Temperature Dependence Of Viscosity Research Articles

Influence of Fly Ash on the Fluidity of Blast Furnace Slag for the Preparation of Slag Wool

Using fly ash as the modifier, blast furnace slag was modified to prepare slag wool, fulfilling the goal of using one type of waste to make use of another type of waste, and it is of great significance for the comprehensive utilization of industrial bulk solid wastes and resource recycling. In the process of forming fiber from blast furnace slag, fluidity is the key factor affecting the smooth formation of fiber from slag. To explore the changes in the fluidity of modified blast furnace slag, the temperature-dependent viscosity of modified blast furnace slag with different amounts of fly ash added was measured, and the effects of fly ash addition on the viscosity, fluidity, and activation energy of particle migration, and slag structure of modified blast furnace slag were investigated. The results indicated that with the increase in the amount of fly ash added, in the high-temperature region (>1324 °C), the viscosity of modified blast furnace slag increases gradually, the fluidity decreases gradually (i.e., the fluidity becomes worse), and the suitable fiber-forming temperature range gradually widens. When the fly ash addition increases from 5% to 25%, the trend of the activation energy of slag particle migration is as follows: increase, decrease, increase significantly, decrease. When the addition of fly ash is less than 20%, the SiO2 content and slag temperature jointly affect the breakage and reorganization of oxygen bridge bonding in the silicon-oxygen tetrahedron in the slag structure. When the addition of fly ash increases to 25%, the slag temperature dominates the breakage of oxygen bridge bonding in the silicon-oxygen tetrahedron in the slag structure. When using fly ash as the modifier to prepare slag wool, from the perspective of slag fluidity and process operability, the optimum addition amount of fly ash is 15%.

Magnetohydrodynamic hybrid nanofluid flow over a decelerating rotating disk with Soret and Dufour effects

PurposeThe investigation of fluid flow over a rotating disk has been increasing due to the spread of machine technology. Because of this development, we scrutinized the Magnetohydrodynamic (MHD) flow of hybrid nanofluid caused by a decelerating rotating disk with Ohmic heating, Soret and Dufour effects. The disk's angular velocity is taken to be an inversely time-dependent linear function. Moreover, the temperature-dependent viscosity of hybrid nanofluid is incorporated in the present investigation. Methanol is considered as base fluid, while copper oxide (CuO) and magnesium oxide (MgO) are nanoparticles.Design/methodology/approachEstimated fundamental partial differential equations of flow problems are altered as a dimensionless system of ordinary differential equations using appropriate similarity transformation and solved using a numerical technique: BVP Midrich scheme in Maple software. The impression of emerging non-dimensional parameters is portrayed graphically. All outcomes are shown in the velocity, temperature and concentration profiles.FindingsThe developed flow problem involves a non-dimensional parameter (A) that reveals the deceleration of the disk. For larger values of A, the disk decelerates faster and for some fixed time, the fluid surrounding the disk revolves more rapidly than the disk itself. The radial velocity of fluid diminishes and axial velocity becomes uniform when the disk is subjected to wall suction velocity (B).Originality/valueThis analysis is significant in biomedical engineering, cancer therapeutic, manufacturing industries and nano-drug suspension in pharmaceuticals. The novelty of the current study is the hybrid nanofluid flow with Ohmic heating, Soret and Dufour effects on a decelerating rotating disk. To the best of the author's knowledge, no such consideration has been published in the literature.

Study of the influence of temperature dependent viscosity on fluid flow in annular channels

For all liquids, a change in viscosity depending on temperature is characteristic. In most cases, this dependency is commonly overlooked; however, when studying the flow of liquids under conditions of intense heat exchange, the temperature-dependent viscosity can have a significant impact on mass and heat transfer processes. It should be noted that for some liquids, such as polymer solutions or biological fluids, the temperature dependence of viscosity can be extremely complex and nonlinear. In such cases, ignoring this dependence can lead to inaccurate results and errors. Annular channels find wide applications in various technical systems, including heat exchangers and hydraulic devices. Understanding the factors influencing the fluid flow and discharge in such channels is a key aspect of optimizing their design and operation. One of the main factors influencing the flow process and fluid discharge in annular channels is the temperature-dependent viscosity of the fluid. This work investigates the influence of the thermo-viscous parameter with monotonic and non-monotonic temperature-dependent viscosity, as well as the geometric parameter of the annular channel on the fluid flow process and discharge. The mathematical model includes the continuity equation, Navier-Stokes equations, and the temperature equation. The method of control volume and the SIMPLE algorithm, modified to account for the variable viscosity coefficient, were applied for the numerical solution of these equations. It is shown that in the case of liquid flow in an annular channel with a monotonic dependence of viscosity on temperature, the steady-state discharge closely approaches the discharge at maximum viscosity. However, in the case of a liquid with non-monotonic viscosity dependence on temperature, the discharge significantly depends on the thermo-viscous parameter.

