# Numerical simulations of aggregate breakup in bounded and unbounded turbulent flows

M.U. Babler, L. Biferale, L. Brandt, U. Feudel, K. Guseva, A.S. Lanotte, C. Marchioli, F. Picano, G. Sardina, A. Soldati, F. Toschi

## 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. Aggregate breakup occurs when the local hydrodynamic stress $\sigma\sim \varepsilon^{1/2}$, where $\varepsilon$ is the energy dissipation at the position of the aggregate, overcomes a given threshold $\sigma_\mathrm{cr}$, characteristic for a given type of aggregates. Results show that the breakup rate decreases with increasing threshold. For small thresholds, it develops a universal scaling among the different flows. For high thresholds, the breakup rates show strong differences among the different flow configurations, highlighting the importance of non-universal mean-flow properties. To further assess the effects of flow inhomogeneity and turbulent fluctuations, results are compared with those obtained in a smooth stochastic flow. Furthermore, we discuss limitations and applicability of a set of independent proxies.
Original language English s.n. 13 Published - 2014

### Publication series

Name arXiv 1406.2842 [physics.flu-dyn]

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