Top Research Papers on Viscosity

Control of particle motion is generally achieved by applying an external field that acts directly on each particle. Here, we propose a global way to manipulate the motion of a particle by dynamically changing the properties of the fluid in which it is immersed. We exemplify this principle by considering a small particle sinking in an anisotropic fluid whose viscosity depends on the shear axis. In the Stokes regime, the motion of an immersed object is fully determined by the viscosity of the fluid through the mobility matrix, which we explicitly compute for a pushpin-shaped particle. Rather tha...

We derive the equations governing the dynamics of thin viscous sheets having non-homogeneous viscosity, via asymptotic expansion methods. We consider distributions of viscosity that are inhomogeneous in the longitudinal and transverse directions and arbitrary (bulk and surface) external forces. Two specific problems are solved as an illustration. In a first example, we study the effects of purely in-plane variations of viscosity, which lead to thickness modulations when the sheet is stretched or compressed. In a second example, we study a stretched viscous sheet whose viscosity varies both acr...

The invention relates to a novel viscosity reducer for viscous oil, and the novel viscosity reducer is a chemical agent mainly used for viscosity reduction and cold production of viscous oil. The viscosity reducer disclosed by the invention has the advantages of convenience in construction, high viscosity reduction rate, low price and the like. Laboratory tests and field applications show that the viscosity reducer disclosed by the invention is applicable to conventional (borehole) viscosity reduction mining, oil layer viscosity reduction and the like of a viscous oil well and can be used for ...

ABSTRACT Based on the theory that viscous crude oil can form stable two-phase oil-water interfacial molecular membrane with surfactant, the oil-water interfacial activity and viscosity reduction of oil-water interface of viscous crude oil were studied for the ternary compound system, including anionic surfactant alpha olefin sulfonate (AOS), weak alkali Na2CO3 and four different kinds of nonionic surfactant emulsifying silicon oil (LKR-1023), lauryl diethanolamide (LDEA), isomeric alcohol ethoxylates (E-1306), and polyoxyethylene sorbitan monooleate (T-80). Results showed when lipophilic or hy...

Abstract : The effects of volumetric visco-elasticity are investigated for several linear visco-elastic materials under simple loading conditions. In particular, the operators V(D), corresponding to the Poisson ratio of an elastic solid, and the functions V(t) equals - E sub 22 (t)/E sub 11 (t) (where E sub 11 and E sub 22 are the longitudinal and the lateral strains in uniaxial state of stress) are discussed. (Author)

When experiments are made on the viscous flow of pitch and other substances of similar character, in the form of rods or cylinders, by the torsional method, it is found that the rate of turning under torsion of these rods is not strictly proportional to the driving couple. Thus the rate of flow of the material under shearing stress cannot be in simple proportion to stress. If it is wished to investigate the exact law connecting the rate of flow with the shearing forces, by means of the torsional method, a complication is at once met with, arising from the fact that the rate of flow in a twisti...

The viscous Burgers' equation with nonlinear viscosity is considered. The equation is written as a quasilinear parabolic equation in divergence form, and existence of a weak solution is shown. The ...

Abstract The aim of the present study is to investigate the linear and nonlinear wave dynamics of a falling incompressible viscous fluid when the fluid undergoes an effect of odd viscosity. In fact, such an effect arises in classical fluids when the time-reversal symmetry is broken. The motivation to study this dynamics was raised by recent studies (Ganeshan & Abanov, Phys. Rev. Fluids, vol. 2, 2017, p. 094101; Kirkinis & Andreev, J. Fluid Mech., vol. 878, 2019, pp. 169–189) where the odd viscosity coefficient suppresses thermocapillary instability. Here, we explore the linear surface wave and...

We use Velocity Averaging lemma to show that the almost everywhere limit of quasilinear viscous approximations is the unique entropy solution (in the sense of {\it F. Otto}) of the corresponding scalar conservation laws on a bounded domain in $\mathbb{R}^{d}$, where the viscous term is of the form $\varepsilon\,div\left(B(u^{\varepsilon})\nabla u^{\varepsilon}\right)$ and $B\geq 0$.

In this study,a Virial-type viscosity Equation of State(EOS)used for predicting the vis- cosity of the viscous fluid of common refrigerant was established via relating the dimensionless residual viscosity with the reduced density.Adopting this equation,only the critical parameters,molecular weight and eccentric factor of the refrigerant are needed to conduct the calculation.Therefore,on the thermodynamic surface,there is an integrated concordance between the calculation of transport property and that of equilibrium property.According to this new equation,the viscosities of nine common refriger...

