Jon Brons | The Hague University of Applied Sciences (original) (raw)
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Papers by Jon Brons
Bulletin of the American Physical Society, 2014
We report experimental results on the Lagrangian dynamics of finite-size light particles in turbu... more We report experimental results on the Lagrangian dynamics of finite-size light particles in turbulence. Using an orthogonal camera setup and 3D particle tracking, we study the velocity and acceleration statistics of rigid light spheres in a water tunnel with nearly homogeneous and isotropic turbulence. The Reynolds number (Re ) is varied from 180 to 300, and the study covers a range of size ratios (4 < < 16) for marginally light spheres. We find that the normalized acceleration PDF decreases in intermittency with increasing size ratio - in qualitative agreement with the predictions of the Faxen corrected model (1). We also present preliminary results on the rotational dynamics of large light spheres in turbulence. INTRODUCTION, MOTIVATION AND EXPERIMENTS Particles dispersions in turbulent flows exist in many natural situations - typical examples include pollutants dispersed in the atmosphere, droplet suspensions in clouds, and air bubbles and plankton in the oceans. Particle s...
Physical review letters, Jan 8, 2016
We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and trac... more We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St≪1 in turbulent flow. At a decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles; i.e., they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through t...
Physical Review Letters, 2016
We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and trac... more We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St≪1 in turbulent flow. At a decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles; i.e., they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through the turbulent oceans and the atmosphere. They also question the common usage of microbubbles and microdroplets as tracers in turbulence research.
Physical Review Letters, 2015
Bulletin of the American Physical Society, 2014
We report experimental results on the Lagrangian dynamics of finite-size light particles in turbu... more We report experimental results on the Lagrangian dynamics of finite-size light particles in turbulence. Using an orthogonal camera setup and 3D particle tracking, we study the velocity and acceleration statistics of rigid light spheres in a water tunnel with nearly homogeneous and isotropic turbulence. The Reynolds number (Re ) is varied from 180 to 300, and the study covers a range of size ratios (4 < < 16) for marginally light spheres. We find that the normalized acceleration PDF decreases in intermittency with increasing size ratio - in qualitative agreement with the predictions of the Faxen corrected model (1). We also present preliminary results on the rotational dynamics of large light spheres in turbulence. INTRODUCTION, MOTIVATION AND EXPERIMENTS Particles dispersions in turbulent flows exist in many natural situations - typical examples include pollutants dispersed in the atmosphere, droplet suspensions in clouds, and air bubbles and plankton in the oceans. Particle s...
Physical review letters, Jan 8, 2016
We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and trac... more We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St≪1 in turbulent flow. At a decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles; i.e., they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through t...
Physical Review Letters, 2016
We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and trac... more We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St≪1 in turbulent flow. At a decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles; i.e., they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through the turbulent oceans and the atmosphere. They also question the common usage of microbubbles and microdroplets as tracers in turbulence research.
Physical Review Letters, 2015