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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. [ABSTRACT FROM AUTHOR]

Motivated by emerging applications in bio-microfluidic devices, the present study rigorously examines the generalized Taylor–Gill hydrodynamic dispersion of a point source solute injected into a microchannel, influenced by a constant axial static electric field along the channel and charged surface with different wall potentials. The solute engages in a first-order irreversible chemical reaction at both the microchannel walls. By incorporating different wall potentials and absorptive coefficients at the lower and upper walls, the current transport model for electro-osmotic flows is extended to encompass a wider range of applications. The solute transport phenomenon is intricately modeled using the unsteady convective diffusion equation. Employing Gill's generalized dispersion model, a concentration decomposition technique, up to the third-order accuracy, we meticulously analyze the transport process. Furthermore, a comprehensive comparison between analytical outcomes and numerical simulations using the Brownian Dynamics method is undertaken, enhancing the robustness of the analytical approach. The scattering process is mainly analyzed with the help of exchange, convection, dispersion, and asymmetry coefficients, along with the mean concentration profile. The effect of initial solute release at various vertical locations in the microchannel is shown to exert a considerable impact on all the transport coefficients at initial times. [ABSTRACT FROM AUTHOR]

Bioconvection has shown significant promise for environmentally friendly, sustainable "green" fuel cell technologies. The improved design of such systems requires continuous refinements in biomathematical modeling in conjunction with laboratory and field testing. Motivated by exploring deeper the near-wall transport phenomena involved in bio-inspired fuel cells, in the present paper, we examine analytically and numerically the combined free-forced convective steady boundary layer flow from a solid vertical flat plate embedded in a Darcian porous medium containing gyrotactic microorganisms. Gyrotaxis is one of the many taxes exhibited in biological microscale transport, and other examples include magneto-taxis, photo-taxis, chemotaxis and geo-taxis (reflecting the response of microorganisms to magnetic field, light, chemical concentration or gravity, respectively). The bioconvection fuel cell also contains diffusing oxygen species which mimics the cathodic behavior in a proton exchange membrane (PEM) system. The vertical wall is maintained at iso-solutal (constant oxygen volume fraction and motile microorganism density) and iso-thermal conditions. Wall values of these quantities are sustained at higher values than the ambient temperature and concentration of oxygen and biological microorganism species. Similarity transformations are applied to render the governing partial differential equations for mass, momentum, energy, oxygen species and microorganism species density into a system of ordinary differential equations. The emerging eight order nonlinear coupled, ordinary differential boundary value problem features several important dimensionless control parameters, namely Lewis number (Le), buoyancy ratio parameter i.e. ratio of oxygen species buoyancy force to thermal buoyancy force (Nr), bioconvection Rayleigh number (Rb), bioconvection Lewis number (Lb), bioconvection Péclet number (Pe) and the mixed convection parameter (𝜀) spanning the entire range of free and forced convection. The transformed nonlinear system of equations with boundary conditions is solved numerically by a finite difference method with central differencing, tridiagonal matrix manipulation and an iterative procedure. Computations are validated with the symbolic Maple 14.0 software. The influence of buoyancy and bioconvection parameters on the dimensionless temperature, velocity, oxygen concentration and motile microorganism density distribution, Nusselt, Sherwood and gradient of motile microorganism density are studied. The work clearly shows the benefit of utilizing biological organisms in fuel cell design and presents a logical biomathematical modeling framework for simulating such systems. In particular, the deployment of gyrotactic microorganisms is shown to stimulate improved transport characteristics in heat and momentum at the fuel cell wall. [ABSTRACT FROM AUTHOR]

