Extremely slow settling behavior of particles in dilute wormlike micellar fluid with broad spectrum of relaxation times

Perspectives on viscoelastic flow instabilities and elastic turbulence

“…This N 1 peak coincides in location with a fluidity maximum, which, under extensional deformation and the BMP+ τ p formalism, reflects an evolution in the increase of Wi that follows the strain-hardening/softening of extensional viscosity [447]. Such a complex interplay between the change in a localized material property and mixed deformations may take a role in further understanding the instabilities observed experimentally when a sphere settles in WLMs [206,207,209,431,[436][437][438][439][440][441] and polymer solutions [506].…”

“…Experimental studies of the sedimentation of smooth spheres in WLM solutions report a common phenomenology of sphere oscillations beyond a critical speed threshold and strong negative wakes behind the sphere [206,207]. Such observations have been attributed to complex dynamics in the construction and destruction of the fluid's internal structure and its viscoelasticity, measured through an extensionally-based Deborah number, which permits consistent steady-tounsteady flow classification [209,[436][437][438][439][440][441]. These features have been little explored computationally, with the first studies provided by Sasmal [442], using the Vasquez-Cook-McKinley (VCM) [443][444][445][446] and Giesekus models, and by Lpez-Aguilar et al for the BMP+ τ p model [447].…”

Unsteady motion past a sphere translating steadily in wormlike micellar solutions: a numerical analysis

“…This reason was further established in a later study with cetylpyridinium chloride (CPyCl)/NaSal WLM solution by Wu & Mohammadigoushki (2018). The unsteady motion of a falling sphere was also observed in the study by Kumar et al (2012) with cetyl trimethyl ammonium p-toluenesulphonate (CTAT)/ sodium chloride micellar solution and in a recent study by Wang et al (2020) with octadecyl trimethyl ammonium chloride (OTAC)/NaSal micellar solution. To characterize the onset of this unsteady motion of the falling sphere, Mohammadigoushki & Muller (2016) and Zhang & Muller (2018) found a criterion by calculating the local extensional Weissenberg number downstream of the sphere based on the local maximum extension rate.…”

Numerical Study on the Unstable Flow Dynamics of Wormlike Micellar Solutions past a Sphere in the Creeping Flow Regime

“…The flows of particle-laden wormlike micellar solutions are widely encountered in industrial processes such as oil recovery, well drilling, personal care products and microfluidics [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The wormlike micelles in these kinds of solutions are large and flexible aggregates formed through spontaneous self-assembly by the amphiphilic surfactant molecules and salts dissolved in the water above a critical concentration [ 9 ].…”

“…A systematic understanding of rheological properties of wormlike micellar solutions in various steady and transient flows is of fundamental interest and is the primary challenge of the research field. Many researchers have been focused on the rheology and flow patterns of these fluids, which exhibit distinct behaviors compared with Newtonian and the generalized Newtonian fluids [ 4 , 5 , 10 , 11 , 12 , 13 , 14 , 15 ]. When particles are dispersed in wormlike micellar solutions, the problem becomes more challenging.…”