Parallel Plate Research Articles

Exploring the potential of heat transfer and entropy generation of generalized dusty tetra hybrid nanofluid in a microchannel

Caputo–Fabrizio time-fractional derivatives are the subject of this paper. This article generalizes the concept of dusty Tetra hybrid nanofluid moving freely via convection between infinite vertical parallel static plates. Free convection and buoyant force cause the flow and transmit the heat. In addition, there is a consistent distribution of spherical dust particles over the whole flow. It is the temperature difference between the two regions that sets off free convection. Free convection takes heat transfer into account. The dust Tetra hybrid nanofluid classical model employs non-dimensional variables to achieve a dimensionless form. We also convert the dimensionally-free model into a fractional generalized dusty Tetra hybrid nanofluid model. In this paper, we use the finite sine approach to analytically solve the governing equations of the generalized Dusty Tetra hybrid nanofluid model. In this article, we generalize the concept of a dust-filled Tetra hybrid nanofluid freely flowing between infinite vertical parallel plates. We found an analytical solution to the governing equations for the generalized dusty Tetra hybrid nanofluid by combining the Finite Sine Fourier and Laplace transforms. Understanding the mechanics of velocity and temperature profiles requires the use of numerical computation for a variety of embedded factors. In-depth statistical analysis and charting of data are features of this investigation. Using Mathcad-15, we plot the profiles of the Tetra hybrid nanofluid, dust particles, and temperatures to see the findings physically. Also determined are the skin friction and Nusselt number. The rate of heat transfer decreases with time, as seen in Table 1. Similarly, as seen in Table 2, raising the fractional parameter results in a higher skin friction. In addition, the energy profile of both velocities increases with increasing tetra hybrid nano fluid volume percent, albeit the fraction's contribution decreases with time. Since the fractional models are more accurate, they also provide more potential outcomes. When all the facts are considered, these choices may out to be the best.

Drift current-induced tunable near-field energy transfer between twist magnetic Weyl semimetals and graphene

Abstract Both the nonreciprocal surface modes in Weyl semimetal (WSM) with a large anomalous Hall effect and the nonreciprocal photon occupation number on a graphene surface induced by the drift current provide a promising way to manipulate the nonreciprocal near-field energy transfer. Interestingly, the interactions between nonreciprocities are highly important for research in (thermal) photonics but remain challenging. In this study, we theoretically investigated the near-field radiative heat flux transfer between a graphene heterostructure supported by a magnetic WSM and a twist-Weyl semimetal (T-WSM). The nonreciprocal surface mode could be changed by the separation space between two Weyl nodes and the twist angle. Notably, we found that in the absence of a temperature difference between two parallel plates, nonequilibrium fluctuations caused by drift currents led to the transfer of near-field radiative heat flux. Furthermore, these nonreciprocal surface modes interacted with the nonreciprocal photon occupation number in graphene to achieve flexible manipulation of the near-field heat flux size and direction. Additionally, graphene adjustable flux in the case of a temperature difference between the two plates was also discussed. Our scheme can provide a reference for near-field heat flux regulation in nonequilibrium systems.

Multi-objective optimization of electrokinetic energy conversion efficiency and entropy generation for streaming potential driven electromagnetohydrodynamic flow of couple stress Casson fluid in microchannels with slip-dependent zeta potentials

The present study develops a new mathematical approach to the pressure-mediated streaming potential flow of couple-stress Casson fluids with the influence of slip-dependent zeta potential between two parallel plates in a microchannel. The lateral electric and transverse magnetic fields are externally applied to control the fluid flow. A multi-objective optimization technique was implemented by utilizing the non-dominated sorting genetic algorithm (NSGA-II) by varying different constraints to maximize the electrokinetic energy conversion efficiency and minimize the irreversibility of the system. The present results show that the couple stress and Casson parameters influence the development of streaming potential, electrokinetic energy conversion (EKEC) efficiency, temperature, Nusselt number, and Bejan number for asymmetric velocity slip and temperature jump circumstances. The viscous dissipation, Joule heating, and thermal radiation parameters significantly affect the heat transfer. According to the present results, the EKEC efficiency increases with a slip-dependent zeta potential of couple stress Casson fluid, couple stress fluid, Casson fluid, and Newtonian fluid by 45.92 %, 47.10 %, 42.81 %, and 37.68 %, respectively, compared to that for the slip-independent zeta potential. At the centre of the microchannel for the jump boundary conditions, temperature increases by 2.95 % compared to no jump boundary conditions.

