the spectral content and characteristics of the force coefficients of different vortex-shedding modes, observed for a square cylinder that is subjected to external excitation in the form of inline sinusoidal pulsation, to the near body vortical events. The strengths of various circulation regions around the bluff body and its location of formation are used to assess the impact of the vortical events on the force coefficient characteristics. In addition, the implication of relative timing of vortical events with respect to the inline excitation on the energy transfer is also discussed.