The propagation of nonlinear ion-acoustic solitary waves (IASWs) is investigated in a magnetized anisotropic electron ion plasma with Cairns distributed electrons. The ions are warm and exhibit pressure anisotropy due to the external magnetic field. The energy integral equation for the wave potential is derived via Sagdeev approach. The effect of various physical plasma parameters (nonthermality, ion pressure anisotropy) on the characteristics of IASWs is investigated in detail. The present investigation could be of interest to space and astrophysical plasma systems having ion pressure anisotropy, for instance, in the magnetosphere and near earth magnetosheath.

The non-homogeneous aspect and dynamical feature of a radiating mixture of an upper-convected Maxwell nanofluid and gyrotactic motile microorganisms are revealed numerically in this investigation during its two-dimensional mixed convective motion nearby a convectively heated vertical surface and a uniform magnetic field source. Based on relevant physical and mathematical backgrounds, the conservation laws (i.e. equations of continuity, momentum, heat balance, solid nanoparticles’ concentration, and gyrotactic motile microorganisms’ concentration) monitoring the present flow problem are derived appropriately in the form of partial differential equations. By making use of specific transformations and rearrangements, these differential equations are converted thereafter into a gigantic structure of first-order ordinary differential equations. By executing computationally an appropriate bvp4c subroutine, the resulting boundary layer equations are handled accordingly for well-defined physical constraints. Afterward, the computing unitless characteristics (i.e. velocity, temperature, solid nanoparticles’ concentration, gyrotactic motile microorganisms’ concentration, skin friction coefficient, Nusselt's number, Sherwood's number, and motile microorganisms’ transfer rate) are discussed exhaustively via graphical and tabular illustrations. As prominent outcomes, it is demonstrated that Joule's heating effect and Lorentz's forces exhibit an enhancing influence on the heat and mass transport phenomena within the nanofluidic medium with a dissimilar dynamical impact.

The current study is carried out to analyze the unsteady MHD flow of fractional-order Oldroyd-B nanofluid and heat transfer via a semi-spectral computational method. The governing model for MHD naturally convective fractional-order Oldroyd-B is expressed in terms of a coupled PDE system. To analyze the numerical solution novel scheme is suggested, where finite difference is used to approximate the temporal derivative whereas spatial variable is approximated via operational matrices which are computed using Chelyshkov polynomials. The proposed scheme transforms the nonlinear system of PDEs into a system of linear algebraic equations. Relevant theorems are presented to support the mathematical justification of the operational matrices-based method whereas stability analysis is being made for the proposed computational algorithm. The impact of involved physical parameters on velocity temperature, skin friction, and Nusselt number profiles are studied numerically. The impact of the magnetic field drops the velocity behavior whilst the effect of buoyancy forces on velocity is the opposite. The radiation pass through the nanofluid transmits the energy to the fluid particles and eventually causes an increase in the temperature of the fluid whereas similar behavior is noticed in heat generation. The substantial effect of the fractional parameter is noted for smaller values.

A theoretic model formalism is developed to investigate the nonlinear gravito-electrostatically coupled streaming instability modes excitable in viscoelastic quantum dusty plasmas. It consists of weakly correlated light electrons, ions; and strongly correlated heavy dust grains. We treat the inertialess electrons as a degenerate quantum fluid, inertial ions as a classical inviscid fluid, and massive dust particles as a classical viscoelastic fluid. It considers a dimensionality-dependent parameter, γ = [(D − 2)/3D], termed as the Bohmian quantum correction prefactor (D: System dimensionality). A weakly nonlinear perturbative analysis against the defined hydrodynamic homogeneous equilibrium procedurally results in a unique conjugational construct of gravito-electrostatically coupled extended pair Korteweg-de Vries (ep-KdV) equations with atypical multiparametric coefficients. A numerical analysis upshots in two distinct classes of nonlinear wave structures: (a) Electrostatic regular periodic pulse-like patterns, and (b) Self-gravitational extended bell-shaped solitons. The amplitude variations of the streaming-induced fluctuations are analyzed especially with the constitutive electron-ion equilibrium streams and with the Galilean reference frame velocity in an elaborate comparative platform alongside geometric trajectory analysis illustratively. The main implications and applications of this semi-analytic study are finally outlined from an extensive perspective.

