The role of breakup and coalescence in fine-scale bubble-induced turbulence. I. Dynamics

We study the effect of bubble breakup and coalescence on fine-scale dynamics bubbly turbulent flows using direct numerical simulations. perform two different simulations dilute void fraction 0.5%: one with bubbles breaking up coalescing other without these physical processes. The volume fluid method is used for simulating undergoing while are treated as rigid spheres in immersed boundary simulation. energy spectrum both types simulation, consistent previous studies, exhibits a −3 slope. follow single infinitesimal element it evolves to understand velocity gradient conditional mean trajectories. note finite-time divergence when under action inertial pressure dynamics. inertial, pressure, viscous dynamics, considered individually, produce same results bubble-induced turbulence (BIT) classical homogeneous isotropic (HIT). Yet overall considered, BIT non-cyclic trajectories moving toward stable node unstable saddle HIT shows cyclic behavior their that move origin. Interestingly, similar results. Therefore, there main takeaways from this research. First, new models needed gradients entirely HIT. Second, we can neglect topology, breakup, studying or modeling BIT.