On bubble clustering and energy spectra in pseudo-turbulence
| Autor: | Dennis P. M. van Gils, Julian Martinez Mercado, Daniel Chehata Gomez, Detlef Lohse, Chao Sun |
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| Přispěvatelé: | Physics of Fluids, Faculty of Science and Technology |
| Rok vydání: | 2010 |
| Předmět: |
Physics
Homogeneous isotropic turbulence Turbulence IR-79266 Computer Science::Information Retrieval Mechanical Engineering Bubble Fluid Dynamics (physics.flu-dyn) FOS: Physical sciences Probability density function METIS-266193 Physics - Fluid Dynamics Condensed Matter Physics Radial distribution function Power law Computational physics law.invention Physics::Fluid Dynamics Mechanics of Materials law Particle tracking velocimetry Intermittency |
| Zdroj: | Journal of fluid mechanics, 650, 287-306. Cambridge University Press |
| ISSN: | 0022-1120 |
| DOI: | 10.1017/s0022112009993570 |
| Popis: | Three-dimensional particle tracking velocimetry (PTV) and phase-sensitive constant temperature anemometry in pseudo-turbulence – i.e. flow solely driven by rising bubbles – were performed to investigate bubble clustering and to obtain the mean bubble rise velocity, distributions of bubble velocities and energy spectra at dilute gas concentrations (α ≤ 2.2 %). To characterize the clustering the pair correlation function G(r, θ) was calculated. The deformable bubbles with equivalent bubble diameter db = 4–5 mm were found to cluster within a radial distance of a few bubble radii with a preferred vertical orientation. This vertical alignment was present at both small and large scales. For small distances also some horizontal clustering was found. The large number of data points and the non-intrusiveness of PTV allowed well-converged probability density functions (PDFs) of the bubble velocity to be obtained. The PDFs had a non-Gaussian form for all velocity components and intermittency effects could be observed. The energy spectrum of the liquid velocity fluctuations decayed with a power law of −3.2, different from the ≈ −5/3 found for homogeneous isotropic turbulence, but close to the prediction −3 by Lance & Bataille (J. Fluid Mech., vol. 222, 1991, p. 95) for pseudo-turbulence. |
| Databáze: | OpenAIRE |
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