The effects of apparent wall slip on rheometric measurements of waxy gels are quantified for gels consisting of a macrocrystalline wax added in mineral oil in concentrations of 3.0 and 7.5 wt. %. The waxy gels are formed in situ in a stress-controlled rheometer, and rheological properties are then obtained. Seven different geometry configurations, including parallel plates, concentric cylinders, and

The rheology and microstructure of soft particle glasses during startup flow are studied using three-dimensional particle dynamics simulations at different particle volume fractions and shear rates. The behavior of transient stress depends on the applied shear rate. At high shear rates, soft particle glasses exhibit a static yield stress signaled by a stress overshoot followed by a relaxation to a

The yield stress behavior of colloidal gels with embedded active particles is studied with three experiments: start-up of steady shear, oscillatory strain amplitude sweep, and creep testing. Activity is generated by Janus particles with a platinum hemisphere; these particles undergo self-diffusiophoretic and self-electrophoretic motion in hydrogen peroxide solutions. The free particle active motion

In some recent experiments on entangled polymers of stress growth in the startup of fast shear flows, an undershoot in the shear stress is observed following the overshoot, i.e., before approaching the steady state. Whereas tumbling of the entangled chain was proposed to be at its origin, here, we investigate another possible cause for the stress undershoot, i.e., slippage at the interface between

We simulate a dense athermal suspension of soft particles sheared between hard walls of a prescribed roughness profile, fully accounting for the fluid mechanics of the solvent between the particles and for the solid mechanics of changes in the particle shapes. We, thus, capture the widely observed rheological phenomenon of wall slip. For imposed stresses below the material’s bulk yield stress, we show

In this work, we introduce a comprehensive machine-learning algorithm, namely, a multifidelity neural network (MFNN) architecture for data-driven constitutive metamodeling of complex fluids. The physics-based neural networks developed here are informed by the underlying rheological constitutive models through the synthetic generation of low-fidelity model-based data points. The performance of these

Viscosity and phase transitions were studied in the (KF-KCl)eut.-(10 mol. %)K2SiF6 system. Synchronous thermal analysis (STA) was used to study the phase transformations in the system in the temperature range of 298–1113 K. The (KF-KCl)eut.-(10 mol. %)K2SiF6 melt was found to be homogeneous at 903–993 K. The viscosity of the system under study was investigated by the rotational viscometer FRS 1600

We study buffered aqueous solutions of deoxyribonucleic acid isolated from bacteriophage lambda (λ-DNA) at shear rates up to 105 s−1. The shear rates are accessed with a narrow-gap rheometer at gap widths down to 20 μm. At lower shear rates, our data merge with the literature values. At high shear rates, the viscosity levels off into an infinite-shear viscosity plateau. Hence, the viscosity functions

Scientific questions surrounding the shear-dependent microstructure of carbon black suspensions are motivated by a desire to predict and control complex rheological and electrical properties encountered under shear. In this work, direct structural measurements over a hierarchy of length scales spanning from nanometers to tens of micrometers are used to determine the microstructural origin of the suspension

Recent studies have shown that rheological material functions that can be linked to structural measures are defined in terms of the recoverable and unrecoverable strains [for example, Lee et al., Phys. Rev. Lett. 122, 248003 (2019)]. In this study, we explore the consequences of applying these ideas to transient nonlinear rheological tests, using new material functions including an elastic modulus

A semi-empirical constitutive equation is suggested for the model comb polymer with the purpose to simultaneously describe the intrinsic medium amplitude oscillatory shear (MAOS) behaviors and transient behaviors in start-up elongational experiments. The molecular stress and hierarchical relaxation of comb polymers are discussed on the basis of the orientation-stretch coupled conformation tensor of

The paraffin molecules in crude oil crystalize and precipitate out as the oil cools, resulting in a sharp increase in oil viscosity and further the gelation of the oil. The waxy crude oil gel exhibits complex rheological behaviors, such as viscoelasticity, yield stress, and thixotropy, posing challenges to the flow assurance of pipelines. Previous studies have verified that applying a high-voltage

ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) of the dissolution processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for

Magnetization AC loss measurements of singe- and seven-core Ba122/Ag tapes have been done by calibration-free method in the range of temperature from 20 K to 42 K and field magnitudes up to 70 mT in RMS with two frequencies 72Hz and 144Hz. A strong effect of eddy current losses in highly conductive Ag sheath was observed for single-core sample, but negligible for seven-core tape with more resistive

Spiral wound heat exchanger has compact structure, good thermal performance per volume and simple manufacture process. It is the key equipment for the superfluid helium cryogenic system, which is able to recover the cold capacity and improve the refrigeration effectiveness. To investigate the influence of fins structure on the thermal performance of spiral wound heat exchanger is essential for its

The cooling systems of High-Temperature Superconducting (HTS) power transmission cables are unable to achieve the desired performance as prescribed in the cryogenic road map. Reverse Brayton cycle based Cryocooler (RBC) has been identified as a refrigerator that has the potential to achieve the desired performance for higher cooling load demand. In this article, an exergy analysis of the basic Reverse