Numerical algorithms were developed to solve the basic equations describing growth or dissolution of bubbles in viscous liquids both for isothermal behaviour or variable temperature. Growth and dissolution of gas bubbles in viscous liquids cause changes in concentration inside the bubble and in the liquid at equilibrium with the gas phase, and these changes also affect the dynamics of bubble behaviour. Simple criteria are provided to assess when the role of viscosity is significant, due to slow viscous relaxation. The growth or dissolution of carbon dioxide bubbles and oxygen bubbles in soda-l...

This work examines the breakup of a Stokes thread covered with a monolayer of insoluble surfactant when either surfactants are convected away from the space-time singularity or diffusion is dominant, and provides an analytical expression for thinning rate that explicitly depends on surface rheological parameters.

Soils at critical state are like a visco-plastic fluids, which will flow for applied stresses greater than the critical state (CS) shear strength. Shear viscosity is a key parameter to understand the post-failure flow response of soils in geotechnical applications such as landslides, jacked piles and cone penetrometers. Viscosity of soil has been investigated for water contents greater than the liquid limit because at these water contents standard viscometers can be used. However, soils can reach CS for water contents in the plastic range and thereafter exhibit viscous behavior without further...

In the present study, a flexible pipe has been considered to study the effect of ratio of visco-elastic material viscosity to fluid viscosity on the stability of flexible laminar pipe flow with axi-symmetric disturbances. The effect of thickness of visco-elastic material on the stability of flexible pipe flow with outer rigid shroud has also been studied. The stability curves are drawn for various values of the ratio of visco-elastic material viscosity to fluid viscosity. It is observed that stability of flow is increasing by decreasing the ratio of visco-elastic material viscosity to fluid vi...

Viscosity Viscosity Clear liquid above has lower viscosity than the substance below SI symbol: μ, η SI unit: Pa·s = kg/(s·m) Derivations from other quantities: μ = G·t Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress. In everyday terms (and for fluids only), viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. Put simply, the less viscous the fluid is, the greater its ease of movement (fluidity). [1] Viscosity describes a fluid's in...

The development of surfactants that were used in reducing viscosity of viscous crude oil was reviewed.The application of surfactants in reducing viscosity of viscous crude oil were introduced in which included anionic surfactant,nonionic surfactant,anionic-nonionic amphoteric surfactant and polymeric surfactant,biosurfactant,fluorocarbon surfactant et al.The merits and demerits of these kinds of surfactants were evaluated and the prospect of surfactants used in reducing viscosity of viscous crude oil was brought forward.

Based on dissipation mechanism of shearing power,a new method of modeling dynamic viscosity of polymer melts in vibrating shear flows was proposed in this paper.And theoretical models were formulated.Using the method,the dynamic viscosity of Maxwell fluid in simple vibrating shear flow was found uniform with results using a traditional method.The result uniformity showed validity of the method.And the prediction ability of the method was discussed for vibrating shear flows superposed on steady flow.A deficiency of the model for the superposed flows was found and the causes were analyzed.Finall...

Ultrasonic waveguide sensor for measurement of viscosity of highly viscous fluids has been developed. The measurement principle is based on application of guided shear-horizontal SH0 mode of the Lamb waves propagating in an aluminium planar waveguide immersed in a viscous liquid. Attenuation of the guided wave depends on viscosity of the surrounding liquid and is used for viscosity estimation. The developed sensor is mechanically robust and may be used for in-line process control of viscous liquids.

The research briefly describes various good properties of surfactant and the mechanism of viscosity reduction,the application of its in reducing viscosity of viscous crude oil is also considerable intro- duced

The viscous crude oil from Suizhong 36-1 oilfield with low content of wax,high content of gum and asphaltene,the viscosity of degassed crude oil is 56 200 mPa·s at 40 ℃.With respect to the problem of viscosity-reduction of viscous crude oil recovery,a kind of viscosity reducer comprising styrene/higher alcohol(methyl-)acrylate/acrylamide or maleic anhydride terpolymer was synthesized,and it's ability of viscosity reducing was evaluated.Results show that the synthesized polymer viscosity reducer HOT-RP had good viscosity reduction effect,its viscosity-reducing rate is over 85% at dosage of 500～...

