Weakening or losing of surfactant drag reduction ability: A coarse- grained molecular dynamics study
F Liu and DJ Liu and WJ Zhou and S Wang and F Chen and JJ Wei, CHEMICAL ENGINEERING SCIENCE, 219, 115610 (2020).
Surfactant drag reduction has wide applications in energy power and chemical industries. However, the drag reduction ability will be weakened or lost during long-term applications. We studied the surfactant drag reduction in turbulent pipe flow using coarse-grained molecular dynamics simulations and cryogenic transmission electron microscopy experiments. The results show that the weakening/loss of surfactant drag reduction ability occurs under the following conditions: weak alkalinity of the solution, tiny rust particles in the solution, and/or the rusty wall of the pipeline. Weak alkalinity conduces to irregular structures of surfactant micelles, charged tiny iron rust particles can adsorb the surfactant micelles and fill into micelle network gaps, and the rusty wall could adsorb part of the surfactant micelles and lessen the global micelle network structure. All the three can destroy the micelle network structure and result in partial or complete failure of the turbulent drag reduction. (C) 2020 Elsevier Ltd. All rights reserved.
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