Approximate Analytical Study of Natural Convection Flow of Non-newtonian Fluid Through Parallel-Pates With Heat Generation

In this present paper, approximate analytical study of natural convection flow of non-Newtonian fluid through Parallel-plates with heat generation is considered. The coupled non-linear momentum and energy equations was solved using perturbation technique. The cases of constant viscosity and temperaturedependent viscosity are treated with the case of temperature-dependent viscosity considered in two models: Reynold's model and Vogel's model. Within the constant viscosity case, results show that increase in the non-Newtonian parametersß, M, decreases the velocity of the fluid flow and increase in these parameters enhances the temperature of the plates. The effects of non-Newtonian and viscosity indices of both Reynold's and Vogel's models on velocity and temperature profiles are presented.

Mathematical modeling of a three-component system to investigate the formation and characteristics of glass

The article investigates glass formation and its properties in a three-component system using mathematical modeling. The authors have applied the method of mathematical planning to increase the efficiency of research and to establish the dependences of glass properties on the composition. The authors propose a mathematical model of structure relaxation and two-dimensional stress field in grade glass products, considering the temperature dependencies of glass viscosity of a given chemical composition.

Elucidation of Correlation between Molecular Structure and Viscosity by Measuring Temperature Dependence of Dielectric Relaxation Spectra and Shear Viscosity

Elucidation of Correlation between Molecular Structure and Viscosity by Measuring Temperature Dependence of Dielectric Relaxation Spectra and Shear Viscosity

A Maxwell relation for dynamical timescales with application to the pressure and temperature dependence of water self-diffusion and shear viscosity.

A Maxwell relation for a reaction rate constant (or other dynamical timescale) obtained under constant pressure, p, and temperature, T, is introduced and discussed. Examination of this relationship in the context of fluctuation theory provides insight into the p and T dependence of the timescale and the underlying molecular origins. This Maxwell relation motivates a suggestion for the general form of the timescale as a function of pressure and temperature. This is illustrated by accurately fitting simulation results and existing experimental data on the self-diffusion coefficient and shear viscosity of liquid water. A key advantage of this approach is that each fitting parameter is physically meaningful.

Temperature-dependent anomalous viscosity of aqueous solutions of imidazolium-based ionic liquids.

Ionic liquids (ILs) are organic salts with a low melting point compared to inorganic salts. Room temperature ILs are of great importance for their widespread potential industrial applications. The viscosity of aqueous solutions of two imidazolium-based ILs, investigated in the present study, exhibits an anomalous temperature variation. Unlike conventional molecular fluids, the viscosity of 1-methyl-3-octyl imidazolium chloride [OMIM Cl] and 1-methyl-3-decyl imidazolium chloride [DMIM Cl] solutions is found to increase with temperature and then depress. The Small Angle X-ray Scattering (SAXS) data suggest that the lattice parameter of the body-centered cubic lattice formed by the spherical micelles of these ILs, and the morphology of the micelles remain intact over the measured temperature range. The molecular dynamics simulation shows the micelles to be more refined with their integrated structure on increasing the temperature. On further increase of the temperature, the structure is found to be loosened, which is corroborated by the simulation work. The ionic conductivity of these IL solutions shows a trend that is opposite to that of the viscosity. The observed anomalous nature of the viscosity is attributed to the trapped dissociated ions in the network of the micellar aggregates.

Залежність «в’язкість – температура» вбирних олив різних виробників.

