International Journal of Modern Physics B

The stenosis builds up and its progression in the artery causes serious damages, which may lead to death. This research aims to investigate the non-Newtonian properties of the pulsatile blood flow through the multi-stenotic inclined artery. The effect of external body acceleration is considered, and blood is taken as Rabinowitsch fluid in this work. The mathematical model representing the proposed problem is transformed into a dimensionless form by applying the assumption for mild stenosis. The dimensionless mathematical equations are solved using the perturbation method. The solutions of mathematical equations are investigated graphically to analyze the impacts of various physical constraints. We find that strong non-Newtonian effects lead to an increase in flow velocity and wall shear stress. The stenosis’s presence and progression in the artery reduces the flow velocity. The stenotic artery (diseased artery) is found to have less flow rate than the healthy artery. It is noted that the vertically held conduit effectively has a larger flow velocity and wall shear stress than the horizontal one. External body acceleration is noted to have an impact that raises velocity and wall shear stress.

An efficient spin–photon interface plays a significant role in building quantum network and distributed quantum computing with solid-state spin system, e.g., nitrogen-vacancy (NV) center in diamond. Solid-state spin system has the advantages of excellent portability and long coherence time, however, it suffers from a critical drawback of low efficiency of spontaneously emitted photons in the zero phonon line. This poses a severe challenge for the generation of an efficient interface between solid-state spin and photon. Here, we propose a method to establish a coherent interface between photon and solid-state spin system which is coupled to a trapped ion via a quantum transducer. Our method provides a new route to establish an efficient spin–photon interface allowing the generation of entanglement between distant spins.

Single crystals of Thiourea Cadmium hydrogen borate (TCHB), a hybrid nonlinear optical (NLO) material, are grown from an aqueous solution by slow evaporation solution growth technique at ambient temperature. Characterization studies have been conducted to probe the nonlinear effects of the crystal. The crystalline nature of TCHB is explored using the single crystal X-ray diffraction technique. The chemical composition is resolved by the Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray analysis. UV–Vis spectral studies analyze the transparency of the crystal. Optical studies illustrate the UV cut-off wavelength to be 285nm with wide window of transparency in the infrared and visible regions. The optical and electrical conductivity studies indicate superior optical response essential for optical computing and photonic applications. The Kurtz powder test has confirmed the NLO capability. The thermal stability is analyzed through a thermogravimetric study. Dielectric and AC conductivity measurements carried out over a wide range of frequencies (100Hz to 5MHz) for various temperatures establish the semiconducting and photonic capacity of TCBH crystal to be used as photodiodes, optical fibres and laser lights.

In this research, we have employed the Density Functional Theory (DFT) to successfully study the structural, elastic, thermoelectric, and optoelectronic properties of hexagonal halide perovskites CsGeX₃ ($\mathrm{\text{X}}=\mathrm{\text{I}}$, Cl, and Br). We used the Modified Becke–Johnson (MBJ-GGA) potential approximation to profoundly describe the band structure. The compounds of this interesting study are ductile, anisotropic, and mechanically stable. Our study showed that the optical properties are significant, among which are the following: the absorption is higher in the ultraviolet range, and the transmittance reaches a maximum level, which is 80% in the visible and infrared ranges. These substances can be employed in various optoelectronic systems that work in visible and ultraviolet energies. Furthermore, the transport properties are remarkably improved and reached the ZT $\sim 1$. These characteristics proved that they have an interesting potential for thermoelectric uses. We emphasized that this study provided the theoretical foundation of these structures’ elastic, electronic, and optical properties.

