Abstract
Wormlike mioellar fluids formed by dissolving surfactants in water have unique mechanical responses due to its high surfactivity and strong viscoelasticity. These properties enable wormlike micellar fluids rich and complicated flow behaviors. By considering the breakage of long chains and the reforming of short chains, a two species VCM model is introduced in this study to numerically investigate the effect of the chain scission on the flow instability. First, the rheological properties are obtained by directly solving the VCM constitutive equation set numerically. The fluid exhibits a strong nonlinear thickening-thinning-thickening phenomenon under the uniaxial tension. The flow passing by a confined cylinder is investigated. The flow becomes significantly unstable at very low Reynolds numbers (Re ~0. 01) when the Weissenberg number is larger than 1. The fluid velocity in the downstream wake of the cylinder presents a fluctuation with the time. The flow fluctuation is quasi-periodic according to the power spectrum analysis. The flow fluctuation becomes more irregular when the nonlinearity of the variation of the tension stress with the elasticity becomes stronger. A pair of symmetrical vortexes behind the cylinder changing with time are also observed, indicating that the elasticity promotes the flow separation on the cylinder surface. The flow instability is due to the strong nonlinear response of the tension stress within the bulk fluid to the elasticity of the fluid.
| Translated title of the contribution | Study on the flow around a circular cylinder under the elastic micelle scission in surfactant solutions |
|---|---|
| Original language | Chinese (Traditional) |
| Pages (from-to) | 1194-1203 |
| Number of pages | 10 |
| Journal | Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics |
| Volume | 40 |
| Issue number | 5 |
| DOIs | |
| State | Published - 2023 |