International Journal of Modern Physics B

Inquisitive researchers have studied the movement of peristaltic nanofluids due to the enlightening impact of nanoliquids in various technological and therapeutic fields, particularly in the fluids transport mechanisms known as peristalsis. The Casson fluid belongs to a group of non-Newtonian fluids that, according to a particular stress threshold, exhibit elastic solid behavior before changing to liquid behavior. These fluids are known as viscoelastic fluids and have several uses in engineering, food preparation, drilling and other fields. The Casson nanofluid model is used in this investigation. In order to better understand this, this study examines the peristaltic motion of a Casson nanofluid in a vertical layer with suction/injection. The resulting flow model is successfully simulated under the realistic assumptions of long wavelength and low Reynolds number after obtaining the governing conservation equations. By using workable transformations, the derived partial differential equations are mathematically converted into a dimensionless form. Analytical solutions have been found for the resulting flow problem’s temperature distribution, velocity, pressure rate per wavelength and concentration of nanoparticles. Using Wolfram Mathematica software, the impacts of all physical characteristics on temperature, velocity, concentration fields, pressure rate, frictional force and pressure gradient are graphically studied. The influences of thermophoresis parameter Nt raise the temperature and diminish fluid concentration. By raising the suction and injection parameter k values, the velocity in the directions of x and y is decreased. The pressure rate enhances by raising the Reynolds number and diminishes by enhancing the Grashof number.

The velocity of an unsteady flow of a viscous fluid of the second-grade MHD-type enclosed between two parallel side walls perpendicular to a plate was obtained by applying the integral transformation. The fluid is required to move by the plate, which over time $t=0^{+}$ subjected the fluid to shear stress. The solutions satisfy the given equation as well as the boundary and initial conditions, and they were separated into two types: steady state and transient state. Furthermore, through $h\to \infty$, we are able to recover the results found in the literature for motion across an infinite plate. Graphs depict the effect of the side walls and the time it takes to reach the steady state. The solutions are shown in graphs and discussed physically to examine the impact of different flow parameters. It is found that the fluid velocity decreases with an increasing fractional parameter $\beta$ and second-grade parameter $\alpha$. Also, it is noticed that the fluid velocity decreases with increasing values of Reynolds number and effective permeability. Numerous industrial products, including honey, paints, varnishes, coffee, chocolate and jelly, use this type of fluid flow concept.

The current work investigates the effects of oblique Lorentz force and Navier’s slip boundary condition on unsteady hybrid nanoliquid flow with three different base liquids (H₂O, CH₃OH and H₂O–EG) across a nonlinearly elongating surface set in a porous medium. This research considers the effects of viscous–Ohmic dissipation, nonlinearly variable thermal radiation, internal heat source, the Soret effect, first-order chemical reaction and thermal and solutal jump conditions at the boundary. Proper thermo-physical relationships for the hybrid nanoliquid have been established. Rosseland’s estimate for an optically thick regime is used when calculating the heat flow owing to radiation. The dimensional governing equations are translated into nondimensional forms using appropriate similarity transformations. The velocity, energy and concentration fields are numerically solved using a shooting strategy based on the secant iteration and the Runge–Kutta–Fehlberg method. The physical implications of several essential parameters on the hybrid nanoliquid velocity, temperature and concentration are investigated using graphical and tabular representations of numerical data. Furthermore, the multiple (quadratic) regression analysis reveals that physical parameters strongly influence the local skin friction coefficient, Sherwood and Nusselt numbers. For continuously growing values of the unsteadiness parameter, the velocity, thermal and concentration scattering declined everywhere within the boundary layer region.

In this research, we examine the mixed convection effects for peristaltic motion of tangent hyperbolic nanoliquid. On flexible channel walls, partial slip characteristics are applied. Influences of Ohmic heating and viscous dissipation are analyzed in the modeling. We evaluated the transportation of heat under nonlinear thermal radiation. The governing problem is first reduced into dimensionless form by using suitable transformations and then numerical technique is employed for the solution after utilizing small Reynolds number and large wavelength assumption. The problem is simulated employing the so-called Buongiorno’s formulation which includes the features of thermophoresis and random motion. In addition, a mass transport scheme is developed with first-order chemical reactions. The roles of sundry variables on velocity, coefficient of heat transfer, temperature and concentration are examined graphically. Velocity and temperature show similar behavior against thermal Grashof parameter. Concentration decreases for larger thermophoresis parameter. Heat transfer coefficient and temperature have decreasing effects against radiation parameter.

