Enhancing crossflow dynamics through the gas injection from multiple cylinders

We investigate unsteady, two-dimensional laminar fluid flow around cylinders, focusing on understanding the impact of injecting methane gas through two diametrically opposite arcs on the cylinder in the crossflow of the second fluid. This study encompasses applications in mixing and dispersion, which are crucial in various technological and natural processes. Our analysis addresses velocity field’s contribution to the spatiotemporal distribution of transported quantities. We observed that mixing induces a transition from laminar to turbulent flow. Depending on the injected-to-crossflow velocity ratios, the wake vortices downstream of cylinder arrays separate from or connect to the injected gas. This phenomenon significantly impacts mixing efficiency caused by asymmetric vortical flow structures and their interactions. In this study, the effective Reynolds number was computed at the outlet to account for the increase of momentum due to the gas injection, and it showed a monotonic rise with increasing injected gas velocity. Particularly, we observed a linear increase in the effective Reynolds number with increasing ϵ (velocity ratio parameter) for the single cylinder case, however, it exhibits a non-linear behavior for the multiple cylinders case due to complex flow interactions and enhanced mixing. We further analyzed flow disturbance using a participation number, a statistical characterization of the system’s spatial distribution of kinetic energy. Surprisingly, the participation number decreases with the increase in ϵ. This decrease indicates a highly localized and inhomogeneous distribution of kinetic energy in the system, increased tortuosity, and possibly the first sign of the inertial to turbulent transition in the system.