International Journal of Modern Physics B

The heat and mass transfer in normal impingement of the Hiemenz stagnation-point flow of a viscous nanofluid on a bidirectional stretching sheet under the influence of the magnetic field is investigated. In a recent study, Weidman (Meccanica, vol. 53, p.833, 2018) has analyzed the phenomenon of the Hiemenz stagnation-point flow over the biaxially stretching sheet. Dual solutions have been found in this study for the various values of $\alpha$ (streamwise stretching rate) and $\beta$ (cross-stream stretching rate). In the present work, the mechanism of thermal and solutal energy transport in the Hiemenz stagnation-point flow of nanoliquid is studied in the view of thermophoretic and Brownian forces. The solutions of similar ordinary differential equations (ODEs) for flow and energy transport in viscous nanofluid are computed with help of bvp4c numerical technique. The impact of dimensionless parameters on flow field and energy transport is presented graphically and discussed with physical reasoning. The outcomes reveal that the higher magnitude of Lorentz force declines the flow field in cross-stream and vertical directions, but conflicting behavior is noted for streamwise velocity component in the case of $\alpha <1$ and $\alpha >1$. Both thermophoresis and Brownian motion of nanoparticles enhance the energy transport in Hiemenz flow of viscous fluid. The results of the present study are validated through the shear stress parameters with a previously published study.

Human survival is purely based on the environment. Through natural calamities or man-made depredation, the pleasant existence is disturbed. Trees provide not just foliage for the environment but also a pleasant atmosphere for the human population. One of the most serious threats to the forest and ecology is the pine wilt disease (PWD). It is a devastating disease that kills pine trees in a matter of weeks. The pine-wood nematode Bursaphelenchus Xylophilus causes PWD. This study emphasises on the infectious model of PWD engaging the $q$-homotopy analysis transform method ($q$-HATM) to a leading fractional operator Caputo–Fabrizio fractional time derivative to arrive for superior understanding. The denouements are presented in the forms of plots and tables. At last the paper supports to examine the real-world models and helps to forecast their behavior that communicate the instructions considered in the models.

The main purpose of this study is to scrutinize the axisymmetric flow of second-grade nanofluid with variable viscosity near a stagnation point under the influence of the Cattaneo–Christov double diffusion model. A Riga plate is assumed to be the source of the three-dimensional flow. The consequences of the anisotropic slip conditions and the Buongiorno model are included in the formulation of the constituting equations of the fluid flow. The highly nonlinear ordinary differential equations are developed with the executions of the relevant similarity transformations on the problem’s governing equations. For the asymptotic analysis, the appropriate expansions are implemented on the nonlinear system of ordinary differential equations. The bvp4c technique of the MATLAB package is implemented on the nonlinear ordinary equations for the numerical solutions. In order to explore the impact of the parameter slip factor on the pattern of velocities, temperature, and concentration profiles, several graphs are plotted. From this study, we conclude that the normalized velocities boost up with the amplification in the slip factor parameter but the temperature profile exhibits a declining behavior. The concentration field exhibits the accelerating behavior relative to the slip parameter.

In this paper, a ring-slotted spiral local resonant phononic crystal structure is investigated. The energy band characteristics and transmission losses of the structure are calculated using the finite element method. The numerical results show that the structure can generate bandgap in the range of 23.54–102.87 Hz. Combined with the modal coupling theory, the vibrational modes of the ring-slotted spiral local resonant phononic crystal are analyzed to reveal the bandgap formation mechanism of the structure. The effects of the various dimensional parameters and material hardness on the bandgap of the structure are analyzed by varying them. The results show that by varying the filling radius of silicone rubber in the ring-slotted spiral local resonant phononic crystal, the structure can be made to have an onset frequency of 19.42 Hz and generate a bandgap in the range of 19.42–78.16 Hz. A new idea is provided for the application of phononic crystal in low-frequency environment for vibration and noise reduction.

In this paper, the spectral response of uniform and apodized (Gaussian, hyperbolic tangent, apod1, sine, and raised sine) FBGs is analyzed for sensing applications. The reflectivity at Bragg wavelength as well as for sidelobes was assessed as a function of grating length and apodization profiles. The FBG strain and temperature sensors were simulated and a linear response between applied strain or temperature and the wavelength shift is observed. The results indicate that the sensitivity of the sensor is found to be affected both by the grating length and apodization type. The typical strain and thermal sensitivity values are 1.223 pm/$\mu 𝜀$ and 13.60 pm/${}^{\circ }$C, respectively. The results suggest that Gaussian, sine, and raised sine profiles have lower sidelobe strength and reliable sensitivities. The key finding from this study specifies that the ideal grating length must be preferably between 5 and 10 mm for a good sensing behavior.

