International Journal of Modern Physics B

Considerations on the current status of the theory of superconductivity, the bibliometric H-index, and H. C. Andersen’s tale about the emperor’s new clothes. First appeared in the APS Forum on Physics and Society quarterly newsletter, January 2020.

To meet the energy requirement of the world, this work addresses the MHD flow of ternary hybrid nanofluid between two rotating and stretchable disks having porous medium. Thermal radiation effects along with velocity slips at the interface of fluid and disk are considered in this study. Three types of nanoparticles, namely, Al₂O₃ (alumina), CuO (copper oxide) and Cu (copper), have been taken with water as the host fluid. The flow and thermal characteristics of hybrid (Al₂O${}_3+\mathrm{\text{CuO}}$) and ternary (Al₂O${}_3+\mathrm{\text{CuO}}+\mathrm{\text{Cu}}$) nanofluids formed by the combination of nanoparticles have been observed. This combination aids in the breakdown of dangerous compounds, environmental purification and the cooling of other equipment. The corresponding equations are modeled in terms of PDEs, and these PDEs are transformed into ODEs using Von Karman similarity transformations. The resulting equations are solved by using finite difference method based ND solver. The rate of heat transfer increases with the rise in thermal Biot numbers. Moreover, the solution predicts that for variations in radiation parameter from 0.5 to 1.5, heat transfer upsurges 88% for traditional nanoparticles, 92.4% for hybrid nanoparticles while for trihybrid nanoparticles, it grows up from 0% to 95%.

In this paper, we scrutinize the impacts of multi-slip with multi-stratification on nanoparticles MHD Carreau fluid flow through a time-dependent stretching sheet with thermal radiation. We obtain the solution upon the application of the Keller-box scheme with an implicit finite-difference scheme. The influence of thermal stratification and concentration stratification is also being measured. The differentce parameters’ influence on the fluid flow is illustrated in diagrams and the quantitative numerical findings are well-argued. For increasing heavier species, fluid index and the reaction rate parameter with Prandtl number $\mathrm{\text{Pr}}=5.0$, 10.0 and 15.0 will decrease the concentration of fluid within its boundary limits. Behavior of Weisenberg number on fluid velocity is studied. Moreover, fluid velocity declines as the unsteady parameter rises, while the temperature and concentration significantly decrease. Higher values of solutal and thermal stratification parameters result in decay of velocity and thermal boundary layer thickness while the fluid temperature reflects the opposite behavior.

A three-part tape-enhanced tube was used in the current hypothetical solar unit to save the most radiation possible. The three parts were joined at different angles ($\beta$). The parameters of the carrier base fluid after mixing with CuO nanopowder were calculated using a homogeneous model. By adjusting the range of Y${}^{+}$, multiple layers were used to precisely depict the behavior of flow close to the wall. The results show the components of irreversibility as bar charts, velocity contours, and exergy drop contours. The tape angle ($\beta$) and inlet velocity were thought to be the main driving forces. An evaluation of the accommodation’s validity using numerical data shows that it is sufficient. The wall temperature decreases by about 0.0257% as the nanofluid angle rises and more collisions with the wall take place. Xd falls off roughly 5.19% from 0^∘ to 45^∘ and 5.87% from 0^∘ to 90^∘ as the angle $\beta$ rises. As $\beta$ rises, the entropy of friction increases by 9.88%. The outer wall cools by about 0.87% and Xd falls by about 92.3% when $\beta =45^{\circ }$ and Re rises.

This paper examines the thermal transfer attributes of ZnO-H₂O Walter’s-B nanoliquid flow alongside an upright cone in the bearing of slip mechanism, radiative heat flux, and non-uniform heat source. We adopted suitable similarities to convert the nonlinear PDEs into ODEs and solved the transformed governing system by employing the bvp5c solver package in Matlab software. The prime novelty of this research is to compute the effective thermal diffusivity of the nanoliquid via the Maxwell and Xue nanomodels. Further, simultaneous results are deliberated for Maxwell and Xue cases via pictorial outcomes under various controlling limitations, such as velocity slip, radiative heat flux, buoyancy, viscoelastic, and volume fraction of nanomaterial. The thermal transmission rate of nanoliquid reported by the Xue nanomodel is higher than the Maxwell nanomodel. Therefore, the Xue nanomodel effectively works to enhance the thermal conductivity of the liquids with viscoelastic nature. Further, this study is helpful in industrial processing, where control over heat transport is required.