We present some explicit solutions (given in Eulerian coordinates) to the three-dimensional nonlinear water wave problem. The velocity field of some of the solutions exhibits a non-constant vorticity vector. An added bonus of the solutions we find is the possibility of incorporating a variable (in time and space) surface pressure which has a radial structure. A special type of radial structure of the

We consider the large time behavior of the Navier–Stokes flow past a rigid body in \(\mathbb {R}^n\) with \(n\ge 3\). We first construct a small stationary solution possessing the optimal summability at spatial infinity, which is the same as that of the Oseen fundamental solution. When the translational velocity of the body gradually increases and is maintained after a certain finite time, we then

Dissipative solutions have recently been studied as a generalized concept for weak solutions of the complete Euler system. Apparently, these are expectations of suitable measure valued solutions. Motivated from Feireisl et al. (Commun Partial Differ Equ 44(12):1285–1298, 2019), we impose a one-sided Lipschitz bound on velocity component as uniqueness criteria for a weak solution in Besov space \(B^{\alpha

Motivated by an equation arising in magnetohydrodynamics, we address the well-posedness theroy for the non-diffusive magneto-geostrophic equation. Namely, an active scalar equation in which the divergence-free drift velocity is one derivative more singular than the active scalar. In Friedlander and Vicol (Nonlinearity 24(11)::3019–3042, 2011), the authors prove that the non-diffusive equation is ill-posed

The so-called Ladyzhenskaya model is analyzed from a non-autonomous dynamical system point of view, for weak and strong solutions. Existence of attractors when forces are time-dependent is ensured in several universes with different tempered parameter conditions, and also for fixed bounded sets. Attraction is proved in \(L^2\) and \(W^{1,p}\) norms and relationships between these families are also

This paper is dedicated to the design of an artifact-free and geometrically accurate low-diffusive interface capturing method for pure advection problems with extension to the multifluid/multimaterial case. The numerical method involves a genuinely multidimensional gradient limiting process that provides interface reconstruction accuracy without appearance of usually-encountered artifacts like zigzag-shaped

In this work, ePC-SAFT-DGT (i.e., the coupling of ePC-SAFT with the density gradient theory (DGT)) was further developed by modifying the expression for estimating the chemical potential of IL ion-pair and extended to study the interfacial properties of 82 ionic liquids (ILs) containing one of the IL-cations ([Cnmim]+, [Cnpy]+, [Cnmpy]+, [Cnmpyr]+, and [THTDP]+) and one of the IL-anions ([Tf2N]−, [PF6]−

The coefficients of equations for estimating the critical temperatures, pressures, and densities of homologous series with the general formula R1(CH2)nR2 have been calculated using the current experimental database. The equations are based on the hypothesis of functional self-similarity and the scaling behaviour of the critical constants of long-chain molecules (Nikitin et al. Fluid Phase Equilib.

Isobaric-isothermal flash calculations are at the heart of any process calculation. In this paper, we propose two new methods for flash calculations at a specified temperature and pressure. The governing equations derived can not only be solved rapidly but also converge correctly even very close to the critical point with the methods presented in this paper. The derived equations show that simplified

Combined with a high-pressure vibrating-tube densimeter and capillary viscometer, the density and viscosity of CO2(1)+ethyl acetate(2) binary systems with x2 = 0.000, 0.036, 0.075, 0.117, 0.163, and 1.000 were measured under conditions of 308.15-338.15 K and 15-45 MPa. In addition, the volumes of mixing (ΔVm) and viscosity deviation (Δη) were also calculated. The results illustrate that the density

We develop criteria for hitting probabilities of anisotropic Gaussian random fields with associated canonical pseudo-metric given by a class of gauge functions. This yields lower and upper bounds in terms of general notions of capacity and Hausdorff measure, respectively, therefore extending the classical estimates with the Bessel–Riesz capacity and the \(\gamma \)-dimensional Hausdorff measure. We

We present the existence, uniqueness, and regularity of a strong solution to a super-linear stochastic partial differential equation (SPDE) with the random fractional Laplacians: $$\begin{aligned} u_t = a\Delta ^{\alpha /2}u + b u_x + cu + \xi |u|^{1+\lambda } \dot{W},\quad t>0\,;\quad u(0,\cdot ) = u_0(\cdot ), \end{aligned}$$ where \(\dot{W}\) is a space-time white noise, \(\alpha \in (1,2)\), and

ABSTRACT The thermodynamic analysis and preferential solvation of the solubility of sulphanilamide (SA) in five cosolvent mixtures (ethanol + water; 1,4-dioxane + water, acetonitrile + water, dimethyl-sulphoxide + water, and dimethylsulphoxide + water) are presented. The thermodynamic functions are calculated employing the Gibbs and van´t Hoff equations, and the analysis of preferential solvation is

This paper describes the longitudinal dispersion of passive tracer molecules injected in a steady, fully developed, viscous, incompressible, laminar flow through an annular pipe with a first order heterogeneous boundary absorption at the outer wall, numerically using layer-adapted meshes. The model is based on steady advection-diffusion equation with Dirichlet and Robin boundary conditions. The solutions

