Turbulent drag reduction characteristics of poly(acrylamide-co-acrylic acid) in a rotating disk apparatus

Polymeric Drift Control Adjuvants for Agricultural Spraying

“…The resulting reduction in molecular weight has been observed through a decrease in drag reduction and viscosity of polymer solutions along with GPC and birefringence measurements. [98,[101][102][103] In the case of agricultural spraying, mechanical degradation can occur as the polymer solution exits the spray nozzle. In fact as is shown in Figure 14 the desired strain hardening behaviour is often accompanied by mechanical degradation (for contraction flows such as nozzles and porous media) meaning this may be largely unavoidable.…”

Turbulent Drag Reduction with Polymers in Rotating Disk Flow

“…As shown in Figures 3 and 4, beyond the certain polymer concentration, a further increase in concentration leads to a leveling-off or a decrease in the DR. Above this concentration, the DR efficiency tends to decrease [54,55]. This behavior is considered to be due to the combination of two factors: the initial increase in DR is presumably due to the increasing number of polymer molecules present, which causes the decay of turbulent eddies, whereas the shear viscosity becomes increasingly significant at higher concentrations of polymer, and the Reynolds number decreases compared to that of the initial state.…”

“…This behavior is considered to be due to the combination of two factors: the initial increase in DR is presumably due to the increasing number of polymer molecules present, which causes the decay of turbulent eddies, whereas the shear viscosity becomes increasingly significant at higher concentrations of polymer, and the Reynolds number decreases compared to that of the initial state. Furthermore, the overshoot of the DR at c = 50 ppm for Figure 4 was explained by the Brownian dynamics simulation results showing that partial disentanglement of entanglements that existed at rest takes place in flow [29,55,56]. Zhang et al [55] considered that further addition of the DR agent does not change that DR efficiency since much of the solvent is already solvated by the DR agent chains.…”

Water Soluble Polymers

“…Reactivity ratios for this system were not available in the literature. However, there are related systems: 2VP with OEGMA (300 and 1100) had r 2VP = 0.99-1.13, r OEGMA300 = 0.16-0.25 [68]. Regardless, tuning for this system is relatively predictable.…”

“…Recently, Zhang et al [68,69] studied the turbulent DR efficiency of aqueous poly(acrylamide-coacrylic acid) copolymers with various molecular parameters in a rotating disk flow system, and found a maximum DR of 45% at 50 wppm concentration. The influence of temperature on the drag reduction efficacy is presented in Figure 13.…”