With a numerical method, the discharging process within a container with a double complex cold surface has been scrutinized in this paper. The inherent process makes conduction as the main mechanism and the temperature equation includes three terms and two of them are time-dependent which was discretized by means of implicit technique. Adding nanoparticles within water can enhance the rate of heat release and concentration of powders and their shapes can affect the properties of nanomaterial. Single phases for estimating the features of nanomaterial were applied. The maximum period of process takes 326.95s which is 1.36 times lower than the case of pure water. Increasing the shape factor can enhance the speed of process and its impact is less than concentration of additives.

A hydro-dynamic thermal fully developed forced convective heat transfer analysis of magneto-hydrodynamics fluid flow through an annular sector duct is presented in this paper. Two types of thermal boundary conditions i.e., axially uniform heat flux along with peripherally uniform temperature (known as H1-condition) and, axially and peripherally uniform temperature (known as T condition), have been considered to carry out the thermal analysis of fluid. The velocity components along r and $\theta$ direction are transformed into algebraic form by using power law discretized scheme, whereas cross-sectional pressure $P(r,\theta )$ is estimated with the help of well know technique $SIMPLER$. The governing partial differential equations are solved by numerically with the help of $MATLAB$ code. Furthermore, simulated results have been compared with the existing results of literature to validate the results. From the results, it is noted that hydro-dynamically and thermally impacts relate directly by increasing the Hartman number, (M). It is further reported that the effect of magnetic field becomes insignificant for the higher number of fins, N. The findings of the present analysis will be applicable in various types of thermal systems.

In this paper, the problem of finding the velocity profile of fully developed laminar flows through ducts of arbitrary cross-sections is investigated. The method which is used is based on a perturbative approach, although some nonperturbative exact results are also obtained. The main quantity which is addressed is the specific conductivity. This is a dimensionless quantity, which is independent of the size of the duct and the properties of the fluid, depending on only the shape of the duct. Some examples are studied is detail, for which the numerical values of the specific conductivity are determined, in the form of perturbative or exact results.

The present investigation computes the heat transport phenomenon of the magnetohydrodynamic (MHD) flow of CuO-Ag/H₂O hybrid nanofluid over a spinning disc. The authors are confident that there is very less analysis covering the fluid flow containing silver and copper oxide nanoparticles over a rotating disk. Therefore, the authors are interested to consider the water-based nanoliquid flow over a spinning disk. Furthermore, the velocity slip and thermal convective conditions are taken into consideration. The formulation of the problem is made in the form of PDEs and is then converted into the nonlinear ODEs by employing suitable similarity transformations. The homotopic analysis approach is applied for the semi-analytical solution of these resulting equations. The convergence of homotopic approach has also revealed with the help of figure. The performance of the hybrid nanofluid flow velocities and temperature has been shown in a graphical form against distinct flow parameters. Also, the numerical results of skin friction coefficient and Nusselt number have been calculated in a tabular form. The outcomes of the current problem show that the increase in the skin friction of the water-based copper oxide nanofluid is greater than the water-based silver nanofluid at 4% of the nanoparticle volume fraction. Also, the skin friction of the hybrid nanofluid is increased by 8% compared to the silver nanofluid at 4% of the nanoparticle volume fraction. Furthermore, the heat transfer rate of the water-based copper oxide nanofluid is greater than the water-based silver nanofluid at 4% of the nanoparticle volume fraction. Also, the heat transfer rate of the hybrid nanofluid is 52% greater than that of silver nanofluid at 4% of the nanoparticle volume fraction. It is found that the Nusselt number of the hybrid nanofluid is highly affected by the embedded parameters as compared to nanofluids.

Fe_xCu${}_{100-x}$ binary alloys attracted much attention owing to their rich magnetic phase diagram and the challenges of achieving single phases in these systems. Despite early efforts put toward studying the physical properties of low-Cu doping in Fe–Cu alloys, a detailed understanding of the magnetic, structural and electrical properties of high Cu doping in Fe–Cu alloys remains not clear. In this report, we use X-ray diffraction (XRD), scanning electron microscopy, electrical transport and magnetic measurements to gain more insight into Fe${}_{15}$Cu${}_{85}$ single-phase alloy system. Experimental findings show that the samples exhibit a second-order phase transition, which is consistent with the classical mean-field model. Moreover, negative magnetoresistance is observed at all temperatures and explained through classical models.