Coal tar wash oil is the main absorbent for removing benzene hydrocarbons from coke gas and is also used in various industries. Determination of oil viscosity is important primarily for precise regulation of the flow of the substance, given that a low viscosity value indicates less resistance to movement and higher movement speed. The value of the oil viscosity index in the process of its use for the recovery of benzene hydrocarbons from coke gas acquires the status of an integral criterion for evaluating the properties of the oil as an absorbent. For engineering and technological calculations of the viscosity of wash oil, coke chemists of Ukraine use two reference sources of information, although the conditions and materials for obtaining data are not specified in these sources. In the current period in Ukraine, in connection with the limitation of the production of wash oil, the issue of purchasing foreign samples of oil of a wide range of quality is being considered. To determine and interpret the temperature dependence of viscosity for samples of foreign and domestic oils of different composition, experiments were performed to measure dynamic viscosity using a Brookfield DV2T rotational rheometer with a controlled shear rate. β-methyl naphthalene was selected as the additive that most reduces oil viscosity, and diphenylene oxide as the additive that most increases oil viscosity. Among the experimentally obtained dependences, the maximum viscosity values are obtained by the oil produced in Ukraine on a single-column unit, and the minimum values by the oil produced abroad, artificially saturated with β-methyl naphthalene. The nature of the experimentally obtained curves is approximately the same, only the heavier domestic oil is more temperature-dependent at the beginning of the temperature range taken for research. Foreign samples of absorbent oil with a rather narrow boiling range have a lower viscosity level than oils of Ukrainian producers with a wider boiling range. Keywords: wash oil, viscosity, temperature dependence, aromatic components, viscous flow activation energy. Corresponding author: Artem L. Bannikov, e-mail: artiksmartik@gmail.com

Numerical approximation of convective Brinkman-Forchheimer flow with variable permeability

This paper investigates the nonlinear dispersion of a pollutant in a non-isothermal incompressible flow of a temperature-dependent viscosity fluid in a rectangular channel filled with porous materials. The Brinkman-Forch-heimer effects are incorporated and the fluid is assumed to be variably permeable through the porous channel. External pollutant injection, heat sources and nonlinear radiative heat flux of the Rossland approximation are accounted for. The nonlinear system of partial differential equations governing the velocity, temperature and pollutant concentration is presented in non-dimensional form. A convergent numerical algorithm is formulated using an upwind scheme for the convective part and a conservative-type central scheme for the diffusion parts. The convergence of the scheme is discussed and verified by numerical experiments both in the presence and absence of suction. The scheme is then used to investigate the flow and transport in the channel. The results show that the velocity decreases with increasing suction and Forchheimer parameters, but it increases with increasing porosity.

Improve heat transfer in sudden expansion canal by using obstacle

The purpose of this investigation is to determine if adding an isolated cylinder to the domain can improve forced convection in the laminar case of the sudden expansion flow in a two-dimensional channel. The range of the Reynolds number (1-200) and the number of prattle 0.71, the impact of different cross-stream locations (x=10.4,10.8 and 11.2) of the circular cylinder on the flow, and thermal properties of the sudden expansion flow have been computationally studied (air). COMSOL Multiphysics is utilized to address the governing continuity, Navier-Stokes, energy equation of energy, and the necessary boundary conditions. Although streamline and isotherm profiles have been used to describe the flow and thermal fields, the temperature dependence of the flow viscosity and thermal conductivity has not been taken into account. The findings presented here demonstrate an improvement in the peak Nusselt value when a circular cylinder is used in comparison to the unobstructed condition.

Dynamic viscosity of hydrocarbons and ionic liquids at high-temperature

In this work, dynamic viscosities of hydrocarbons and ionic liquids are studied. At high temperatures in these materials, a decrease in the value of dynamic viscosity was observed. Intermolecular interactions in the objects of study have been studied. It has been established that the intermolecular interaction in hydrocarbons is determined by the Born potential ([Formula: see text]. In this case, the temperature dependence of the dynamic viscosity of hydrocarbons is described by the law [Formula: see text]. It has been established that the dynamic viscosity of hydrocarbons in liquid form has a non-activating character. This occurs directly due to momentum transfer by phonons between adjacent layers located at a distance of nanometers.

ЗАЩИТНАЯ ЭФФЕКТИВНОСТЬ МАСЛЯНЫХ КОМПОЗИЦИЙ С ПАРАФИНОМ

The effectiveness of compositions based on fresh M10G2k and used motor oil (MMO) with the addition of paraffin 1-10 wt. % for the protection of carbon steel was investigated in this work. Preservative compositions were prepared by dissolving paraffin in oils with heating. The protective coating on the metal was formed during the day. Kinematic viscosity was measured by the Brookfield method on a rotational viscometer. Studies have shown that paraffin has a thickening effect. Empirical equations were obtained, which are a special case of the Reynolds-Filonov equation, describing the viscosity-temperature dependences for compositions based on fresh and used engine oil and paraffin with a high reliability of linear approximation in the temperature range of 20 - 60 0C. The resulting equations make it possible to determine the kinematic viscosity of the compositions at various paraffin concentrations in a given temperature range. Electrochemical studies have shown that the introduction of paraffin increases the protective effectiveness of both fresh and used engine oil. The protective effectiveness of compositions based on used engine oil is higher. With an increase in the concentration of paraffin, the protective effectiveness of the compositions increases. The best results were obtained for compositions of 10 wt. % paraffin in MMO. Gravimetric studies confirmed the obtained results. Some discrepancies in the values obtained by gravimetric and electrochemical methods are explained by the different duration of the experiments.