一定の重量を有つた棒が, 容器内にある流體中を自然落下してゆく時の運動方程式を極く近似的に解いて棒の加速度が殆んど0となる附近に於ては, 流體の粘性係數が落下時間と落下距離の自乘との比に比例していることを計算し, これにより種々の温度に對する粘性の比較値を求め, これ等の値が簡單な廻轉法による實驗結果とよく一致することを示した。裝置の設計は極めて簡單で, 手持式にして携帶も可能であろう。若し棒として細い鋼鐵針へ白金鍍金を施したようなものを使用すれば, 各温度毎に新しい棒を用意する必要なくその上裝置全體も極めて小規模なものとなる。ただ精度は理論式の省略程度並びに廻轉法と比較した場合の實驗値の分散等から考えて, Stokes法, 廻轉法よりも劣るようであり (嚴密な比較は未だ行つて居ない) 測定値の誤差に現われてくる種々な因子, 例えば棒と流體容器相互の大きさから來る誤差, 棒が落下する時に流體の表面と底面がこれに及ぼす影響等の詳細な研究も, なおこれを今後に持つ外はない。終りに臨み, 本研究に終始御懇切な御指導, 御鞭韃を賜はつた東京工業大學教授工學博士森谷太郎先生に厚くお禮申上げます。又計算式その他に種々有益な御指示を與えて下さつた, 東京工業大學教授理學博士原島鮮氏に心から感謝致します。最後に實驗を擔當された丸山正男君にお禮申します。

Abstract The results indicate that the hanging-strip method provides good values of η0 under favorable circumstances. The value of the method lies in the convenience and simplicity of the experiment. With little more than a meter stick and a clock, one can estimate zero-shear viscosities which are above 0.1 MPa·s. Careful testing is very important to avoid the effects of molding history and clamping, and to assure that the time-dependence of specimen elongation conforms to the Newtonian liquid model.

Contaminants and other agents are often present at the interface between two fluids, giving rise to rheological properties such as surface shear and dilatational viscosities. The dynamics of viscous drops with interfacial viscosities has attracted greater interest in recent years, due to the influence of surface rheology on deformation and the surrounding flows. We investigate the effects of shear and dilatational viscosities on the electro-deformation of a viscous drop using the Taylor-Melcher leaky dielectric model. We use a large deformation analysis to derive an ordinary differential equat...

According to the properties of viscous crude and using three different kinds of monomers, Aery-late , Styrene and Maleic Anhydride (ASM), a copolymer of oil - soluble viscosity reducers (ASM) has been synthesized . At the same time , the condition of reaction was confirmed, And the paper research the properties of viscosity reducer, the effect of temperature and the viscidity of viscosity reducer compounding with surfactant in viscous crude. Experimental results show that the ASM has better viscosity reduction effect, and has good applied prospects.

We establish the vanishing viscosity limit of viscous Burgers-Vlasov equations for one dimensional kinetic model about interactions between a viscous fluid and dispersed particles by using compensated compactness technique and the evolution of level sets arguments. The limit we obtained is exactly a finite-energy weak solution to the inviscid equations.

HFB, a viscosity reducer by emulsification of viscous crude oil having high salt con- tent, was studied and prepared. The main factors affected the viscosity reducing were discussed. The la-boratory evaluation result indicated that the HFB viscosity reducer obviously reduced the viscosity of theviscous crude oils exploited from three Tahe oil wells, and the viscosity reducing rates were higher than93％.

Normal stresses in sheared suspensions of non-Brownian particles are obtained from numerical simulations in the viscous regime. The stresses are determined in homogeneous shear of non-buoyant particles and by analyzing shear-induced resuspension of buoyant particles in the framework of the suspension balance model (SBM). The consistency of both approaches indicates that the SBM describes the steady state properly. The results are in agreement with some earlier empirical expressions of the normal viscosity coefficients in limited ranges of particle volume fractions, but they appear to overestim...

In this paper we prove the existence of curved, multidimensional viscous shocks and also justify the small‐viscosity limit.

SUMMARY The possibility that slabs of subducted oceanic lithosphere may buckle and fold under longitudinal compressive stresses when they encounter the major seismic discontinuity near a depth of 670 km in the mantle has led us to explore experimentally the behaviour of very viscous plumes falling onto a density interface or a viscosity step. We begin with the case of axisymmetric and planar streams falling through air onto the free surface of a viscous fluid which has the same or smaller density, and observe the conditions under which they coil or fold. In order to remove surface tension and ...

