Phong Pham - Academia.edu (original) (raw)
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Papers by Phong Pham
Bulletin of the American Physical Society, 2014
FRANCE. COLLABORATION, UNIVERSITY OF FLORIDA-GAINESVILLE COLLABORATION-We investigate experimenta... more FRANCE. COLLABORATION, UNIVERSITY OF FLORIDA-GAINESVILLE COLLABORATION-We investigate experimentally the evolution of small clouds of non-Brownian particles submitted to a periodic shear under low Reynolds number conditions. The particle motion is irreversible during the first cycle. Beyond that, the particle motion is reversible. We find that the amount of irreversibility increases as the particle roughness is increased. An accurate prediction of the particles' trajectories is obtained with a minimal model including normal lubrication and a frictionless contact force. These experiments provide evidence that, in viscous flows, contacts between particles occur and strongly influence the particle dynamics.
Physical Review Fluids, 2016
The role of solid-solid contacts on the transition between reversible and irreversible dynamics o... more The role of solid-solid contacts on the transition between reversible and irreversible dynamics occurring in periodically sheared suspensions is investigated experimentally by modifying the particle roughness. Smoother particles lead to a larger critical strain amplitude. A geometrical model based on the assumption that colliding particles produce irreversibility is derived. The model, which considers a 'quasi-particle' having a strain and roughness dependent effective-volume, successfully reproduces the measured values of the critical strain amplitude as functions of the volume fraction and particle roughness.
Physical Review Fluids, 2016
We revisit Taylor's experiment investigating the evolution of a blob of dye in a periodically she... more We revisit Taylor's experiment investigating the evolution of a blob of dye in a periodically sheared suspension of non-Brownian particles. Above a critical strain amplitude, particulate suspensions are subject to phase transition where reversibility is lost and particles fail to return to their original positions. We investigate the effect of this transition on the dispersion of a blob of dye. Beyond the critical strain, the dispersion of the blob is found to increase significantly. The dispersion coefficient of the blob of dye is measured and compared to the self-diffusivity coefficient of the particles.
Physical Review E, 2013
We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Follo... more We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Following Metzger & Butler [Phys. Rev. E 82, 051406], we show that the chaotic dynamics arising from lubrication interactions are too weak to generate an observable particle dispersion. The irreversibility observed in periodic flow is dominated by contact interactions. Nonetheless, we show that lubrication interactions must be included in the calculation to obtain results that agree with experiments.
Bulletin of the American Physical Society, 2014
FRANCE. COLLABORATION, UNIVERSITY OF FLORIDA-GAINESVILLE COLLABORATION-We investigate experimenta... more FRANCE. COLLABORATION, UNIVERSITY OF FLORIDA-GAINESVILLE COLLABORATION-We investigate experimentally the evolution of small clouds of non-Brownian particles submitted to a periodic shear under low Reynolds number conditions. The particle motion is irreversible during the first cycle. Beyond that, the particle motion is reversible. We find that the amount of irreversibility increases as the particle roughness is increased. An accurate prediction of the particles' trajectories is obtained with a minimal model including normal lubrication and a frictionless contact force. These experiments provide evidence that, in viscous flows, contacts between particles occur and strongly influence the particle dynamics.
Physical Review Fluids, 2016
The role of solid-solid contacts on the transition between reversible and irreversible dynamics o... more The role of solid-solid contacts on the transition between reversible and irreversible dynamics occurring in periodically sheared suspensions is investigated experimentally by modifying the particle roughness. Smoother particles lead to a larger critical strain amplitude. A geometrical model based on the assumption that colliding particles produce irreversibility is derived. The model, which considers a 'quasi-particle' having a strain and roughness dependent effective-volume, successfully reproduces the measured values of the critical strain amplitude as functions of the volume fraction and particle roughness.
Physical Review Fluids, 2016
We revisit Taylor's experiment investigating the evolution of a blob of dye in a periodically she... more We revisit Taylor's experiment investigating the evolution of a blob of dye in a periodically sheared suspension of non-Brownian particles. Above a critical strain amplitude, particulate suspensions are subject to phase transition where reversibility is lost and particles fail to return to their original positions. We investigate the effect of this transition on the dispersion of a blob of dye. Beyond the critical strain, the dispersion of the blob is found to increase significantly. The dispersion coefficient of the blob of dye is measured and compared to the self-diffusivity coefficient of the particles.
Physical Review E, 2013
We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Follo... more We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Following Metzger & Butler [Phys. Rev. E 82, 051406], we show that the chaotic dynamics arising from lubrication interactions are too weak to generate an observable particle dispersion. The irreversibility observed in periodic flow is dominated by contact interactions. Nonetheless, we show that lubrication interactions must be included in the calculation to obtain results that agree with experiments.