Rheology of Conductive High Reactivity Carbonaceous Material (HRCM)-Based Ink Suspensions: Dependence on Concentration and Temperature.

The present case study reports a shear rheological characterization in the temperature domain of inks and pastes loaded with conductive High Reactivity Carbonaceous Material (HRCM) consisting mainly of few-layers graphene sheets. The combined effect of filler concentration and applied shear rate is investigated in terms of the shear viscosity response as a function of testing temperature. The non-Newtonian features of shear flow ramps at constant temperature are reported to depend on both the HRCM load and the testing temperature. Moreover, temperature ramps at a constant shear rate reveal a different viscosity-temperature dependence from what is observed in shear flow ramps while maintaining the same filler concentration. An apparent departure from the well-known Vogel-Fulcher-Tamman relationship as a function of the applied shear rate is also reported.

Mathematical modelling and analysis of thermoregulation effects on blood viscosity under magnetic effects and thermal radiation in a permeable stretching capillary

The current study deals with the mathematical modelling and analysis of the effects of thermoregulation on blood viscosity under magnetic and thermal radiation effects on a permeable, stretching blood capillary. The model comprises the governing equations of the resulting boundary layer problem, which is a set of nonlinear partial differential equations, and this is transformed into a coupled system of nonlinear differential equations using similarity transformation. The numerical solution of the problem is attained by the fourth-order Runge Kutta method with the shooting method. The current work examines the velocity and temperature profile of blood flow with the impact of varying temperature-dependent blood viscosity, involving the variation of several physical parameters such as magnetic field, radiation parameter, permeability parameter, Prandtl number, and surface temperature, as well as their physical interpretation. During certain therapies, the thermoregulation mechanism in humans causes a change in blood flow behaviour. Also, blood flow must be regulated during pathological conditions with the help of radiation, heat, or magnetic effects. It is found that, due to the varying viscosity parameter, the magnetic field effect inhibits heat transport in the body. It has also been found that increasing the permeability parameter enhances mass and heat transfer. The results of this paper could be important in analysing and regulating blood flow and body temperature during hypothermia and hyperthermia therapies.

Bayesian approach to the tomographic problem with constraints from geodynamic modeling: Application to a synthetic subduction zone

Geodynamic tomography, an imaging technique that incorporates constraints from geodynamics and mineral physics to restrict the potential number of candidate seismic models down to a subset consistent with geodynamic predictions, is applied to a thermal subduction model. The goal is to test the ability of geodynamic tomography to recover structures harbouring complex deformation patterns. The subduction zone is parameterised in terms of four unknown parameters namely the slab length L, thickness R, temperature Tc, and dip angle θ that define its thermal structure. A temperature-dependent viscosity is then prescribed with an activation coefficient E controlling the sensitivity. Using the full forward approach to geodynamic tomography, we generate anisotropic surface wave dispersion measurements as synthetic data. We then attempt to retrieve the five unknown parameters by inverting the synthetics corrupted with random uncorrelated noise. The final output is an ensemble of models of L, R, θ, Tc and E cast in terms of a posterior probability distribution and their uncertainty limits. Results show that the parameters are tightly constrained with the apparent existence of a single misfit minima in each of them, which implies the implicit retrieval of the complete patterns of upper mantle deformation, and correspondingly, the 21-independent coefficients defining elastic anisotropy. Each model realisation however fails to swarm around its true value. Such results are attributed to the inability of the surrogate model to accurately replicate the correct forward model for computing anisotropy due to the inherent complexity of the deformation patterns considered. Nevertheless, this proof of concept shows a self-consistent method that incorporates mantle flow modeling in a seismic inversion scheme.