We find Green functions for the accretion disk with fixed outer radius and time-independent viscosity. With the Green functions, a viscous evolution of the disk with any initial conditions can be described. Two types of inner boundary conditions are considered: the zero stress tensor and the zero accretion rate. The variable mass inflow at the outer radius can also be included. The well-known exponential decline of the accretion rate is a part of the solution with the inner zero stress tensor. The solution with the zero central accretion rate is applicable to disks around stars whose magnetosp...

The stability of a thin liquid film bounded by two free surfaces is examined in the presence of insoluble surface active agents. The surface active agents not only cause gradients in surface tension, but could also render surface viscosity to be significant, and variable, as a function of their concentration. A set of three coupled nonlinear evolution equations are derived for the film height, concentration of surface active agents, and the horizontal liquid velocity which governs the dynamics of the free film. Suitable phenomenological models for variation of surface tension and surface visco...

Electric submersible pumps (ESPs) are currently being tested in the service company's newly built viscous lab testing loop; whereby, the viscous performance of each pump stage type is analyzed at multiple speeds and viscosities. This viscous lab testing loop is capable of speeds up to 70 Hz, 30,000 B/D of fluid, with a maximum of 500 HP, and can manage fluid viscosities up to 2,500 cP. Four pumps were tested at speeds ranging from 40 to 70 Hz, in 10 Hz intervals, and up to 2,500 cP fluid viscosity. The viscosity correction factors, for each operating speed and viscosity, were developed for ...

The goal of this work is to show that replacing neural networks with simple grid functions, along with two novel geometric priors achieve comparable results to INRs, with instant inference, and improved training times.

In this paper we assume determination of pseudo-viscosity coefficients of visco-elastic non-Newtonian fluid flow directly near the cooperating micro-bearing surface. We show the constitutive stress-strain dependencies of nonNewtonian visco-elastic media with regard to the content of addition of nano-particles. The greater content of nano-particles and influences of superficial layer of cooperating surfaces on the dynamic oil viscosity, the more distinct non-Newtonian properties. The non-Newtonian properties create non-linear dependencies between strain and stress. Moreover the dynamic viscosit...

The stability of a thin liquid film bounded by two free surfaces is examined in the presence of insoluble surface-active agents. This study is broadly aimed at understanding enhanced stability of emulsions with the increasing surface concentration of surface-active agents. Surface-active agents not only cause gradients in surface tension but could also render surface viscosity to be significant, which could vary with surface concentration. We employ two phenomenological models for surface viscosity, a linear viscosity model and a nonlinear viscosity model. In the latter, surface viscosity dive...

The analysis on the composition and physical characteristics of Liaohe extra-viscous crude oil is made.The results show that the high gum content makes this kind of oil difficult to flow. It is considered that the best way to transport this oil is to develop an oil-soluble viscosity reducing agent to restructure the gum and reduce viscosity efficiently at higher temperature. The trial test on the influence of composition and distribution of molecular weight of viscosity reducing agent on viscosity reducing behavior is made.l,pipelinet

The effects of viscosity stratification and surface tension on Rayleigh-Taylor (RT) instability in a finite thickness layer of an incompressible viscous fluid bounded above by a denser fluid and below by a rigid impermeable surface have been studied using linear stability analysis. A relation for the R T instability growth rate is found by calculating the eigenvalues of the stability equation. It is shown that the shape of the dispersion curve is controlled by the ratio of surface tension to the stress gradient, with the layer thickness and the viscosity stratification affecting the rate of gr...

The shear-induced collective or gradient diffusivity in an emulsion of viscous drops, specifically as a function of viscosity ratio, was computed using a fully resolved numerical method. An initially randomly packed layer of viscous drops spreading due to drop-drop interactions in an imposed shear has been simulated. The collective diffusivity coefficient was computed using a self-similar solution of the drop concentration profile. We also obtained the collective diffusivity (the collective diffusivity coefficient multiplied by the average drop volume fraction), computing the dynamic structure...

We introduce a model of dynamic evolution of a delaminated visco-elastic body with viscous adhesive. We prove the existence of solutions of the corresponding system of PDEs and then study the behavior of such solutions when the data of the problem vary slowly. We prove that a rescaled version of the dynamic evolutions converge to a “local” quasistatic evolution, which is an evolution satisfying an energy inequality and a momentum balance at all times. In the one-dimensional case we give a more detailed description of the limit evolution and we show that it behaves in a very similar way to the ...

Under the different temperature and pressure, the viscosity was measured of the viscous crude oil from the TK427 well supplied by Tahe oilfield and its mixture that the water-cut and gas content are different with high temperature and high pressure viscosimeter. The relationship between the viscosity of the crude oil and its mixture and the temperature or the pressure was discussed with curve-fitting method. It indicates that the viscosity and temperature character fit to exponential law, the viscosity is linear transformation with the pressure. The gas content strongly influences the viscosit...

