Drag reduction by linear flexible polymers and its degradation in turbulent flow: A phenomenological explanation from chemical thermodynamics and kinetics

Based on chemical thermodynamics and kinetics analysis, this work provides a phenomenological explanation of drag reduction and its degradation by linear flexible polymers. We propose that drag reduction happens due to the unstable thermodynamic environment created by the elongation of free polymers and aggregates, and degradation of drag reduction happens due to the unstable kinetic environment with the chain scission of the free polymer and aggregate. Experimental results from microscopic and macroscopic scales further validate the proposed theory. Fourier series is employed to explain the molecular weight distribution that happens in the drag reduction.