The dynamics of the steady flow, heat transfer, and MHD in Casson fluid (CF) were currently studied in the literature. But studies on unsteady flow are rare. In those studies, the boundary conditions at the boundary layer, for the directed and perpendicular velocities, and the temperature field, were only taken constants. Or they were taken to depend linearly on the directed distance. The study of CF over a free-stretching surface is too complicated and was not considered in the literature. Our objective, here, is to study the dynamics of CF with boundary conditions at the free surface, where similar solutions of the the steady flow, unsteady flow and temperature are found. This is completely a novel problem. The exact solutions for the steady flow, unsteady flow and temperature field dynamic equations are found via the extended unified method. The only existing tool, to deal with this problem, is the use of Lie symmetry which requires a hierarchy of long steps. The solutions obtained are evaluated numerically and represented in graphs. It is found that the steady-state flow exhibits two, upper and lower, layers with variant behavior which agree with what is found in the literature. It is, also, observed that in the unsteady state case that the directed and perpendicular velocities tend to zero asymptotically when the lateral space variable and the time tend to infinity. While it is observed that the temperature attains a constant value. An approach is presented to study the stability of the steady-state flow and temperature. It is found that the steady-state temperature is unstable for varying the magnetic field strength, viscosity and mass density. While, when varying the Casson parameter Λ, it is stable when and it is unstable for . This is in contrast to the case of steady-state flow which is shown to be stable.

The investigation of double-negative acoustic metamaterials for, among other things, achieving acoustic damping and the suppression of the localization of waves in acoustic systems constitutes an interesting field of study. Vibrational waves in one-dimensional random systems containing double-negative acoustic metamaterials are investigated in this study. Participation number is used to analyze the localization of waves in acoustic metamaterial multilayers with thickness disorder. PN is observed to become very large inside the DN band near the characteristic frequency where the effective mass approaches zero. For acoustic metamaterial multilayers following the Fibonacci sequence, the frequency dependence of their transmittance was numerically investigated.

In this paper, a multiscale non-reciprocity device based on the layered topology of one-dimensional (1-D) photonic crystals is studied, which can meet the functions of XOR logic gate, magnetic field sensing and refractive index sensing. Modulating by the external magnetic fields, sharp transmission peak (TP) is obtained in the terahertz (THz) range (the value of TP is more than 0.9), by changing the two different magnetic fields applied to the particular medium layers, TP enables XOR logic phenomena at the same frequency point. Simulation shows that with the detection of physical quantities changes, the frequency point of TP will vary. Therefore, through the location of TP, the sensing functions of magnetic field and refractive index can be realized, moreover the optimum performances of quality factor (QF), sensitivity (S), the figure of merit (FOM), and the detection limit (DL) belonging to them are 1323.45, 0.01 (2πc/d 0)/T, 35.93 T−1, 1.39 × 10−3 T and 1381.88, −0.0061 (2πc/d 0)/RIU, 13.57 RIU−1, 3.7 × 10−3 RIU. Additionally, the device also realizes the non-reciprocity of electromagnetic waves (EWs) via the introduction of magneto-optical media InSb and the change of EWs incident angle, which means that XOR logic gate, magnetic field, and refractive index sensing detection respectively have positive and negative scales.

In the presented paper, by using deep neural network (DNN), the vibrational response associated with a three-layered circular sector plate, in which the core is made of honeycomb structures and the face sheets are made of composites reinforced with graphene oxide powders is studied. Two-directional generalized differential quadrature method (2D-GDQM), as the solution method, is employed to discretize and solve ordinary differential equations. By using a momentum-based optimizer in a neural network system, the optimum value associated with different parameters is acquired. First-order shear deformation theory (FSDT) is utilized in order to attain the displacement fields based on which the governing equations are extracted. The frequency of the system is attained by using the adaptive learning method. Additionally, the results as well as the formulation of the current study are validated by using other papers. It was shown that the DNN-based model in studying these three-layered systems has less error than other models. Lastly, the impact of various parameters for the honeycomb core as well as reinforced composite face sheets, was investigated in detail.

The trapping and acceleration of an externally injected electron bunch into a donut-like wakefield driven by an intense Laguerre-Gaussian (LG) laser pulse in the plasma are studied. The results because of the doughnut shape profile of the LG laser pulse and low divergence propagating can be used in applications such as accelerating a hollow electron bunch. For the high-energy acceleration in the donut wake, while keeping the emittance conserved and making the Relative Energy Spread (RES) a few percent, the suitable initial bunch parameters are investigated. Careful optimization of the test electron bunch parameters allows one to obtain a minimum suitable RES and a stable emittance of the accelerated bunch in the donut wakefield.

This paper examined the MHD flow over the Riga surface in the presence of a permeable medium with Soret and Dufour effects. The Cattaneo-Christov model is adopted to scrutinize thermal and mass diffusion. The thermal conductivity of the fluid is assumed to be varying with respect to temperature. Melting condition is also imposed. The governing system is reduced to the ordinary differential system after applying the transformation. For the analytical solution, the optimal homotopy method is used. The graphical outcomes for velocity, temperature, concentration, and entropy are plotted for different estimations of various physical variables. The velocity profile enhances for larger estimation of the fourth-grade fluid parameter but decreases for higher values of magnetic and inverse Darcy numbers. The higher values of Suret number temperature and concentration profiles show opposite results. The entropy rate enhances for radiation and Brinkman number.