Particle swarm optimization based numerical study for pressure, flow, and heat transfer over a rotating disk with temperature dependent nanofluid properties

In the era of nanotechnology and advanced manufacturing, many industrial applications involve the flow control over the rotating disk. Rotating machineries, computer storage devices, dynamic filtration processes, gas turbine engines, bio inspired electro-catalysis processes are a few of them. Considering the wide applications of flow over rotating permeable disks, this paper presents the investigation of flow, temperature and pressure characteristics of water-based titanium oxide nanofluid with temperature dependent properties. The quadratic Boussinesq approximation is considered to incorporate the density variations due to temperature change. The numerical computation is carried out using metaheuristic based hybrid shooting technique. Temperature dependent dynamic viscosity and thermal conductivity models for nanofluid are considered and the numerical results for velocity components, pressure and temperature distributions are investigated. The investigation unveiled reduction in skin friction and heat transfer rate with increasing value of quadratic convection parameter. The suction parameter is found to be very significant in terms of increasing heat transfer rates. An 80% increase in local Nusselt number is observed for a small change in suction parameter from −1 to −1.5.

On lower-dimensional models of thin film flow, Part C: Derivation of a Reynolds type of equation for fluids with temperature and pressure dependent viscosity

This paper constitutes the third part of a series of works on lower-dimensional models in lubrication. In Part A, it was shown that implicit constitutive theory must be used in the modelling of incompressible fluids with pressure-dependent viscosity and that it is not possible to obtain a lower-dimensional model for the pressure just by letting the film thickness go to zero, as in the proof of the classical Reynolds equation. In Part B, a new method for deriving lower-dimensional models of thin-film flow of fluids with pressure-dependent viscosity was presented. Here, in Part C, we also incorporate the energy equation so as to include fluids with both temperature and pressure dependent viscosity. By asymptotic analysis of this system, as the film thickness goes to zero, we derive a simplified model of the flow. We also carry out an asymptotic analysis of the boundary condition, in the case where the normal stress is specified on one part of the boundary and the velocity on the remaining part.

Unsteady axisymmetric flow of nanofluid on nonlinearly expanding surface with variable fluid properties

The physical phenomena of nanofluid at high temperature motivate us to analyze problems with temperature-reliant fluid properties, like viscosity and thermal conductivity. Since in glass blowing, viscosity and thermal conductivity of the fluid may gets affected in such high temperature. This communication deals with the unsteady flow of nanofluid generated by nonlinear expansion of the surface. Temperature-dependent fluid viscosity and thermal conductivity are considered in the investigation of the problem. The flow of nanofluid is modeled using famous the Buongiorno's two-phase model, which includes the simultaneous effect of Brownian motion and thermophoresis diffusion. Appropriate transformations are adopted to obtain the ODEs from governing PDEs. Then MATLAB ‘bvp4c’ computation is used to solve the problem and to get a clear insight of the influences of various parameters. Graphical comparisons are made to check the accuracy of used numerical method. The study explores that heat transfer rate significantly enhances by the index of nonlinearity, variable viscosity and thermal conductivity parameters. Unsteadiness of the flow can be used as a controlling parameter to reduce the surface drag, heat and nano-mass transfer rate. Variable viscosity parameter leads to enhance the velocity near the surface and reducing the concentration of the nanoparticles. The thermal and concentration boundary layer thickens with thermal conductivity parameters. Nanofluid temperature and concentration of nanoparticles decay with nonlinear expanding index.

Computational study of temperature and density perturbations on atmospheric dynamics

This study examines the perturbation effect of temperature and density of moist air on atmospheric variables at 9°1’48″N, 38°44’24″E and 6.324 km above the Earth’s surface. The atmosphere is a compressible neutral moist air flowing on a rotating Earth as a model and it’s basic atmospheric parameters such as gas constant, transport coefficients, mixing ratio and specific heat capacities are considered to be temperature dependent and the Earth’s gravity changes with latitude and altitude. To describe the dynamics, we carried out a numerical computation using finite difference method on an unstaggered grid. Our results revealed that the response of all the variables have a plane wave pattern, in which specific heat capacities (SHCs), resultant wind speed (RWS) and water vapor mixing ratio (MR) increase with time at each latitude but vertical wind speed (VWS), specific enthalpy (SE) and pressure decrease with time at each latitude. The increase of MR with time is the result of water vapor flux into the air parcel and the decrease of SE and increase of RWS with time is the result of thermal energy to mechanical energy transformation. The decrease of VWS with time is the effect of the viscous force due to temperature dependence of viscosity.