Increase In Viscosity Parameter Research Articles

Influence of exponential heat source, variable viscosity and shape factor on a hybrid nanofluid flow over a flat plate when thermal radiation and chemical reaction are significant

The significance of hybrid nanofluid flow over a flat plate lies in its ability to enhance heat transfer, improve energy efficiency, enable temperature control, and provide surface protection. For instance, hybrid nanofluids can provide a protective coating on the surface of a flat plate due to the presence of nanoparticles. This coating can offer improved corrosion resistance, erosion resistance, and anti-fouling properties. Consequently, it can extend the lifespan of the flat plate and reduce maintenance requirements. In this study, we examined how several characteristics, such as variable viscosity, chemical reaction, thermal radiation and shape factor of nanoparticles, affect the flow of a hybrid nanofluid (H[Formula: see text]) through a flat plate. The equations required to represent the problem have been turned into a system of nonlinear ordinary differential equations, and this system has been unraveled by means of the bvp4c solver. Outcomes are provided for three instances related to shape factor i.e. Platelet, Cylinder and Spherical. Using Multiple Linear Regression (MLR), we investigated how physical parameters of concern together with friction factor, are affected by a variety of parameters. It is remarked that the fluid’s velocity lessens as the variable viscosity parameter enhances. It is discovered that the temperature profile increases with the rise in exponential heat source parameter ([Formula: see text]). It is discovered that when [Formula: see text], the Nusselt number declines by 0.03588 (Platelet shape), 0.03562 (Cylinder shape), and 0.03489 (Spherical shape). It has been noted that magnetic field parameter (Mg) reduces the coefficient of skin friction. At [Formula: see text], the skin friction coefficient is seen to drop at a rate of 1.15018 (Platelet shape), 1.14871 (Cylinder shape), and 1.14476 (Spherical shape). There is an enhancement in the Sherwood number with the rise in Schmidt number (St) and chemical reaction parameter (Cr). At [Formula: see text] the Sherwood number is seen to rise at a rate of 0.248303 (Platelet shape), 0.248344 (Cylinder shape), and 0.248447 (Spherical shape). Furthermore, it is detected that the fluid’s temperature rises as the thermal radiation parameter enhances and the entropy generation increases as the variable viscosity parameter increases.

Variable fluid properties analysis for thermally laminated 3-dimensional magnetohydrodynamic non-Newtonian nanofluid over a stretching sheet

This article is mainly focused on the viscous flow of cu-water/Methanol suspended nanofluids towards a three-dimensional stretching sheet reformed by magnetohydrodynamic phenomenon. The viscous effect is considered as temperature dependent with water treated as a base fluid. Similarity conversions are employed to set forth the non-linear equations of this physical problem. An innovative model for 3D analysis for cu-water/Methanol nanofluid with an irregular viscosity is presented in the present study. Reynold’s model of viscosity is considered in the present study. Moreover, shooting technique is employed to elaborate the non-linear coupled governing equations with the relevant boundary conditions. The physical interpretation of these numerical calculations is presented through a graphical specimen of velocity, Nusselt number, temperature, and skin friction etc. The results of present model are showing quality harmony with the results of existing model. This model is being used for manipulating and designing the surfaces such as stretching/shrinking wrapping and panting devices in nanotechnology. The results also show the significant changes in flow characteristics with changing the value of stretching parameter. It is observed that with an increasing in nanoparticles volume fraction boundary layer thickness decreases. Further, it is also observed that with an increase in viscosity parameter, temperature increases because here we are considering temperature dependent viscosity.

MHD peristaltic transportation of radiative MWCNT-Ag/C2H6O2 hybrid nanofluid with variable characteristics

Present study addresses the flow and heat transportation for peristalsis of MWCNT-Ag/C2H6O2 hybrid nanofluid. Effects of temperature dependent thermal conductivity, viscosity, thermal radiation, inclined magnetic field, Joule heating and mixed convection are considered. Shape effects of nanomaterials are also addressed. A hybrid nanomaterial system is used with a 2% concentration of nanomaterials (50:50) in ethylene glycol. Thermal and velocity slip conditions are also employed. The mathematical model is simplified by using lubrication theory. The obtained dimensionless model is then numerically solved. Results reveal that temperature of hybrid nanofluid decreases with an increment in nanoparticles volume fraction. Heat transfer rate at the wall decays by increasing radiation parameter. The thermal efficiency of hybrid nanofluid (MWCNT-Ag/C2H6O2) is more pronounced as compared to ordinary nanofluid (MWCNT/C2H6O2) and base fluid (C2H6O2). Velocity increases with an increase in viscosity parameter. Pressure gradient declines with an augmentation in Hartman number and nanoparticles volume fraction.