This paper deals with a unified presentation traveling wave solutions for the Mukherjee–Kundu equation which is a variant of the well-known nonlinear Schrödinger equation. A Weierstrass function approach has been employed to derive a Weierstrass elliptic function solutions, which can be reduced to the Jacobian elliptic function solutions through the conversion transformations. Due to the reductions of the Jacobian elliptic function solutions, the solitary wave solution and the trigometric period wave solution can be found by $m\to 1$ and $m\to 0$, respectively. In addition, the features of the obtained traveling wave solutions are represented graphically with the appropriate parameters.

For practical purposes, the study of ternary hybrid nanofluid flows near stretching/ shrinking surfaces, including heat generation/ absorption and velocity slip, has enormous value. It is crucial to understand how fluid mechanics deals with stagnation point flow, which is a common phenomenon in both engineering and scientific domains. In the evaporation process, the polymer enterprises, and the aircraft counter jet, the stagnation point flow may be found. An unsteady stagnation point flow is used to explore a ternary hybrid nanofluid (Cu–TiO₂–Al₂O₃/ polymer) in relation to a convectively heated stretching/ shrinking sheet. This research also considers the velocity slip condition in addition to the traditional surface under no-slip conditions. The differential equations and their partial derivatives are changed to ordinary differential equations by applying approved similarity transformations. The MATHEMATICA operating system employs the Shooting with Runge–Kutta-IV process to explain the reduced mathematical model. When preliminary assumptions are appropriate, the technique may provide solutions. According to the data, nanoparticle volume fraction has an effect on the skin friction coefficient and local Nusselt number. The coefficient of skin friction decreases when velocity slip occurs at the border, while the rate of heat transfer increases. According to the research, increasing the unstable parameter led to large increases in the coefficient of skin friction and heat transfer as opposed to just altering velocity slip. The outcomes show that ternary fluid has a greater skin fraction and heat transmission profile than hybrid and traditional nanofluids for all parameters. The recent evidence and published results for a particular case were contrasted to validate the findings, and good agreement was established.

Some of the fundamental properties of the nanofluids affect not only the transport phenomenon but also enhance the the heat transfer characteristics. The advancement in Rotatory machine technology can also be attributed mainly to a lot of research work that had been done on rotating disk flows with addition of nanoparticles in the base fluid. Taking cue of these developments, we examined the nanofluid (Cu+H₂O) flow over a rotating disk moving upward/ downward with viscous dissipation by reducing the governing Navier–Stokes equations into ordinary differential equations using appropriate transformations and then numerically evaluated them by the BVP Mid-rich scheme in Maple software. The study of velocity and thermal profiles is carried out and examined graphically. The results show that the upward movement of the disk escalates the radial and azimuthal velocity profiles along with the thermal gradient. In contrast, the addition of nanoparticles decreases the heat transfer rate at a constant disk movement.

In this paper, the adsorption behavior of Na atom on T-carbon (111) surface is investigated in detail by first principles calculations. The adsorption of Na atom on the T-carbon (111) surface is a chemical adsorption with excellent stability. The minor opening of the bandgap is present. The charges transfer from Na atom to C atom, which leads to a transition of the bonding properties from covalence to ionicity. For the H-site adsorption system, the adsorption energy is the lowest, indicating that the system is the most stable. At the same time, C-Na has the lowest bond population, indicating its strong ionic property. Additionally, the dielectric loss of the adsorbed system reduces, especially for the H-site adsorption, which is conducive to the improvement of the service life in electron material devices. In absorption spectrum, the peak values decrease and shift to the lower energy direction, resulting in the appearance of redshift phenomenon. The reflection peak and energy loss values are greatly reduced, in which the trend is most obvious for the H-site adsorption. The above analysis results provide a theoretical basis for the application of photosensitive devices and open a window on the design and control the micro-nano devices.

A heat exchanger is a device that transmits heat energy from one object to another, or within the same object. Examples of heat exchanger include a boiler, an oven and a cooker. Experimental techniques for testing these devices make it more costly and time-consuming. Consequently, computational fluid dynamics (CFD) can manage heat exchanger systems and their performance with ease. The actual impacts of what is being examined may then be predicted computationally which yields a precise output with approximate results. The designed geometry includes a rectangular duct with an inlet, outlet and two obstacles of equal height. The Navier–Stokes equations for the fluid flow are used. During the meshing process, the continuous geometric space of an item is divided into thousands or more forms, which helps to correctly identify the object’s physical shape. The desired model is computed numerically. Finite volume method (FVM) is used to study the results at a low Reynolds number (around $2.3\times {10}^6)$. The goal is to theoretically analyze the transmission of heat and fluid resistance to the flow. The CFD findings with experimental data are compared to confirm the model predictions. A CFD model based on the FVM and experimental data from a flow cell is used to study how fluid moves through ducts. This study focuses on the pressure, velocity and temperature fields of a fluid moving through a rectangular duct. As the top wall fluid temperature rises, the temperature distribution changes. Increasing fluid flow declines the temperature distribution. Temperature distribution grows with duct heat flow. As the flow rate rises, so does dispersion. Furthermore, as flow rate and velocity distribution drop, pressure distribution rises.