Reiner–Rivlin nanofluid flow due to rotating disk has significance in manufacturing of computer disks, pumping of liquid metals, spin coating, centrifugal machinery, turbo-machinery, crystal growth and rotational viscometer. In light of such real and relevant industrial applications, this study deals with the numerical investigation of unsteady rotationally symmetric flow of Reiner–Rivlin nanofluid over a stretchable rotating disk. The purpose of this investigation is to explore heat transfer characteristics of Reiner–Rivlin nanofluid subject to radial stretched surface implementable in several thermal systems. For facilitation of heat transport in complex thermal systems, mathematical models, such as Cattaneo–Christov, Buongiorno and nonlinear thermal radiation models, are assumed to be introduced. Runge–Kutta–Fehlberg technique along with shooting method is used for numerical computation of the transformed equations. It is captivating that radial and circumferential velocities decelerate with rise in Reiner–Rivlin and stretching strength parameters, respectively. Amplified thermal relaxation and Reiner–Rivlin parameters led to diminution of wall temperature gradient. Nanoparticle concentration profiles exhibit opposite behavior in response to escalation of activation energy and reaction rate parameters.

Eshelby tensors in elasticity are obtained for two-dimensional (2D) decagonal quasicrystal containing an ellipsoidal inclusion. Based on the intrinsic strain formula and Mori–Tanaka theory, the effective elastic properties of 2D decagonal composites are obtained. The effects of inclusion volume fraction and inclusion aspect ratio on elastic properties of composites with 2D decagonal quasicrystal are discussed.

In this paper, we obtain a variety of analytical wave solutions of a ($2+1$)-dimensional extended shallow water wave equation. The applications of the governing equation are enormous in ocean modeling and investigation of moist-convection properties in atmospheric dynamics. Two powerful mathematical approaches, the $exp(-\mathrm{{\rm Y}}(g))$-expansion method (EEM) and the generalized projective Riccati equations method (GPREM), were used to find closed-form traveling wave solutions. In addition, the breather wave solutions were described using the Cole-Hopf transform, derived with the help of Hirota bilinear method (HBM). Eventually, we obtain 46 closed-form solutions in explicit form. The general form of obtained solutions include trigonometric, rational, exponential and hyperbolic function solutions. To illustrate the physical significance of some novel results, we provided contour, two- and three-dimensional graphics under the suitable free choices of unknown parameters. The dynamical shapes of these solutions are one soliton, multiple solitons, kink, anti-kink, lump and periodic solutions. We believe that the applied methods of this work are well-organized, genuine and powerful mathematical tools for solving the nonlinear evolution equations (NLEEs) occurring in the study of ocean science and engineering.

In this paper, a non-isothermal study of the calendering processes is presented using Carreau–Yasuda model along with nonlinear slip condition introduced at the upper roll surface. The flow equations for the problem are developed and converted into dimensionless form with the help of dimensionless variables and then finally simplified by a well-known lubrication approximation theory. The final equations are solved numerically using “bvp4c” to find stream function and velocity profiles, while the hybrid numerical method which is the combination of shooting and finite difference methods is used to solve the energy equation. Graphs show the impact of the concerned material parameters on various quantities of interest. The pressure distribution decreases with the increasing values of the slip parameter and Weissenberg number. The mechanical variables show an increasing trend with the increasing values of the slip parameter and Weissenberg number. The temperature distribution increases with an increase in the Brinkman number, while temperature shows declining trend near the roll surface with the increasing values of the slip parameter. The force separating the two rollers, total power input into both rolls, increase with the increasing values of the Weissenberg number and slip parameters. The results show that the Newtonian model predicts higher pressure in the nip zone than the Carreau–Yasuda model. It is interesting to note that for the case of shear thinning, the Carreau–Yasuda model predicts 30% less pressure in the nip region when compared to the Newtonian model.

Transmittance self-oscillation discovered in amorphous GeSe₂ films has attracted considerable interest, while its underlying mechanism remains controversial. We suggest that the oscillation is governed by at least two kinds of changes; one occurs in absorption for thin ($\sim 6\mu$m) films and the other in refractive-index for thick ($\sim 1$mm) plates. We also detail a model, which assumes recoverable micro-crystallization. An idea for increasing the oscillation frequency is proposed for possible applications.