Onion-like Structure Flow of Viscoelastic Surfactant Solutions Induced by 4-Blade Paddle Impeller in a Vessel

概要

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Aqueous solutions of some kinds of surfactant and counter ion are known as viscoelastic fluids. The rheological properties and fluidity are significantly affected by the concentrations of surfactant and counter ion. Thus, the solution is a potential solvent for industrial applications because drastic change in fluidity can be realized only with the addition of counter ion. In this study, we focused on characteristics of fluid flow of viscoelastic surfactant solutions in a mixing vessel. It was found that the vicinity to the impeller was actively mixed and covered by laminated fluid lump, forming onion-like structure. When elastic force becomes comparative to viscous force, the micellar network of surfactant is deformed. Additionally, if the elastic force is not much smaller than inertia force, the impeller region was covered by the network deformed fluid and then the onion-like structure is formed. Moreover, stable onion-like structure will obtain when the impeller rotates as slow as possible or t he elastic effect of the solution is more significant than viscous one.