In this paper, we investigate non-Newtonian Casson fluid flow with pulsation in a channel having symmetrical constriction bumps on the upper and lower walls. The medium is assumed to be porous, following Darcy’s law. The fluid is modeled as electrically low conducting, and the pulsatile flow is subjected to a transverse magnetic field of uniform strength to study the impact of the resulting Lorentz

Recent work modeling the rheological behavior of human blood indicates that it has all the hallmark features of a complex material, including shear-thinning, viscoelastic behavior, a yield stress, and thixotropy. After decades of modeling steady state blood data, and the development of simple steady state models, like the Casson and Herschel-Bulkley the advancement and evolution of blood modeling to

Polyethylene (PE)/silica polymer nanocomposites (PNCs) were investigated mainly using rheological measurements. Various PEs [linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and low-density polyethylene (LDPE)] were selected as polymer matrices, and two comparable particulate silicas were utilized as favorable (hydrophobic, R202) or unfavorable (hydrophilic, A90) fillers.

We suggest a numerical method to calculate molecular weight distribution from linear viscoelastic data. The calculation method consists of three components: (1) a viscoelastic model of a monodisperse polymer as a function of molecular weight; (2) the mixing rule connecting viscoelastic data of monodisperse and polydisperse polymers through molecular weight distribution; (3) an algorithm which calculates

The epidermal mucus secreted by fish is a natural barrier between fish and water, which is a slippery and slightly thick fluid with some biological functions. The present work is to characterize the viscoelastic property of a loach skin mucus published recently by using a viscoelastic model with four hypotheses. The experimental steady shear viscosity with the maximum shear rate of 10 s−1 for the mucus

Isocyanate crosslinkers with blocking agents based on various amine derivatives were newly synthesized for automotive clearcoat applications. Amine-based blocking agents were prepared by varying the alkyl substituent attached on both sides of the main nitrogen atom (named DEA, DiPA, NtBEA, and NtBiA) to modify their deblocking feature in blocked isocyanates (BIs) and curing reaction under thermal curing

The deformation of coal during the injection of sorptive gases can be classified into two types: deformation due to the pore pressure and the swelling deformation of the coal matrix induced by adsorption. These types of deformation have not been investigated separately in the previous researches. The main reason is that measuring the radial strain of the coal core directly and accurately is extremely

Purpose) In this study, for the first time, the efficacy of control rods for full suppression of vortex-induced vibrations (VIV) and galloping of an elastically supported rigid square cylinder that vibrates freely in the cross-flow direction is investigated. Design/methodology/approach To this aim, two small control rods are placed at constant angles of ± 45° relative to the horizontal axis and then

The hydrodynamics and locomotion mechanism of Euglena Gracilis (E. Gracilis) is investigated using microscopic shadow imaging and micro particle image velocimetry (MicroPIV). Three distinct locomotion modes were observed: translation, spin, and left/right turn. Since the flagellum was not possible to image, the strokes were identified by evaluating the flow field around the protist. The flow field

The aim of this study is to identify the flow structure in an airlift pump–bubble generator system by using experimentally obtained differential pressure signals. Differential pressure measurements were applied at both the bottom and top test sections. The normalized time variation of the differential pressure data was analyzed using the probability density function (PDF), power spectral density function

Two-phase data from flashing experiments are presented beyond the traditional time-averaged approach in this work. Probability density functions of parameters such as bubble duration, velocity, chord length, and number frequency are obtained from four-sensor conductivity probes and presented here. The axial evolution of the distributions is discussed in detail along with high-speed videos for a qualitative

The present study aims to reveal gas-liquid flow patterns as gas is injected into co-flowing water. An experimental work was conducted in a loop in which pure water was circulated. The gas-injection nozzle was submerged in the flowing water. Effects of the water flow velocity and gas flow rate were jointly considered. Two-phase flow patterns were visualized using the high-speed photography and then

The evolution of concentrated particle suspensions in a two dimensional channel flow between parallel plates is considered. We developed a numerical model based on the finite volume method to solve the full unsteady Navier Stokes equations coupled to a constitutive advection-diffusion equation in order to determine shear-induced migration phenomenon in concentrated suspensions of monodisperse and non-colloidal

The Rayleigh-Taylor instability (RTI) with a density gradient layer was investigated by implicit large eddy simulations (ILES) in a framework of three dimensional compressible multiphase flow with the single fluid approximation. The simulations are firstly initialized by multi-mode random perturbations in classic RTI and the associated case with a premixed layer. It is found that the late time behaviours

Affordable, high order simulations of turbulent flows on unstructured grids for very high Reynolds’ number flows require wall models for efficiency. However, different wall models have different accuracy and stability properties. Here, we develop a kinetic energy stability estimate to investigate stability of wall model boundary conditions. Using this norm, two wall models are studied, a popular equilibrium

The lattice Boltzmann method has been widely used in curved and moving boundary fluid simulations. Both explicit and implicit treatments are studied to recover proper boundary conditions on Cartesian grids. These methods can describe curved boundaries more accurately and more smoothly than the staircase approximation. However, to improve the order of accuracy and to reduce the fluctuation of force