Intermittent dynamics driven by internal stress imbalances in disordered systems is a fascinating yet poorly understood phenomenon. Here, we study it for a coarsening foam. By exploiting differential dynamic microscopy and particle tracking we determine the dynamical characteristics of the foam at different ages in reciprocal and direct space, respectively. At all wavevectors $q$ investigated, the intermediate scattering function exhibits a compressed exponential decay. However, the access to unprecedentedly small values of $q$ highlights the existence of two distinct regimes for the $q$-dependence of the foam relaxation rate $Gamma (q)$. At high $q$, $Gamma (q)sim q$ consistent with directionally-persistent and intermittent bubble displacements. At low $q$, we find the surprising scaling $Gamma (q) sim q^{delta}$, with $delta=1.6 pm 0.2$. The analysis of the bubble displacement distribution in real space reveals the existence of a displacement cut-off of the order of the bubble diameter. Introducing such cut-off length in an existing model, describing stress-driven dynamics in disordered systems, fully accounts for the observed behaviour in direct and reciprocal space.

Multiple dynamic regimes in a coarsening foam / F. Giavazzi, V. Trappe, R. Cerbino. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - 33:2(2021 Jan 13), pp. 024002.1-024002.9. [10.1088/1361-648X/abb684]

Multiple dynamic regimes in a coarsening foam

F. Giavazzi
Primo
;
R. Cerbino
Ultimo
2021

Abstract

Intermittent dynamics driven by internal stress imbalances in disordered systems is a fascinating yet poorly understood phenomenon. Here, we study it for a coarsening foam. By exploiting differential dynamic microscopy and particle tracking we determine the dynamical characteristics of the foam at different ages in reciprocal and direct space, respectively. At all wavevectors $q$ investigated, the intermediate scattering function exhibits a compressed exponential decay. However, the access to unprecedentedly small values of $q$ highlights the existence of two distinct regimes for the $q$-dependence of the foam relaxation rate $Gamma (q)$. At high $q$, $Gamma (q)sim q$ consistent with directionally-persistent and intermittent bubble displacements. At low $q$, we find the surprising scaling $Gamma (q) sim q^{delta}$, with $delta=1.6 pm 0.2$. The analysis of the bubble displacement distribution in real space reveals the existence of a displacement cut-off of the order of the bubble diameter. Introducing such cut-off length in an existing model, describing stress-driven dynamics in disordered systems, fully accounts for the observed behaviour in direct and reciprocal space.
Anomalous relaxation; Foams; Quantitative microscopy; Soft jammed materials; Stress-driven dynamics;
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
   All-optical fingerprinting of metastatic potential (1° anno)
   FONDAZIONE AIRC PER LA RICERCA SUL CANCRO ETS
   MFAG 2018 Id.22083
13-gen-2021
26-ott-2020
https://iopscience.iop.org/article/10.1088/1361-648X/abb684
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/950916
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