Multi-scale approach for the rheological characteristics of emulsions using molecular
dynamics and lattice Boltzmann method |
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| Authors: | Se Bin Choi Hong Min Yoon Joon Sang Lee |
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| Institution: | Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea |
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| Abstract: | An emulsion system was simulated under simple shear rates to analyze its rheological
characteristics using a hierarchical multi-scale approach. The molecular dynamics (MD) simulation
was used to describe the interface of droplets in an emulsion. The equations derived from the MD
simulation relative to interfacial tension, temperature, and surfactant concentration were applied
as input parameters within lattice Boltzmann method (LBM) calculations. In the LBM simulation, we
calculated the relative viscosity of an emulsion under a simple shear rate along with changes in
temperature, shear rate, and surfactant concentration. The equations from the MD simulation showed
that the interfacial tension of the droplets tended to decrease with an increase in temperature and
surfactant concentration. The relative viscosity from the LBM simulation decreased with an increase
in temperature. The shear thinning phenomena explaining the inverse proportion between shear rate
and viscosity were observed. An increase in the surfactant concentration caused an increase in the
relative viscosity for a decane-in-water emulsion, because the increased deformation caused by the
decreased interfacial tension significantly influenced the wall shear stress. |
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