Mesoscopic simulation of the transient behavior of semi-diluted polymer solution in a microchannel following extensional flow

S Litvinov and XY Hu and M Ellero and N Adams, MICROFLUIDICS AND NANOFLUIDICS, 16, 257-264 (2014).

DOI: 10.1007/s10404-013-1207-8

Using dissipative particle dynamics simulation, we investigate the transient behavior of a semi-dilute polymer solution in a microchannel at moderate Weissenberg numbers. The employed simulation method allows to study macroscopic properties of the solution and their relation to the microscopic properties of individual polymer. The solution enters the channel following an extensional flow with all polymers uniformly stretched. We observe that the shape of the velocity profile varies along the channel, from an almost parabolic to center-flattened type. The fully developed velocity profile at equilibrium is accurately described by the Carreau-Yasuda rheological model. We find that the relaxation time for the profile shape is equal to the relaxation time of the polymer extension in the flow direction. The established relation offers the potential to be utilized for microfluidics-based rheometers which measure, besides the steady solution rheology, also the polymer relaxation time using flow velocity data only.

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