Formation–breakdown cycle of turbulent jets in a rotating fluid

Abstract

Results of comprehensive particle image velocimetry measurements investigating the dynamics of turbulent jets in a rotating fluid are presented. It is observed that background system rotation induces a time-periodic formation–breakdown cycle of the jets. The flow dynamics associated with this process is studied in detail. It is found that the frequency of the cycle increases linearly with the background rotation rate. The data show that the onset of the breakdown phase and of the reformation phase of the cycle can be characterized in terms of a local Rossby number employing an internal velocity and a length scale of the jet. The critical values for this local Rossby number, for onset of breakdown and reformation, scale linearly with a global Rossby number based on the flow conditions at the source. The analysis of the experimental data suggests centrifugal instability as the potential origin of the formation–breakdown cycle.

Molecular Signal Tracking and Detection Methods in Fluid Dynamic Channels

“…Once the basic velocity field is known as a function of time, other quantities such as time averaged velocities, the vorticity or the turbulence characteristics can be obtained from postprocessing of the collected data. An in-depth example showing such results from a PIV study is discussed in [34].…”

“…This is required such that the particles always faithfully follow the flow and therefore accurately represent the flow velocity at their locations within the flow field [33]. In liquids one can use, for instance, hollow-glass spheres as seeding particles, which can be silver-coated to increase their reflectivity as is the case in the experiments of [4], [34]. If the flow is in a gas, then it is not possible to satisfy the requirement for neutral buoyancy and one typically uses, for instance, micronsized oil droplets as tracer particles.…”

Local wave-number model for inhomogeneous two-fluid mixing

“…MOBILE has been shown to accurately predict global flow features such as symmetry break-down of rising bubbles and spikes in the single mode RT simulation at Atwood numbers upto 0.5 [44]. Further, MOBILE has been validated for several fluid mixing and transport problems including single-mode and multimode Rayleigh-Taylor flows up to Atwood A = 0.9 [44,45,48,50], Kelvin-Helmholtz instability [44], lock-release gravity currents [44], systems with unusual geometries [45], jet flows with background flows [52,53], and systems with variable acceleration [54]. For additional details on these methods and codes, the reader is referred to Refs.…”

Local Wave Number Model for Inhomogeneous Two-Fluid Mixing

“…lock-release gravity currents [31], systems with unusual geometries [32], jet flows with background flows [40,41], and systems with variable acceleration [42]. For additional details on these methods and codes, the reader is referred to [31][32][33]38].…”