AbstractThe present analysis extends the author’s earlier work (Lappa, Phys. Fluids, vol. 25, 2003, 012101; Lappa, Chaos, vol. 23, 2003, 013105) on the properties of patterns formed by the spontaneous accumulation and ordering of solid particles in certain types of flow (with a toroidal structure and a travelling wave propagating in the azimuthal direction) by considering the potential impact of ‘vibrations’ (g-jitters) on such dynamics. It is shown that a kaleidoscope of possible variants exist whose nature and variety calls for a concerted analysis using the tools of computational fluid dynamics in synergy with dimensional arguments and existing theories on the effect of periodic accelerations on fluid systems. A possible categorization of the observed phenomena is introduced according to the type and scale of ‘defects’ displayed by the emerging particle aggregates with respect to unperturbed (vibration-less) conditions. It is shown that the resulting degree of ‘turbulence’ depends essentially on the direction $(\phi )$, amplitude $(\gamma )$ and frequency $(\varpi )$ of the applied inertial disturbance. A range of amplitudes and frequencies exist where the formation of recognizable particle structures is prevented. A quantitative map (in the $\gamma \text{{\ndash}} \varpi $ plane) for their occurrence is derived with the express intent of supporting the optimization of future experiments to be performed in space.
Parametric Investigation Using Computational Fluid Dynamics of the HVAC Air Distribution in a Railway Vehicle for Representative Weather and Operating Conditions