Nuclear magnetic resonance ( NMR) logging is the only logging for providing information on oil viscosity. The relationship between T_2 and viscosity is established by using NMR measurement with 6 barrels of oil samples, its correlation coefficient is 0.966, based on it NMR logging can be used to estimate oil viscosity. After T_2 changing with temperature is analyzed, fluid properties of viscous reservoirs can be established based the distribution of T_2.

The flow of incompressible viscous fluid is controlled by Navier-Stokes Equations.The qualititave analysis of the solutions of the equation is important to the studies of bifurcation problems and numerical solutions of the equations.In classic theory,it is held that, in Sobolev Space [H 1(Ω)] 3, there is the upper bound of the norm of the constant rotating flow of the incompressible viscous fluid between two closed surfaces. It is inversely proportional to the viscosity of the fluid, and it will go to infinity when the viscosity goes to zero. But in this paper, it is proven that the upper boun...

This paper uses asymptotic methods to analyse the flow in a narrow channel of a fluid with temperature-dependent viscosity and internal viscous dissipation. When the Nahme–Griffith number is large we show how the flow evolves from Poiseuille flow with a uniform temperature distribution to a plug flow with hot boundary layers on the walls. An asymptotic solution is obtained for the flow in the region of transition from Poiseuille to plug flow and an explicit equation is derived for the pressure gradient in terms of the local downstream co-ordinate in this transition region.

Numerical simulations of three-dimensional convection with temperature-dependent viscosity and viscous heating at realistic Rayleigh numbers for Earth's mantle reveal that, in the strongly time-dependent regime, very intense localized heating takes place along the top portion of descending cold sheets and also at locations where the ascending plume heads impinge at the surface.

Viscosities of three associated binary mixtures, viz., chlorobenzene + benzylalcohol, chlorobenzene + n-hexanol and n-hexanol + benzylalcohol have been determined at different temperatures over the complete composition range. Using viscosity-composition-temperature data, excess viscosities and the energies of activation for viscous flow have been obtained and their variations with composition have been discussed. Also, the predicitive abilities of a few of the existing equations for mixture viscosities have been compared.

Abstract The performance of tests with elastic liquids at high shear rates is cumbersome due to viscous dissipation heating, high normal forces, and - above all - edge fracture. This paper shows how such measurements can be improved and simplified over the conventional cone-plate technique by using a partitioned plate. For a polystyrene melt with zero shear viscosity 44.5 kPas at 190˚C, steady state viscosities can be obtained up to 100 s−1. For samples with twice the diameter of the sensing area of the tool, the strain beyond which disturbances can be noticed is about 2 - 3 times higher than ...

The structure and viscosity of low-molecular-weight polybutadiene and polyisoprene mixtures, phase separated by quenching to a temperature inside the coexistence region of the phase diagram, were measured as a function of shear rate and composition.

It INTENDS a reactor device for highly viscous media and flowability, particularly for polymers in the polycondensation of polyesters, ensuring QUALITY REGULAR SOBRESALIENTE reaction product with a relatively simple construction and improved stability against rotation and flexion REACTOR. THE reactor device consists of a housing (1) arranged in a placement that is put into its end an inlet (4) for the inflow of the medium and at the other end an outlet (5) for the reaction products. Within the housing (1) REACTOR DEVICE SUPPORTED rotatably a rotor (8). ACCORDING TO THE INVENTION ROTOR (8) has ...

We consider the evolution of a long and thin vertically aligned axisymmetric viscous thread that is composed of an incompressible fluid. The thread is attached to a solid wall at its upper end, experiences gravity and is pulled at its lower end by a fixed force. As the thread evolves, it experiences either heating or cooling by its environment. The heating affects the evolution of the thread because both the viscosity and surface tension of the thread are assumed to be functions of the temperature. We develop a framework that can deal with threads that have arbitrary initial shape, are non-uni...

The object of this work is to investigate the effect of temperature rise resulting from rotary speed difference between driving and driven plates on the performance of hydro-viscous drive.A simplified mathematic model of the steady and laminar flow between two flat plates was established with consideration of viscosity-temperature characteristics.The numerical solution of temperature,shearing stress and viscous torque were obtained by using computational fluid dynamics(CFD) code FLUENT.Then,an experiment rig was designed and developed for this work.The numerical and experimental results show t...