PROGRESS IN MOLECULAR DYNAMICS SIMULATIONS OF SURFACTANT SOLUTION FOR TURBULENT DRAG REDUCTION

Surfactant additives for turbulent drag reduction have been widely used in energy power and chemical industry. The addition of a small amount of surfactant additives in the pipeline fluid can greatly reduce the flow friction resistance and save energy. In recent years, the research on the mechanism of surfactant drag reduction is also a hot scientific topic. This paper not only summarized our work on the rheology of surfactant solution, surfactant drag reduction, the correlation with surfactant drag reduction and heat transfer, Brownian dynamics simulations in the latest years, but also concerning some works based on the coarse grained molecular dynamics (CGMD) simulations in the past three years, which will be elaborated in detail. The CGMD simulation is developed these years and now widely used in chemistry, biology and many other aspects. Our CGMD simulation work includes three parts, which are the rheology properties and its microstructures of the surfactant solution, the mechanism of turbulent drag reduction by surfactant additives, the analysis of turbulent drag reduction failure phenomenon on the pipeline transportation system. Through reviewing the progress in our CGMD simulation work, we believe that the CGMD simulation method can reasonably explain the rheological behavior of surfactant solutions, and the relationship between the rheology and the surfactant micelle structure can be well studied by using the coarse grained model. The breakage and the recombination behaviors of surfactant micelles can be evaluated from a multidimensional system including the extensional energy, the breakage energy, the maximum reasonable stretching distance, coalescence energy, zeta potential, or hydrophobic driving effect. Besides, the "viscoelasticity theory" can be proved from a molecular scale. Last but not least, the mechanism of turbulent drag reduction failure phenomenon can also be analyzed by CGMD simulation by simulating different failure reasons. At last, we summarize the CGMD simulation work on surfactant in recent years and then the direction of the future work about CGMD simulation work on surfactant is predicted.