The transport phenomena of Casson nanofluid flow between two parallel disks subject to convective boundary conditions are analyzed in this paper. The mathematical model incorporates the impact of thermophoresis and Brownian motion since the Buongiorno’s nanoliquid model is adopted to characterize the nanoliquid’s transport features. The appropriate similarity transformations are applied to obtain the resulting nondimensional ordinary differential equations from the basic governing equations. The resulting ordinary differential equations and the associated boundary conditions are solved analytically by adopting the homotopy perturbation technique. Further, a statistical experiment is conducted to identify notable flow parameters which cause significant impact on the heat transfer rate. The characteristics of critical pertinent parameters on the flow field are graphically manifested. It is worth noting that the Casson nanofluid velocity escalates by augmenting the magnetic field parameter in the case of injection near the disks. Nanoparticle concentration is considerably diminished with an increment in thermophoresis parameter. In the cases of equal and unequal Biot numbers, the heat transfer rate is promoted with higher values of the Brownian motion parameter. Among the Casson fluid parameter, squeezing parameter and magnetic field parameter, the heat transfer rate discloses the highest positive sensitivity with the lowest value of the Casson fluid parameter.

Originality: A novel category of working fluids, consisting of two substantial components diffused in a conventional fluid, has been identified and investigated widely in recent years. These types of fluids are called hybrid nanofluids.

Problem statement: A wide range of engineering and industrial structures, including heat-transferring components, energy production, extrusion procedures, engine cooling purposes, thermal structures, thermal exchangers, chemical procedures, manufacturing processes and hybrid power plants, have been proposed for use with nanomaterials with improved thermal properties. These nanomaterial-based applications hold the promise of improved performance and efficiency in a variety of technological and industrial processes. The heat transmission and magnetohydrodynamic stagnation significance flow of hybrid nanofluids Fe₃O₄–ZrO₂ and Fe₃O₄/water, the form factor of a stretched cylinder under the influence of heat production, nonlinear thermal radiation and nanoparticle volume fractions have been investigated in this study.

Methodology: Utilizing proper similarity transformations, the processes of partial differential equations are further transformed into nondimensional solutions of ordinary differential equations. The bvp4c approach is employed to achieve a numerical solution. The flow and temperature profiles are displayed as a function of the contained factors. Graphs show the effects of changing the physical characteristics involved. Tables emphasize the skin friction factor and Nusselt numbers.

Results: The temperature profile of fluids diminished due to an increment in the values of the temperature relaxation parameter and Eckert number. When the porosity factor is increased the temperature of fluids is improved. The effects of streamlines for various components are discussed. The 3D surface, contour plots and residual plots for various factors have also been investigated.

Applications: Hybrid nanofluids have the potential to improve heat transfer efficiency in a variety of technical applications, including cooling structures, heat exchangers and thermal energy storage systems.

This analysis theoretically investigates the transport phenomena of mixed convection flows in an enclosure of rectangular geometry saturated with a permeable medium filled with an electrically conducting nanofluid. An inclined magnetic field is taken into consideration. Buongiorno’s model is utilized to characterize the nanoliquid. The enclosure has adiabatic walls and hot slits. A uniform cold temperature is maintained at the enclosure’s lower and upper walls. The enclosure’s vertical walls are thermally insulated with hot slits at the center of the walls. This kind of analysis on mixed convective, electrically conducting nanofluid flows in enclosures finds applications in smart nanomaterial processing systems and hybrid electromagnetic nanoliquid fuel cells. The Marker-And-Cell (MAC) method is utilized to solve the transformed nondimension system of governing equations subject to the fitted boundary conditions. The effects of key physical parameters on streamlines, isotherms, iso-concentration contour plots and the heat transmission rate are examined. The simulations demonstrate that the Richardson number has a predominant impact on the thermo-solutal features of nanofluid flow in the rectangular enclosure. Variations in magnetic field and buoyancy ratio parameters exert a notable influence on the iso-concentrations and isotherms. An increase in the Darcy number values exhibits a tendency to magnify the local heat transfer rate. Higher Grashof number values reduce the local Nusselt number profiles. The effect of porous parameter is significant in the streamlines, isotherms and iso-concentrations. Thus, the porous medium can significantly control the transport phenomena in the enclosure. The concentration, temperature and velocity contours are strongly modified by the variations in the Grashof number.