Abstract\nCULMINATIONSThe ureter typically experiences a frequency of one to five peristaltic contractions per minute. However, it is important to note that these contractions can be disrupted by various physical and mechanical irritants. Ionic contents in the urine make it electrically conducting and responsive to electromagnetic body forces. MHD can be deployed in bio magnetic therapy to control or mitigate symptoms associated with peristaltic pumping in the urinary system.  This article therefore focuses on the hydromagnetic effects on flow patterns of urine with debris (monoliths). The mechanism of urine flow is largely coordinated by the kidneys. The flow inside the ureter is interrupted by microliths, which are generated by the sedimentation of excretory products. To simulate this, a two-phase formulation is adopted, comprising the electromagnetic urological viscous fluid phase and the particulate phase for solid grains. The peristaltic propulsion of two-phase liquid in the ureter is simulated as a sinusoidal wave propagation of incompressible non-Newtonian fluid. The Williamson viscoelastic model is deployed for the rheology. Heat transfer is also included with Soret thermo-diffusion and viscous heating effects. Long wave and low Reynolds number approximations are employed based on lubrication theory. The mass, momentum, energy and concentration conservation equations with associated boundary conditions are rendered non-dimensional via appropriate scaling transformations. A numerical solution is achieved via BVP4C MATLAB quadrature.  Graphical visualizations of the velocity, temperature and concentration (solid grains) are given for the influence of suspension parameter (ζ), Hartmann number (M), Prandtl number (Pr), Weissenburg number (We), particle volume fraction (C), Eckert number (Ec), Soret number (Sr), Schmidt number (Sc). The novelty of the present work is therefore the simultaneous consideration of a generalized two-phase model, wall slip, non-Newtonian characteristics, cross diffusion, viscous dissipation, mass diffusion, magnetic body force and curvature effects in peristaltic urological transport, which has not been undertaken previously. The detailed simulations reveal that the flow velocity is reduced due to the presence of solid particles and the channel curvature, in comparison to the flow in an unobstructed channel devoid of solid particles. Enhancing the hydrodynamic slip parameter speeds up the movement of particles and fluid near the channel walls, boosts wall skin friction, raises pressure difference in the pumping area, and amplifies bolus magnitudes.The rise in peristaltic pumping results in a reduction in solid particle concentration, which is significant phenomena.This theoretical approach may aid in treating conditions such as Urinary Tract Infections (UTIs). The computations effectively demonstrate that significant manipulation of urological pumping characteristics can be achieved with an electromagnetic field. Some new features of two-phase ureteral dynamics are highlighted as relevant to magnetic therapy techniques, which may be beneficial to clinicians.A detailed new formulation is given for magnetohydrodynamic (MHD) two-phase Williamson non-Newtonian ureteral transport with mass diffusion, Soret cross diffusion, viscous heating and peristaltic wave propulsion.We compute numerically the pressure gradient, skin friction, Nusselt number, and wall shear stress in a planar channel with flexible walls, which serves as a model for the ureter under a transverse magnetic field.We also investigate the impact of Hartmann number and Weissenberg non-Newtonian number on fluid and particle phase velocities.The present work reveals some interesting insights into electromagnetic ureteral peristaltic multi-phase non-Newtonian thermo-solutal transport phenomena via extensive visualization.There is a strong suppression in the ureteral fluid phase velocity for greater magnetic field confirming the excellent flow control abilities of Magnetic Ureteral Therapy (MUT).A detailed new formulation is given for magnetohydrodynamic (MHD) two-phase Williamson non-Newtonian ureteral transport with mass diffusion, Soret cross diffusion, viscous heating and peristaltic wave propulsion.We compute numerically the pressure gradient, skin friction, Nusselt number, and wall shear stress in a planar channel with flexible walls, which serves as a model for the ureter under a transverse magnetic field.We also investigate the impact of Hartmann number and Weissenberg non-Newtonian number on fluid and particle phase velocities.The present work reveals some interesting insights into electromagnetic ureteral peristaltic multi-phase non-Newtonian thermo-solutal transport phenomena via extensive visualization.There is a strong suppression in the ureteral fluid phase velocity for greater magnetic field confirming the excellent flow control abilities of Magnetic Ureteral Therapy (MUT). [ABSTRACT FROM AUTHOR]

AbstractThis article presents both a theoretical and a numerical analysis of thermo-gravitational magnetic convection in electro-conductive Eringen micropolar fluids in a two-dimensional enclosure. The computational regime is bound with cold top, hot bottoms, and adiabatic side walls. The governing equations were transformed via scaled variables into dimensionless partial differential equations. A Finite volume method (FVM) is used to get a solution of the computational regime. Validation of the FVM solutions is included for non-magnetic special case from the literature. Streamline contours, isotherm contours, iso-microrotation contours (lines of constant angular velocity) and local Nusselt number at the left hot wall is depicted graphically for the impact of Hartmann (magnetic) number (Ha), Prandtl number (Pr), micropolar parameter (K) and Rayleigh number (Ra). A significant modification in internal circulation and micro-rotation in addition to temperature distribution is observed with increasing vortex viscosity parameter. Significant warping of isotherms is induced with stronger magnetic field and the mushroom-shaped core structure encountered at weak magnetic field transitions to a sigmoidal topology. [ABSTRACT FROM AUTHOR]