Topological invariants are crucial quantities for classifying materials with topological phases. Hence, their connections with experimentally measurable quantities are extremely important. In this context, circular dichroism (CD) provides a protocol to detect the Chern number ${{𝒞}}_0$ of the lowest energy Bloch band (LBB) of a semimetal. This hinges on the unequal depletion rates of the Bloch electrons from a filled LBB, under the action of a time-periodic circular drive, depending on the chirality of the polarization. According to the dimensionality of the system (i.e., whether it is two- or three-dimensional), the integrated differential rate for depletion has to be formulated a bit differently in order to relate it to ${{𝒞}}_0$. Our aim is to capture the nature of the CD response for semimetals with anisotropic band dispersions. We show that while the quantization of the CD response for the three-dimensional cases is strongly sensitive to anisotropy, the two-dimensional counterparts show a perfectly quantized response.

In this study, we constructed a numerical technique for the simulation of the convection–diffusion problem under convection dominancy. Lagrange interpolation technique is applied to obtain new expressions for the approximation of variable at the interfaces of control volume. Moreover, based on these interface approximations new numerical scheme is developed to approximate convection–diffusion phenomena. The Crank–Nicolson approach is applied for the temporal approximation. This newly constructed numerical scheme is unconditionally stable with second-order accuracy in time and space both. Numerical tests are carried out for the justification of the new algorithm. A comparison of numerical results produced by proposed technique and some other numerical approaches is presented. This comparison indicates that for convection dominant phenomena, the numerical solution of conventional finite volume method contains with non-physical oscillations which analyze that proposed numerical technique results in a high accurate and stable solution.

In this paper, we have analyzed the bifurcation of stagnation points in the non-Newtonian flow of the FENE-P fluid through a channel induced by peristalsis. The stream function for the flow under consideration is developed under negligible inertia and streamline curvature effects. A nonlinear autonomous system is developed for scrutiny of the critical points. A dynamical system approach is used to examine the stability of bifurcation points. Streamline patterns, and local and global bifurcation diagrams are plotted for analysis of the backward flow, trapping, and augmented flow regions. The impacts of important embedded parameters, i.e., extensibility parameter and Deborah number on local and global bifurcation diagrams, are also examined. The whole analysis reveals that two critical conditions appear in the flow field that are actually responsible for the conversion of backward flow to trapping and trapping to augmented flow. It is further seen that bifurcations occur at lower flow rates for increasing Deborah’s number while an opposite trend prevails for increasing the extensibility parameter. A comparison of bifurcations between planar and axisymmetric flows is also performed. It is observed that a greater area of the trapping region is encountered for axisymmetric flow than that for planar flow.

Two-dimensional graphene is widely used in the nuclear industry, computer simulation of the physical process of graphene irradiation damage can assist the study of microscopic dynamic processes that cannot be directly observed in irradiation experiments. The irradiation-induced microstructural change of 2D graphene sheets was studied using molecular dynamics simulations with a maximum primary knock-on atoms (PKA) energy of 180keV. The results show that using direct observation, the defects generated during the cascade collision process can be divided into three types according to the generation mechanism: defects by PKA damage (DPD), instantaneous defects by shock wave rippling (DSR), and permanent defects by shock wave overlapping (DSO). The atomic configuration of the final stage consists of various topological polygons; in general, octagons and polygons with fewer than eight sides are bulged, while polygons with more than eight sides are depressed. The largest topological polygon found by the simulation is a 13-sided polygon. In addition to atoms with a coordination number of 3 (originating from the perfect lattice structure of graphene), atoms with coordination numbers of 2 and 4 are produced. Atoms with a coordination number of 4 are generally enclosed by four polygons that have no more than six sides, while atoms with a coordination number of 2 are generally located between two polygons that have at least six sides.

The aim of this paper is to examine the combined effects of unsteadiness and thermal radiation on the flow of a mixture nanoliquid due to a shrinking disk. Investigation of flow near a stagnation-point naturally arises in several industrial sectors and is useful owing to its significance in thermal enhancement. The motion is persuaded by a radially stretched/shrinked exterior of the disk in adding to the flow near a stagnation point. As a result, this research examines the thermophysical belongings of the unsteady flow near a stagnation-point past a stretching/shrinking disk by using twin-kind nanoelements, viz. a mixture nanoliquid. Cu and Al₂O₃ nanoparticles have been considered in water to produce hybrid nanofluid. The numerous uses like electronic cooling system, heat exchangers and radiators are available. Using similarity transformations, self-similar equations have been obtained which are then solved numerically using MATHEMATICA software. Comparisons have been made with the available data in the literature and found a complete agreement for some special case of the problem. Double solutions subsist for equally stretched and shrinked disks, whereas a unique solution exists for the static disk. For flow past a stretching or a shrinking disk, a 27.79% of increase in warmth transport speed is noted for mixture nanofluid, contrasted to the nanoliquid. Hence, this study will be of interest to several scientists and engineers, owing its capability to augment the speed of heat transport in contrast to the regular nanofluids.