Effect of viscoelasticity on the nonlinear dynamic behavior of dielectric elastomer minimum energy structures

Dielectric elastomer minimum energy structure (DEMES) formed by clinging a pre-stretched dielectric elastomer (DE) membrane to the compliant frame possess both material and geometrical nonlinearity. The viscous and hyperelastic nature of the DE membrane and coupling between the compliant frame and membrane forms the basis of these nonlinearities. Practically, DE membrane based DEMES actuator executes the transient motion which is significantly affected by the viscoelastic behavior of the DE membrane. Hence, for an efficient design of such devices, it is very important to analyse the effect of membrane viscoelasticity on the dynamic response of DEMES. In the present work, we have developed an analytical model to analyse the viscoelastic effect of DE membrane on the nonlinear dynamic behavior of the DEMES. In order to incorporate the viscous effect, the Zener rheological model consisting of a spring element connected in parallel to a Maxwell element is employed. The neo-Hookean material model based on the additive decomposition of the isotropic strain energy density into equilibrium and viscous parts is considered. The governing differential equation representing the dynamic behavior of DEMES actuator is derived using Euler–Lagrange equation of motion for non-conservative system. The isotropic viscous stretch is obtained by using the thermodynamically consistent evolution equation. The developed dynamic model predicts the initial shape, DC and AC response, periodicity of the DEMES for different values of viscosity parameter. The result reveals that the onset of equilibrium state delays as viscosity parameter increases. Further, the bending angle of DEMES actuator is significantly affected by the applied electric field and viscoelastic behavior of the DE membrane. Poincaré maps along with phase diagrams are presented to analyse the periodicity of nonlinear oscillation of the system. Further, the structure executes a stability transition (stable-unstable-stable) as the value of viscosity parameter increases. The obtained results can help in robust and efficient designing of DEMES based actuators subjected to dynamic loading.

Numerical study of the effect of viscoelastic properties of the material and bases on vibration fatigue of pipelines conveying pulsating fluid flow

The article presents the results of mathematical and computer modeling of the oscillatory processes of viscoelastic pipelines considering stationary external loads. A mathematical model of viscoelastic pipeline vibrations based on the theory of beams was developed when a pulsating fluid flows through it. Using the Bubnov-Galerkin method, based on a polynomial approximation of deflections, the problem was reduced to the study of a system of ordinary integro-differential equations, the solution of which was found numerically. A computational algorithm has been developed to solve vibration problems of composite pipelines conveying pulsating fluid. Stability and amplitude-time characteristics of vibrations of composite pipelines conveying pulsating fluid were studied at wide range of parameters variation of deformable systems and fluid flow. Critical fluid flow rates were found at which a viscoelastic pipe lost its rectilinear equilibrium shape. A singularity effect in hereditary kernels on vibrations of structures with viscoelastic properties was numerically studied. It was shown that with an increase in viscosity parameter of the pipeline material, the critical flow rate decreases. It was revealed that an increase in fluid pulsation frequency and excitation coefficient led to a decrease in the fluid flow critical rate. It was stated that an increase in Winkler bases parameters and the rigidity parameter of a continuous layer led to an increase in the critical flow rate.

Advective accretion flow properties around rotating black holes – application to GRO J1655-40

We examine the properties of the viscous dissipative accretion flow around rotating black holes in presence of mass loss. Considering thin disc approximation, we self-consistently calculate the inflow-outflow solutions and observe that the mass outflow rates decreases with the increase of viscosity parameter ($\alpha$). Further, we carry out the model calculation of Quasi-periodic Oscillation frequency ($\nu_{\rm QPO}$) that is frequently observed in black hole sources and observe that $\nu^{\rm max}_{\rm QPO}$ increases with the increase of black hole spin ($a_k$). Then, we employ our model in order to explain the High Frequency Quasi-periodic Oscillations (HFQPOs) observed in black hole source GRO J1655-40. While doing this, we attempt to constrain the range of $a_k$ based on observed HFQPOs ($\sim$ 300 Hz and $\sim$ 450 Hz) for the black hole source GRO J1655-40.

The Effect of Variable Viscosities on Micropolar Flow of Two Nanofluids

Abstract A study of nanofluids is carried out that reveals the effect of rotational inertia and other physical parameters on the heat transfer and fluid flow. Temperature-dependent dynamic viscosity makes the microrotation viscosity parameter and the micro inertia density variant as well. The governing nonlinear partial differential equations are converted into a set of nonlinear ordinary differential equations by introducing suitable similarity transformations. These reduced nonlinear differential equations are then solved numerically by Keller-box method. The obtained numerical and graphical result discloses many interesting behaviour of nanofluids. It is seen that the temperature gradient decreases with the increase in viscosity parameter. Also, it is observed that with the fixed values of micropolar parameter and viscosity parameter, the velocity gradient near the wall increases with increasing values of solid particle volume fraction parameter. A suitable comparison of results is also presented in this study.

