In this paper, we report a detailed experimental investigation of sedimentation sphere through wormlike micellar fluids by combination rheometry, particle tracking velocimetry, and image velocimetry techniques. Beyond critical threshold, never reaches terminal velocity instead exhibits oscillatory motion in the axial direction similar to previous reports [Jayaraman Belmonte, Phys. Rev. E 67, 065301R (2003); Chen Rothstein, J. Non-Newtonian Fluid Mech. 116, 205–234 (2004)]. Although...

Monoclonal antibodies (mAb) represent an important class of biologic therapeutics that can treat a variety diseases including cancer, autoimmune disorders or respiratory conditions (e.g. COVID-19). However, throughout their development, mAb are exposed to air-water oil-water interfaces may trigger partial unfolding lead the formation proteinaceous aggregates. Using combination dynamic surface tensiometry and spatially resolved 1D 1H NMR spectroscopy, this study investigates if adsorption...

In this study, we experimentally investigate the rheological and flow behavior of two-dimensional (2D) monodisperse aqueous foams, sheared between parallel plates using a custom-made rheo-optical apparatus with smooth roughened walls. The foams were prepared two commercially available detergents, Foam 1 Foam2, while maintaining similar bubble sizes liquid fractions. linear viscoelastic results reveal that consistently exhibits higher elastic loss moduli than 2, regardless boundary...

Diffusion studies using nuclear magnetic resonance (NMR) spectroscopy were conducted on two model surfactant solutions of cetyltrimethylammonium bromide/sodium salicylate (CTAB/NaSal) and cetylpyridinium chloride/sodium (CPCl/NaSal). By increasing the salt-to-surfactant concentration ratio, these systems display peaks in zero-shear viscosity relaxation time, which are indicative transitions from linear to branched micellar networks. The goal this work is assess sensitivity NMR diffusometry...

We report experiments on the flow of wormlike micellar solutions based cetylpyridinium chloride/sodium salicylate past a falling sphere via combination particle tracking velocimetry, image rheology, and induced birefringence (FIB). Recent studies have shown that beyond critical extensional Deborah number, in micelles never reaches constant terminal velocity; instead, it settles with an unsteady velocity. This behavior is linked to chain scission wake sphere. Similar instabilities...

We report experiments on two series of wormlike micellar solutions that comprise octyl trimethylammonium bromide/sodium oleate (OTAB/NaOA) and cetylpyridinium chloride/sodium salicylate (CPCl/NaSal) using a capillary breakup extensional rheometer (CaBER) dripping onto substrate (DoS) technique. These systems show peak in zero shear viscosity or the relaxation time beyond critical surfactant salt concentration. Prior cryogenic transmission electron microscopy imaging has indicated system...

In this paper we investigate the flow of a shear banding wormlike micellar fluid based on cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal). The is studied in custom-built Taylor-Couette (TC) cell via combination particle tracking velocimetry situ rheology. spatiotemporal evolution velocity profile across rheometer gap tracked after an imposed step rate. range rates mixture shows behavior, that distinct differing rate profiles gap. As bands form temporally, elastic recoil...

We report three stages for locomotion of a helical swimmer in yield stress fluids. In the first stage, must overcome material's strain to generate rotational motion. However, exceeding threshold is not sufficient locomotion. Only when viscous forces are sufficiently strong plastically deform material finite distance away from will net occur. Once underway third retards swimming at small pitch angles. Conversely, large angles, dominates flow by enhancing speed. Flow visualizations reveal...

Branched micelles show stronger birefringence than linear in flow.

Abstract The morphology development of polypropylene (PP)/polyethylene terephthalate (PET)/styrene‐ethylene‐butylene‐styrene (SEBS) ternary blends and their fibers were studied by means scanning electron microscopy (SEM) in conjunction with the melt linear viscoelastic measurements. was also predicted using Harkin's spreading coefficient approach. samples varying composition PP as major phase PET SEBS minor phases considered. Although SEM binary showed matrix‐dispersed type morphology, blend...

Measuring the surface tension of yield stress fluids has remained a critical challenge due to limitations traditional tensiometry techniques. Here, we overcome those limits and successfully measure mechanical properties model fluid based on Carbopol gels via needle-induced cavitation (NIC) technique. Our results indicate that is approximately 70 ± 3 mN/m, independent rheology over wide range values σy = 0.5-120 Pa. In addition, demonstrate Young modulus smaller than E < 1 kPa can be measured...

Flow transitions in wormlike micelle solutions flowing around a microfluidic 90\ifmmode^\circ\else\textdegree\fi{} bend are studied. Shear-banding properties of the solution correlate with form secondary flow, while morphology (linear vs branched) has little effect on flow behavior.

We investigate the effects of helical swimmer shape (i.e. pitch angle and tail thickness) on swimming dynamics in a constant viscosity viscoelastic (Boger) fluid via combination particle tracking velocimetry, image velocimetry three-dimensional simulations finitely extensible nonlinear elastic model with Peterlin approximation (FENE-P). The 3D-printed is actuated magnetic field using custom-built rotating Helmholtz coil. Our results indicate that increasing thickness enhances normalized...

We investigate the flow evolution of a linear and branched wormlike micellar solution with matched rheology in Taylor–Couette (TC) cell using combination particle-tracking velocimetry, birefringence, turbidity measurements.

We report experiments on simple shear of a monolayer bidisperse and polydisperse bubbles in Couette device. The segregate according to their sizes, with larger ones the middle gap smaller closer walls, when rate bubble size ratio are each above threshold. spatial distribution becomes flatter across as its area fraction increases. To explain these observations, we adapt model for monodisperse emulsions that predicts droplets an outcome competition between migration away from walls...

We report experiments on lateral migration of bubbles in a two-dimensional foam sheared narrow-gap Couette device. A larger bubble an otherwise monodisperse raft migrates toward the center gap as long size ratio and shear rate are each above threshold. The speed is roughly two orders magnitude higher than that single bubble, increases with ratio. also deforms much more isolated one at same rate. Modifying Chan-Leal solution for submerged or drop, we derive formula successfully predicts all...

Formation of an unusually extended wake behind a falling sphere in shear thickening dilute micellar solution (CTAB/5mS) is reported. It suggested that this behavior linked to flow-induced structure formation where micelles transition from rodlike wormlike around the sphere.

We report an experimental study on shearing a monolayer of monodisperse bubbles floating liquid in narrow-gap Couette device. The such ``bubble raft'' coalesce only if the shear rate exceeds threshold value. This is contrast to conventional wisdom that and drops for gentler collisions, at rates below critical Furthermore, increases with bubble size viscosity suspending liquid, contravening reasoning based capillary number. Through visualization scaling arguments, we investigate several...

The morphology development and melt linear viscoelastic properties of PA6/PP/PS (70/15/15) ternary blends were studied. An attempt was also made to predict the these using dynamic interfacial tension blend components evaluated from Palierne's model in conjunction with spreading coefficient approach. samples prepared by blending an internal mixer at temperature 260°C rotor speed 60 rpm. exhibited a pronounced low-frequency nonterminal storage modulus whose values much greater than those...

An axisymmetric squirmer in a Bingham viscoplastic fluid is studied numerically to determine the effect of yield stress environment on locomotion. The nonlinearity governing equations necessitates numerical methods, which accomplished by solving variable-viscosity Stokes equation with Finite Element approach. effects stroke modes, both pure and combined, are investigated it found that for treadmill or "neutral" mode, swimmer has lower swimming velocity uses more power. However, efficiency...