This paper enchases the performance of the inertial drag on the Buongirino model nanofluid flow past a curved stretching surface embedding within a permeable medium. The radiating heat transport property for the interaction linear approach of Rosseland thermal radiation vis-à-vis reacting species enriches the flow behavior. Further, this study is novel due to the consideration of convective boundary conditions for both the energy and solutal bounding surface condition in association with the slip velocity condition. In a practical situation, when the fluid and surface temperature are different, it is wise not to neglect the convective boundary conditions. The application of convective conditions is useful for the fabrication of the final product in the manufacturing processes. Further, the renovation of the proposed model is obtained for the suitable assumption of the similarity transformation. Traditional numerical technique, i.e., fourth-order shooting-based Runge–Kutta is the best choice for the solution of the set of the transformed equation for the assumed parameters within their specified range. Velocity contour for different parameters vis-à-vis the parametric behavior is presented graphically. Numerical validation as well as the statistical testing for the rate coefficients are the novel approaches of this study. However, interesting outcomes are deployed as follows: The enhanced Brownian and thermophoresis both encourage the fluid temperature, whereas thermophoresis decelerates the fluid concentration.

In this paper, the dust acoustic wave is studied in conditions where the dust temperature is not constant. This model includes negatively charged dust particles and thermal ions. The reductive perturbation technique is used and the new point in this study is the nonuniformity of the plasma temperature. The nonconstancy of the temperature is entered as a first-order perturbation in the calculations, and finally the modified Korteweg–de Vries (mKdV) equation is derived. The solution of the modified KdV equation clarifies the change in soliton shape of the wave when it moves in the perturbation plasma. We show how the soliton wave undergoes deformation and amplitude reduction during propagation when it encounters a region with a different temperature. The output of this research can be effective to better understand the wave behavior in a real plasma with nonuniform temperature.

This work investigates a non-Newtonian MHD Carreau nanofluid over a stretched vertical cylinder of an incompressible boundary layer with mobile microorganisms. The flow exists in permeable media and follows the modified Darcy’s law. An unchanged normal magnetic strength to the walls saturates the system. Ohmic dissipation, heat source, modified chemical reaction with activation energy properties, heat, volumetric nanoparticles fraction as well as microorganism profiles are covered. Thermal conductivity and mass diffusivity are taken as functions of heat and nanoparticle concentration, correspondingly. The fundamental governing system of nonlinear partial differential equations (PDEs) is converted into nonlinear ordinary differential equations (ODEs) by employing appropriate similarity transforms. The latter system is numerically analyzed through fourth-order Runge–Kutta (RK-4) simultaneously with the shooting process. The numerical outcomes showed that the curvature coefficient, magnetism and chemically activated energy perform a significant role in the velocity, heat, nanoparticle and chemical organism distributions. The impacts of several physical restrictions are tested and portrayed in a group of graphs. It is observed that the presence of microbes and nanoparticles, which are described in buoyancy terms, causes the flow to decay and slow down. By lowering the buoyancy and bio-convection characteristics, this infection can be prevented. With the development of all heat-related elements, heat transfer is enhanced, which is a significant feature associated with the current flow. These insights are important and useful in various physical and engineering fields.

A numerical analysis has been presented for stream of a mixture nanoliquid over a slendering stretched sheet in company of an external magnetic meadow under boundary layer approximations. This investigation is performed to look at the impacts of variable thickness on balanced two-dimensional (2D) flow of a hybrid nanofluid under border-level approximations as it has wider technological applications in various industries. A variable magnetic field has been considered here. An effort has been taken in this piece to report the joint impacts of variable thickness and MHD on hybrid nanoliquid flow over a slendering stretched sheet as no one has reported such effects. Here lies the novelty of the work. By applying appropriate similarity transformations, the leading partial differential equations (PDEs) are converted to ordinary differential equations (ODEs) and the solutions of the nonlinear equations are subsequently obtained numerically using shooting technique. To hold up the soundness of the statistical outcomes, an assessment is completed with the accessible known outcomes for a few meticulous cases of this study. The consequences of a variety of parameters on motion of fluid and heat transport are analyzed and talked about exhaustively with the help of tabular and graphical representations. It is found that Lorentz force slows down the border-level flow and thickens the momentum border level width. Skin-friction coefficient reduces with the decreasing values of m for $m>0$ which is obvious as superior values of m help the liquid to move faster over the exterior and the thickness of the boundary layer augments with the mounting values of m ($m>0$). Thus, it can be concluded that the fluid motion is controlled by the power-law index m ($m<1$) since the motion slows down for $m<1$ and goes faster for $m>1$.