In this paper, a polarization-insensitive magnetic tunable perfect metamaterial absorber is analyzed which shows its functionality as a refractive index (RI) sensor. The unit cell structure of reported absorber consists of a cross-shaped Indium Arsenide (InAs) array over aluminum ground plane and has dimensions less than ${\lambda }_c/4$ with thickness of 7.5$\mu \mathrm{\text{m}}$ and periodicity of 9$\mu \mathrm{\text{m}}$ making it an ultra-thin absorber. The proposed absorber provides an average absorption of 99.99% on the implementation of magnetic field (B) at 0.4T. The resonance frequency and corresponding absorption rates can be controlled by varying the magnetic field from $B=0.1$–0.4T which provides high absorption as well as shift in the frequency spectrum by 0.3THz/T. Additionally, parametric analysis has also been done to confirm the selection of the optimum value of the designed parameters of the structure. Furthermore, simulation results reveal that the proposed structure is very sensitive to the change of RI values in the surroundings thus, the proposed structure can be employed as a RI sensor high sensitivity of 1.083THz/RIU over the range of 1–1.6RI. In addition, the result shows that the sensor can detect different chemical compounds such as ethanol, gasoline, paraffin, sodium chloride, carbon disulfide with an average sensitivity of 0.925THz/RIU. Thus, the proposed absorber with obtained sensitivity can be utilized as a biochemical sensor, making it one of the best contenders for chemical industry uses in diagnosis of different hazardous chemicals as well as finding its applicability in biomedical uses.

This paper discusses the high heat transfer demand from application prospects. Hybrid nanofluid is a well-known liquid with higher heat transfer capabilities. Here, the time-dependent flow of hybrid nanocomposite, by hybridizing the metal (Cu) and metallic oxide (Al₂O₃) and inserting them into water-based nanofluid, is examined. The flow takes place over the upper half of a parabolic surface. The modified Buongiorno model is used to express the physical phenomenon in mathematical equations form. The governing system of partial differential equations (PDEs) is reduced to a system of ordinary differential equations (ODEs) by applying certain transformations. Computation of the final equations has been done by a numerical scheme, known as the Keller-box method. The significance of dimensionless flow causing physical parameters is shown through graphs and tables. The findings reveal that among the hybrid nanofluids with two types of nanoparticles varying from 0% to 5%, a nanofluid having 5% of both nanoparticles is the one with the maximum surface drag force and heat transport rate, which are 41.8% and 22.7% higher to water, respectively. A higher amount of Al₂O₃ than Cu results in a suitable hybrid combination for application purposes to produce higher cooling rate with less surface drag. Also, the thickness of the surface, unsteadiness, nanoparticles suspension and power index of wall temperature enhance the heat transfer rate. Thin parabolic surfaces experience less drag and have larger boundary layer thicknesses (momentum, thermal and concentration) as compared to thicker parabolic surfaces. Also, the addition of copper slows down the hybrid fluid flow field, but alumina magnifies the mobility of hybrid fluid.

In this paper, a phononic crystal with acoustic black hole (ABH) characteristics is designed based on the compression effect of ABHs on acoustic wavelengths. The simulation results show that the lower limit of the first bandgap of the phononic crystal with ABH is reduced by 127.8Hz, the upper limit is increased by 694.4Hz, and the bandgap width is increased by 822.2Hz compared with that of the phononic crystal without ABH. The mechanism of bandgap expansion is discussed based on the mechanism of bandgap formation and the acoustic modulation effect of the ABH. The influence of the geometric and material parameters of the ABH on the bandgap is analyzed. The ABHs offer a new way of optimizing phononic crystals, and this work can be used as a reference for their design.

This paper introduces a broadband electromagnetic wave absorber with characteristics of polarization-independence and wide-angle stability based on resistive films with a three-dimensional (3D) configuration. The absorber consists of a 3D dielectric substrate array covered by a resistive film, which not only broadens the operation frequency band but also improves the absorption with large incidence angles. Simulated results indicate that the absorber achieves wideband absorption with over 90% absorptivity in the frequency range of 5.7–41.8GHz, corresponding to a relative absorption bandwidth of 152%. Due to the high symmetry of the structure, the absorber is insensitive to polarization angles. Moreover, the presented design maintains wave absorption greater than 90% when incidence angle reaches 70^∘ due to its 3D structure that ensures high absorption for wide incidence angles. The mechanism of this structure is investigated through surface current and power consumption distribution, while optimization parameters are analyzed for achieving the desired bandwidth. This absorber has the advantages of wide-band absorption and excellent stability under oblique incidence angles, making it potentially useful in applications such as electromagnetic shielding and energy harvesting.