Effects of variable viscosity and periodic boundary conditions on natural convection double-diffusive flow past a vertical plate in a slip flow regime

This paper studies the effects of variable viscosity and periodic boundary conditions on natural convection double-diffusive flow past a vertical plate in a slip flow regime when suction velocity oscillates in time about a constant mean. The fluid viscosity is assumed to vary with temperature. The problem is governed by a nonlinear and coupled linear system of partial differential equations. Perturbation method is employed to solve the equations. The influence of flow parameters on fluid temperature, concentration and velocity, skin friction, and rate of heat transfer have been presented graphically. It is observed that increase in viscosity parameter for the binary mixture of carbon dioxide ( Sc = 0.94) in air ( Pr = 0.71) increase velocity near the plate. In addition, the mean skin friction increases with increase in viscosity parameter.

Effects of Variable Viscosity and Thermal conductivity on Natural-Convection of Nanofluids Past a Vertical Plate in Porous Media

ABSTRACTThe effects of variable viscosity and thermal conductivity on the natural convection heat transfer over a vertical plate embedded in a porous medium saturated by a nanofluid are investigated. In the nanofluid model, a gradient of nanoparticles concentration because of Brownian motion and thermophoresis forces is taken into account. The nanofluid viscosity and the thermal conductivity are assumed as a function of local nanoparticles volume fraction. The appropriate similarity variables are used to convert the governing partial differential equations into a set of highly coupled nonlinear ordinary differential equations, and then, they numerically solved using the Runge-Kutta-Fehlberg method. The practical range of non- dimensional parameters is discussed. The results show that the range of Lewis number as well as Brownian motion and thermophoresis parameters which were used in previous studies should be reconsidered. The effect of non-dimensional parameters on the boundary layer is examined. The results show that the reduced Nusselt number would increase with increase of viscosity parameter and would decrease with increase of thermal conductivity parameter.

Radiatively and thermally driven self-consistent bipolar outflows from accretion discs around compact objects

We investigate the role of radiative driving of shock ejected bipolar outflows from advective accretion discs in a self consistent manner. Radiations from the inner disc affects the subsonic part of the jet while those from the pre-shock disc affects the supersonic part, and there by constitutes a multi stage acceleration process. We show that the radiation from the inner disc not only accelerate but also increase the mass outflow rate, while the radiation from the pre-shock disc only increases the kinetic energy of the flow. With proper proportions of these two radiations, very high terminal speed is possible. We also estimated the post-shock luminosity from the pre-shock radiations, and showed that with the increase of viscosity parameter the disc becomes more luminous, and the resulting jet simultaneously becomes faster. This mimics the production of steady mildly relativistic but stronger jets as micro-quasars moves from low hard to intermediate hard spectral states.

Flow and heat transfer affected by variable properties of nanofluids in natural-convection over a vertical cone in porous media

This paper attempts to theoretically analyze the effects of nanoparticles concentration gradient on the natural convection boundary layer flow of nanofluids around a vertical cone placed in a porous medium. The slip of nanoparticles is because of the Brownian motion and thermophoresis forces. The viscosity and the thermal conductivity of nanofluid are considered as a function of local volume fraction of nanoparticles. Two mathematical processes are performed. The first step is the simplification of the governing partial differential equations using appropriate similarity variables. The second step is the numerical solution of the obtained ordinary differential equations. Furthermore, based on the Buongiorno’s model, the new definition of the reduced Nusselt and Sherwood numbers is presented in details. The results reveal that the reduced Nusselt number would increase with increase of viscosity parameter and decrease with an increase of thermal conductivity parameter.

Properties of accretion shock waves in viscous flows around black holes

Accretion flows having low angular momentum and low viscosity can have standing shock waves. These shocks arise due to the presence of multiple sonic points in the flow. We study the region of the parameter space in which multiple sonic points occur in viscous flows in the absence of cooling. We also separate the parameter space in regions allowing steady shocks and oscillating shocks. We quantify the nature of two critical viscosities which separate the flow topologies. A post-shock region being hotter, it emits harder X-rays and oscillating shocks cause oscillating X-ray intensities giving rise to quasi-periodic oscillations. We show that with the increase in viscosity parameter, the shock always moves closer to the black hole. This implies an enhancement of the quasi-periodic oscillation frequency as viscosity is increased

Trapped Disk Oscillations and Stable QPOs in MicroQuasars

The observed quasi-periodic oscillations (QPOs) in low-mass X-raybinaries have been suggested to be probably related to the characteristicoscillation modes in the inner part ofa relativistic accretion disk. In this paper we study the trapped feature of these oscillation modes by considering the radial perturbations and viscosity effects. We find that the trappedoscillations are amplified significantly when the viscosity parameterincreases and the trapped size varies when the radial wavenumber and Mach number change. Our results support that the stablehundred-hertz QPOs and their low fractional rms amplitudes found intwo Galactic microquasars may be explained by some trapped non-damping oscillation modes in the inner part of accretiondisks around rotating black holes.