Breakup of small aggregates in fully developed turbulence is studied by means of direct numerical simulations in a series of typical bounded and unbounded flow configurations, such as a turbulent channel flow, a developing boundary layer, and homogeneous isotropic turbulence. The simplest criterion for breakup is adopted, whereby aggregate breakup occurs when the local hydrodynamic stress σ ∼ ε1/2, with ε being the energy dissipation at the position of the aggregate, overcomes a given threshold σcr, which is characteristic for a given type of aggregate. Results show that the breakup rate decreases with increasing threshold. For small thresholds, it develops a scaling behaviour among the different flows. For high thresholds, the breakup rates show strong differences between the different flow configurations, highlighting the importance of non-universal mean-flow properties. To further assess the effects of flow inhomogeneity and turbulent fluctuations, the results are compared with those obtained in a smooth stochastic flow. Furthermore, we discuss the limitations and applicability of a set of independent proxies.

Babler, M., Biferale, L., Brandt, L., Feudel, U., Guseva, K., Lanotte, A., et al. (2015). Numerical simulations of aggregate breakup in bounded and unbounded turbulent flows. JOURNAL OF FLUID MECHANICS, 766(2), 104-128 [10.1017/jfm.2015.13].

Numerical simulations of aggregate breakup in bounded and unbounded turbulent flows

BIFERALE, LUCA;
2015

Abstract

Breakup of small aggregates in fully developed turbulence is studied by means of direct numerical simulations in a series of typical bounded and unbounded flow configurations, such as a turbulent channel flow, a developing boundary layer, and homogeneous isotropic turbulence. The simplest criterion for breakup is adopted, whereby aggregate breakup occurs when the local hydrodynamic stress σ ∼ ε1/2, with ε being the energy dissipation at the position of the aggregate, overcomes a given threshold σcr, which is characteristic for a given type of aggregate. Results show that the breakup rate decreases with increasing threshold. For small thresholds, it develops a scaling behaviour among the different flows. For high thresholds, the breakup rates show strong differences between the different flow configurations, highlighting the importance of non-universal mean-flow properties. To further assess the effects of flow inhomogeneity and turbulent fluctuations, the results are compared with those obtained in a smooth stochastic flow. Furthermore, we discuss the limitations and applicability of a set of independent proxies.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici
English
Con Impact Factor ISI
Babler, M., Biferale, L., Brandt, L., Feudel, U., Guseva, K., Lanotte, A., et al. (2015). Numerical simulations of aggregate breakup in bounded and unbounded turbulent flows. JOURNAL OF FLUID MECHANICS, 766(2), 104-128 [10.1017/jfm.2015.13].
Babler, M; Biferale, L; Brandt, L; Feudel, U; Guseva, K; Lanotte, A; Marchioli, C; Picano, F; Sardina, G; Soldati, A; Toschi, F
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/174003
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