Based on the hexagonal honeycomb structure and the tri-ligament chiral honeycomb structure, this paper proposes a hybrid material structure with low-frequency elastic wave suppression below 100Hz. Based on the finite element method and Bloch’s theorem, the energy band structure was calculated, and the formation of the band gap and the wave-propagation properties of the structure were carefully studied, the wave attenuation performance of the composite structure was simulated, and the influence of material properties and geometric parameters on the width and position of the band-gap distribution was discussed. The results show that the structure can generate a good band gap in the low-frequency range of 100Hz, and the wave propagation is suppressed obviously. Demonstrating its potential in practical applications, the research in this paper provides a theoretical basis for the manufacture of low-frequency vibration damping equipment and instruments, and provides a scheme for the design of metamaterials with low-frequency band gaps.

Over the past six decades, dye laser technology has improved substantially. The usage of solid matrices containing laser dyes is becoming more and more popular as a viable substitute for the traditional liquid dye solutions. In this research, we designed and built a tunable solid dye laser device which consists of three main parts. (i) The active material producing the laser beam, which is a polymer rod [glycidyl methacrylate (GMA) polymer] doped with the laser dyes pyrromethene 597 (PM-597) or Nile blue (Nb-690). (ii) The pumping source is xenon linear flashlamp driven by a homemade power supply. (iii) Two broadband mirrors providing the optical feedback stable optical resonator. The properties of the gain medium and hence the laser emission characteristics were determined, and the results showed the efficiency of the homemade tunable solid dye laser device, that is suitable for a variety of applications.

This paper examines the effect of rotation on thermal instability under Hele-Shaw cell saturated by Casson nanofluid using both linear and nonlinear ways. The nanofluid model incorporates Brownian and thermophoresis diffusion. While conducting an analysis of nonlinear stability numerically using the truncated Fourier series method, analysis of linear stability is performed analytically using the normal mode methodology. The outcomes are all displayed graphically. The results demonstrate that the rotation has dual effect on Hele-Shaw parameter as well as Casson parameter, for higher value of rotation it has destabilizing effect and it stabilizing  the system for lower values of rotation. Lewis number and concentration Rayleigh number promote the onset of convective motion within the system. On the other hand, rotation stabilize the system. Understanding the behavior of heat and mass transportation, the concentration of nanoparticles and fluid phase, utilize the Nusselt number when Nusselt numbers are assessed as a function of time, it is found that the variation of the rotation, Hele-Shaw and Casson parameter has a major influence on the heat and mass transfer. Both steady and unsteady weakly nonlinear analyses are performed to understand the heat transport in the system. It is concluded that the Casson nanofluid parameter has both stabilizing and destabilizing impact depending upon the rate of rotation and therefore this work can be possibly utilized in both places, where heat removal and heat conservation are required.

This attempt demonstrates the nature of mass and heat transportation in non-Newtonian Reiner–Philippoff liquid flow over moving surface by considering zero and nonzero normal mass flux conditions and transverse magnetic field. Thermophoresis and Brownian movement is accounted due to the Buongiorno model of nanofluid. The expressions of flow are reframed through appropriate variables into pairs of self-similar expressions. Further, these self-similar expressions are executed numerically through the Shooting procedure (Runge–Kutta 4th order). Numerical benchmarks and graphical illustrations are prepared to visualize the role of influential constraints on interesting quantities. It is observed that Lorentz force is beneficial in obtaining effective velocity and heat transfer. Improvement in thermophoresis factor enriches temperature field in case of active control while reverse nature is observed in passive control situation.