A Tale of Molecules and Fluid

Yuan, Sheng

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https://hdl.handle.net/2142/99830 Copy

Description

Title

A Tale of Molecules and Fluid

Author(s)

Yuan, Sheng

Issue Date

2018-04

Keyword(s)

Mechanical Science and Engineering

Abstract

Solutions of flexible polymers like #-DNA can exhibit strikingly different flow patterns compared to Newtonian (e.g. water) flow because of the hydrodynamic interactions between the polymer molecules and solvent fluids. Here we present our experimental characterization of one such unique flow of #-DNA solution in a cross-channel microfluidic device, where a ‘modified’ flow pattern occurs due to molecular stretching. An image of the device, which consists of two opposing inlet channels and two opposing outlet channels (left and right), is set as the background with sidewalls shown in dark. Flow velocity distribution through the channels is overlaid onto the upper half of the channel cross. With cooler color representing slower flow and streamlines illustrating the flow direction, it’s shown that an elongated low-speed region is induced near the center. How do DNA molecules and fluid give birth to such an amazing flow? Measurement of a parameter called extensional strain rate in the lower section shows that the fluid generates strong extension in the red region. As a result, molecules undergo fast stretching as they travel near that region. The extension of molecules then reaches their maximum near the cross-channel center, significantly slowing down the local flow with additional resistance.

Type of Resource

• text
• image

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http://hdl.handle.net/2142/99830

Copyright and License Information

Copyright 2018 Sheng Yuan

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