Motion of discrete particles in a turbulent fluid

Hjelmfelt, Allen T.; Mockros, Lyle F.

doi:10.1007/bf00384062

Cited by 301 publications

(104 citation statements)

References 4 publications

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“…Nondimensional parameters accounting for the relative importance of the particle relaxation time and these characteristic times, in turn, can be defined as (see Hjelmfelt and Mockros, 1966;Coimbra and Rangel, 2001):…”

Section: The Dispersed Phasementioning

confidence: 99%

On the variety of particle accumulation structures under the effect of g-jitters

Lappa¹

2013

J. Fluid Mech.

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The present analysis extends the author's earlier work (Lappa, Phys. Fluids 25(1) and Chaos 23(1)) 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 traveling wave propagating in the azimuthal direction) by considering the potential impact of "vibrations" (gjitters) 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 (vibrationless) conditions. It is shown that the resulting degree of "turbulence" depends essentially on the direction (), amplitude () and frequency () 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 - plane) for their occurrence is derived with the express intent of supporting the optimization of future experiments to be performed in space.

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Section: The Dispersed Phasementioning

confidence: 99%

On the variety of particle accumulation structures under the effect of g-jitters

Lappa¹

2013

J. Fluid Mech.

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“…Using this distance in a Stokes drag calculation, a particle size of 1.1 µm is found. Hjelmfelt and Mockros [17] analyzed the ability of a particle to follow the turbulence of a given frequency. With this particle size, a maximum turbulence frequency of 27 kHz is observable.…”

Section: Methodsmentioning

confidence: 99%

Influence of the Richtmyer-Meshkov instability on the kinetic energy spectrum.

Weber

2010

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The fluctuating kinetic energy spectrum in the region near the Richtmyer-Meshkov instability (RMI) is experimentally investigated using particle image velocimetry (PIV). The velocity field is measured at a high spatial resolution in the light gas to observe the effects of turbulence production and dissipation. It is found that the RMI acts as a source of turbulence production near the unstable interface, where energy is transferred from the scales of the perturbation to smaller scales until dissipation. The interface also has an effect on the kinetic energy spectrum farther away by means of the distorted reflected shock wave. The energy spectrum far from the interface initially has a higher energy content than that of similar experiments with a flat interface. These differences are quick to disappear as dissipation dominates the flow far from the interface.4 5

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“…For gaseous flows, it is usually ρ p ≫ ρ, so that Equation (6) can be simplified according to Hjemfelt and Mockros [152,153]. One component of the velocity then follows the relation: Figure 7.…”

Section: Flow Following Behaviormentioning

confidence: 99%

Imaging Flow Velocimetry with Laser Mie Scattering

Fischer

2017

Applied Sciences

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Abstract:Imaging flow velocity measurements are essential for the investigation of unsteady complex flow phenomena, e.g., in turbomachines, injectors and combustors. The direct optical measurement on fluid molecules is possible with laser Rayleigh scattering and the Doppler effect. However, the small scattering cross-section results in a low signal to noise ratio, which hinders time-resolved measurements of the flow field. For this reason, the signal to noise ratio is increased by using laser Mie scattering on micrometer-sized particles that follow the flow with negligible slip. Finally, the ongoing development of powerful lasers and fast, sensitive cameras has boosted the performance of several imaging methods for flow velocimetry. The article describes the different flow measurement principles, as well as the fundamental physical measurement limits. Furthermore, the evolution to an imaging technique is outlined for each measurement principle by reviewing recent advances and applications. As a result, the progress, the challenges and the perspectives for high-speed imaging flow velocimetry are considered.

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Motion of discrete particles in a turbulent fluid

Cited by 301 publications

References 4 publications

On the variety of particle accumulation structures under the effect of g-jitters

On the variety of particle accumulation structures under the effect of g-jitters

Influence of the Richtmyer-Meshkov instability on the kinetic energy spectrum.

Imaging Flow Velocimetry with Laser Mie Scattering

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