This paper reports density functional theory (DFT) on LiMgP half Heusler alloy doped by the transition metal elements (Ti, V, Fe and Ni) determined by present results, in which the half-metallicity besides ferromagnetism behavior is estimated. The electron spin polarization of Ti(3$d)$ is around the $E_F$ and the Ti${}^{2+}$ will have two electrons, of which two electrons occupied the $e^{+}$. Then, this orbital is set on the Fermi level. When the conduction band of the orbitals $e^{-}$, $t_2^{+}$ and $t_2^{-}$ is empty, LiMg${}_{0.95}$Ti${}_{0.05}$P displays the half-metallic characteristic, where the ferromagnetic (FM) conduct fits the double-exchange coupling. For LiMg${}_{0.95}$V${}_{0.05}$P alloy, the charge state is closer to V${}^{2+}$ electron configuration, which predicts the following configuration, in which two electrons are occupied by $e^{+}$ and one electron is occupied by $t_2^{+}$ at the upside of $E_F$. Based on LiMg${}_{0.95}$Fe${}_{0.05}$P alloy, the presence of the half metallicity at the downside of $E_F$ due to (3$d)$orbital is clear. A hybridization between the Fe(3$d)$ and the P(3$p)$ orbitals is in the range −0.35 — −0.04 Ry. For LiMg${}_{0.95}$Ni${}_{0.05}$P alloy, the predicted charge is Ni${}^{2+}$ and exhibits the half-metallic on the downside of the $E_F$ which is occupied by $t_2^{-}$ minority state. For LiMg${}_{0.95}$TM${}_{0.05}$P alloy, (TM = Ti, V, Fe and Ni), the half-metallic conduct is estimated with 100% spin polarized on the Fermi level. The spin moment of TM is $\parallel M^{\mathrm{\text{Ni}}}\parallel <\parallel M^{\mathrm{\text{Ti}}}\parallel <\parallel M^{\mathrm{\text{V}}}\parallel <\parallel M^{\mathrm{\text{Fe}}}\parallel$, where their total magnetic moments $\parallel M^{\mathrm{\text{Tot}}}\parallel$ are in correlation for those Ni, Ti, V and Fe, where the trend also is $\parallel M_{{\mathrm{\text{LiMg+}}}_{0.95}{\mathrm{\text{Ni}}}_{0.05}\mathrm{\text{P}}}^{\mathrm{\text{Tot}}}\parallel <\parallel {\mathrm{\text{M}}}_{{\mathrm{\text{LiMg}}}_{0.95}{\mathrm{\text{Ti}}}_{0.05}\mathrm{\text{P}}}^{\mathrm{\text{Tot}}}\parallel <\parallel M_{{\mathrm{\text{LiMg}}}_{0.95}{\mathrm{\text{V}}}_{0.05}\mathrm{\text{P}}}^{\mathrm{\text{Tot}}}\parallel <\parallel M_{{\mathrm{\text{LiMg}}}_{\mathrm{\text{0.95}}}{\mathrm{\text{Fe}}}_{0.05}\mathrm{\text{P}}}^{\mathrm{\text{Tot}}}\parallel$. Likewise, based on LiMg${}_{0.95}$TM${}_{0.05}$P alloys, the crystal field splitting ($e,t_2)$ observation stated that the doped elements conduct a trend having the following range ${\mathrm{\Delta }}_{(e,t_2)}^{\mathrm{\text{Ni}}}<{\mathrm{\Delta }}_{(e,t_2)}^{\mathrm{\text{Ti}}}<{\mathrm{\Delta }}_{(e,t_2)}^{\mathrm{\text{V}}}<{\mathrm{\Delta }}_{(e,t_2)}^{\mathrm{\text{Fe}}}$. From these observations, it is predicted to have a correlation between magnetic moments of (Ti, V, Fe and Ni) and the crystal field splitting.

Coal-fired thermal power plants are currently converting their technology to supercritical and ultra-supercritical in order to meet the world’s energy demands. An important component in this technology is the superheater of the boiler, which operates at higher temperatures and above the critical pressures. For the design and reliable operation of a superheater tube bundle, thermal and structural analyses are crucial. This study focuses on the superheater tubes bundle of a 660MW coal-fired supercritical boiler. The superheater model is simulated to investigate the thermal characteristics such as temperature distribution, total heat flux and directional heat flux and structural parameters such as von Mises stresses, equivalent strains and total deformations. Different materials such as martensitic steel, austenitic steel and nickel–titanium are compared based on thermal and structural analysis. It is claimed that thermal performances of martensitic steel are more impressive as compared to superheater materials. The lower strain appeared for austenitic steel as compared to martensitic steel.