AbstractMagnetic nanoparticles are increasingly being deployed in smart coating systems due to their exceptional functionalities and abilities to be tuned for specific environmental conditions. Inspired by the emergence of tri-hybrid magnetic nanofluids which utilize three distinct nanoparticles in a single base fluid coating, the present article examines analytically and computationally the swirl coating of magnetic ternary hybrid nanofluid from a rotating disk, as a simulation of spin coating deposition processes in materials manufacturing. Owing to high temperature fabrication conditions, thermal radiative heat transfer is also considered and a Rossleand flux model deployed. CoFeO2-Ag-TiO2 hybrid nanoparticles are considered with Ethylene Glycol-Water (C2H6O2−H2O 40:60%) base fluid. A filtration medium is also featured (porous medium) adjacent to the disk and the Darcy-Forchheimer model is deployed to simulate both bulk matrix porous drag encountered at lower Reynolds numbers and inertial quadratic drag generated at higher Reynolds numbers. Thermal relaxation of the coating nanofluid is additionally addressed and a non-Fourier Cattaneo-Christov model is therefore implemented in the heat conservation equation. Viscous dissipation is also included in the model. The governing conservation equations for mass, momenta (radial, tangential and axial) and energy with prescribed boundary conditions are rendered into coupled nonlinear ordinary differential boundary layer equations via suitable scaling variables and the Von Karman transformations. The derived reduced boundary value problem is then solved with a Runge-Kutta numerical scheme and shooting scheme in MATLAB. Validation of solutions is included with previous studies. Radial and azimuthal velocities, temperature, radial skin-friction, azimuthal skin friction and local Nusselt number are computed for a range of selected parameters. A comparative assessment of mono nanofluid CoFeO2, Hybrid CoFeO2-Ag nanofluid and tri-Hybrid CoFeO2-Ag-TiO2 nanofluid is conducted. This combination of hybrid nanoparticles has never been examined previously in the literature and constitutes the significant novelty of the present work. Both radial and tangential velocity are depleted with increasing applied magnetic field whereas temperature and thermal boundary layer thickness are increased. [ABSTRACT FROM AUTHOR]

The diffusion of oxygen through capillary to surrounding tissues through multiple points along the length has been addressed in many clinical studies, largely motivated by disorders including hypoxia. However relatively few analytical or numerical studies have been communicated. In this paper, as a compliment to physiological investigations, a novel mathematical model is developed which incorporates the multiple point diffusion of oxygen from different locations in the capillary to tissues, in the form of a fractional dynamical system of equations using the concept of system of balance equations with memory. Stability analysis of the model has been conducted using the well known Routh-Hurwitz stability criterion. Comprehensive analytical solutions for the differntial equation problem in the new proposed model are obtained using Henkel transformations. Both spatial and temporal variation of concentration of oxygen is visualized graphically for different control parameters. Close correlation with simpler models is achieved. Diffusion is shown to arise from different points of the capillary in decreasing order along the length of the capillary i.e. for the different values of z. The concentration magnitudes at low capillary length far exceed those further along the capillary. Furthermore with progrssive distance along the capillary, the radial distance of diffusion decreases, such that oxygen diffuses only effectively in very close proximity to tissues. The simulations provide a useful benchmark for more generalized mass diffusion computations with commercial finite element and finite volume software including ANSYS FLUENT.

Measurement errors play an important role in the development of goniometric equipment, devices used to measure range of motion. Reasonable validity and reliability are critical for both the device and examiner before and after to testing in human subjects. The objective is to evaluate the concurrent validity and reliability of five different clinical goniometric devices for the purpose of establishing an acceptable measurement error margin for a novel device. We explored the validity and inter- and intrarater reliability scores of five goniometric devices namely (i) the universal goniometer (UG), a two-armed hand-held goniometer, (ii) the inclinometer (IC), featuring a single base, fluid level, and gravity-weighted inclinometer, (iii) the digital inclinometer (DI), functioning as both a DI and dynamometer, (iv) the smartphone application (SA), employing gyroscope-based technology within a smartphone platform application and (v) the modified inclinometer (MI), a gravity pendulum-based inclinometer equipped with a specialized fixing apparatus. Measurements were obtained at 12 standard angles and 8 human shoulder flexion angles ranging from 0° to 180°. Over two testing sessions, 120 standardized angle measurements and 160 shoulder angle measurements from 20 shoulders were repetitively taken by three examiners for each device. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated to assess reliability and validity. Concurrent validity was also evaluated through the execution of the 95% limit of agreement (95% LOA) and Bland-Altman plots, with comparisons made to the UG. The concurrent validity for all device pairs was excellent in both study phases (ICC > 0.99, 95% LOA - 4.11° to 4.04° for standard angles, and - 10.98° to 11.36° for human joint angles). Inter- and intrarater reliability scores for standard angles were excellent across all devices (ICC > 0.98, SEM 0.59°-1.75°, MDC 1°-4°), with DI showing superior reliability. For human joint angles, device reliability ranged from moderate to excellent (ICC 0.697-0.975, SEM 1.93°-4.64°, MDC 5°-11° for inter-rater reliability; ICC 0.660-0.996, SEM 0.77°-4.06°, MDC 2°-9° for intra-rater reliability), with SA demonstrating superior reliability. Wider angle measurement however resulted in reduced device reliability. In conclusion, our study demonstrates that it is essential to assess measurement errors independently for standard and human joint angles. The DI is the preferred reference for standard angle testing, while the SA is recommended for human joint angle testing. Separate evaluations across the complete 0°-180° range offer valuable insights., (© 2023. The Author(s).)