相关论文: Simultaneous measurement of extensional stress and…
The present study proposes a novel full-field extensional rheo-optical technique to investigate the relationship between the rheological properties and internal structural deformation of complex fluids under uniaxial extensional flow.…
The viscoelastic behavior of liquid polymers changes depending on the microstructure of the polymer chains. To investigate the unsteady structural changes induced by polymer chain morphology under stress, we develop a simple rheo-optical…
In this study, the concept of rheo-optics is applied that explores the flow birefringence caused by stress components along the optical axis of the camera since it is often overlooked in the traditional theories of photoelastic flow…
This study investigates the relationship between phase retardation and strain rates in combined extensional-shear flows using the Jeffery-Hamel flow formalism, which yields an analytical velocity solution. Flow birefringence was measured in…
The present study investigated the flow birefringence induced by shear components along a camera's optical axis, which has been neglected in conventional theories of photoelastic measurements. Measurements were conducted for a wide range of…
In Part I of this paper [Haward et al. submitted (2023)], we presented a new three-dimensional microfluidic device (the optimized uniaxial and biaxial extensional rheometer, OUBER) for generating near-homogeneous uniaxial and biaxial…
We present a new design for a confocal rheoscope that enables uniform uniaxial or biaxial shear. The design consists of two precisely-positioned parallel plates with a gap that can be adjusted down to 2$\pm$0.1 \mu m, allowing for the…
Flow birefringence measurement is an emerging technique for visualizing stress fields in fluid flows. This study investigates flow birefringence in the steady radial Hele-Shaw flow. In the radial Hele-Shaw flow, stress is dominant along the…
We present a numerical optimization of a "6-arm cross-slot" device, yielding several three-dimensional shapes of fluidic channels designed to impose close approximations to ideal uniaxial (or biaxial) stagnation point extensional flow under…
This study systematically investigates the flow birefringence of cellulose nanocrystal (CNC) suspensions. The aim is to clarify the importance of the stress component along the camera's optical axis in the stress-optic law (SOL), which…
We investigate the flow evolution of a linear and a branched wormlike micellar solution with matched rheology in a Taylor-Couette (TC) cell using a combination of particle-tracking velocimetry, birefringence, and turbidity measurements.…
We investigate the steady-state extensional viscosity of wormlike micellar solutions using dissipative particle dynamics simulations. As the extension rate increases, the steady-state extensional viscosity initially increases and…
A particle moving through a worm-like micellar fluid (WLM) shows instability and large fluctuations beyond a threshold \textcolor{black}{velocity/force (depending on the control parameter used)}. Despite many detailed studies, a direct…
Several surfactant molecules self-assemble in solution to form long, cylindrical, flexible wormlike micelles. These micelles can be entangled with each other leading to viscoelastic phases. The rheological properties of such phases are very…
Based upon mesoscale simulations of binary mixtures with very low surface tension and positive disjoining pressure (frustration), we measure the correlation length of the stress field within the flowing mixture, as a function of the…
We study theoretically the formation of shear bands in time-dependent flows of polymeric and wormlike micellar surfactant fluids, focussing on the protocols of step shear stress, step shear strain (or in practice a rapid strain ramp), and…
An extended volume of fluid method is developed for two-phase direct numerical simulations of systems with one viscoelastic and one Newtonian phase. A complete set of governing equations is derived by conditional volume-averaging of the…
When a drop of fluid hits a small solid target of comparable size, it expands radially until reaching a maximum diameter and subsequently recedes. In this work, we show that the expansion process of liquid sheets is controlled by a…
In this study, we experimentally investigate the stress field around a bubble rising in a dilute surfactant solution (20 < Re < 220, high Peclet numbers) whose surface gradually becomes contaminated, and compare it with that around a sphere…
Here we present an experimentally practical and robust method to compute the transient extensional viscosity from exponential shear on a wide variety of viscoelastic complex fluids. To achieve this, we derive an analytical, frame-invariant…