Fully developed opposing mixed convection of a Jeffery tri‐hybrid nanofluid between two parallel inclined plates subjected to wall‐slip condition

AbstractWe analyze the effect of wall slip on the fully developed reverse mixed convection of Jeffery nanofluids between two inclined parallel plates with uniform wall heat flux conditions. The theory of tri‐hybrid water‐based nanoparticles with unique shapes, namely, cylindrical (copper), spherical (titanium oxide), and platelet (aluminum oxide) for heat transfer enhancement is utilized since it has better heat performance applicable in a dynamic of fuels and coolant in automobiles as compared with regular Newtonian fluid and nanofluid. The equations describing the above transport phenomena are nondimensional through appropriate scale transformations. Analytical solutions for velocity, temperature, and pressure distributions are obtained. Four different flow regimes including no reversal, bottom reversal, top reversal, and on both walls reversal are found for different combinations of buoyancy and pressure. Particularly, we notice that the wall slip significantly affects flow reversal. Furthermore, we notice that Magyari 's conclusion that the results of the homogeneous nanofluid flow model can be recovered from the corresponding Newtonian fluid model has great limitations. Besides, the effect of several physical factors on velocity and temperature distributions and important physical quantities, including skin friction coefficient and Nusselt number, are analyzed and graphically discussed.

Physics of generalized couette flow of immiscible fluids in anisotropic porous medium

This study presents an investigation on the generalized Couette flow of two immiscible Newtonian fluids in an anisotropic porous medium. The flow occurs between two parallel plates, driven by the combined effects of an axial pressure gradient and the movement of the upper plate. The region between the plates is filled with an anisotropic porous medium characterized by directional permeability. An exact solution is derived for the proposed problem by considering appropriate boundary and interface conditions. The slip condition is employed at the lower plate of the channel which has a significant role in the flow mechanics of fluids flowing through porous medium. The effects of directional permeability on the flow of immiscible fluids are explored, and specific cases are presented. This study reveals a significant influence of directional permeability on the flow velocity of both fluids. Furthermore, quantitative conclusions are drawn regarding the shear stress at the lower and upper wall of the channel, with implications for the anisotropic nature of blood arteries. The findings contribute to a deeper understanding of fluid flow in anisotropic porous media and have potential applications in various engineering domains.

Permeability evaluation based on Nuclear Magnetic Resonance analysis for gas hydrate reservoir

Permeability (or hydraulic conductivity) is one of the most important parameters for analyzing hydraulic behavior of underground. For example, in the geotechnical engineering, permeability is necessary to calculate water inflow and draw down of water level during excavation, to predict the deformation time due to the consolidation, and to evaluate the barrier of the ground for radioactive waste disposal. In the petroleum industry, permeability is considered an essential parameter which is directly linked to the productivity of oil and natural gas. Therefore, predicting permeability using wireline logging or logging while drilling (LWD) is required during the assessment of the reservoir. Nuclear Magnetic Resonance (NMR) logging is performed at this point. Low-field NMR measurements are sensitive to the hydrogen proton, 1H, in liquid water but not to the 1 H bond in solid form, making it possible to obtain the bulk water volume. In addition, the hydrogen proton NMR- T2 (transverse or spin-spin) relaxation time distribution is used to infer pore-size information and to estimate permeability [1, 2]. The major methods used for estimating permeability, k, are the Schlumberger Doll Research (SDR) model and Timur-Coates (TC) model [3, 4]:
 Where fNMR is the NMR-estimated (effective) porosity. SDR model uses the averaged value of the T2 distribution plotted on log-scale of time and matches it to the experimental reference permeability with the fitting parameter a [mD/(ms)2]. The TC model seeks to differentiate between the fraction of free (mobile) fluid volume (FFV) and bound fluid volume (BFV) and estimates permeability with FFV/BFV ratio and the material constant c [m2/s2]. The permeability in the research and development of methane hydrate, which is expected to be a next-generation resource, has been estimated using above methods. Methane hydrate is an ice-like solid crystalline structure of water and methane molecules. Because hydrate is solid, NMR is not sensitive, the initial (effective) permeability can be estimated by NMR analyzer. On the other hand, A strong disconnect (up to 2 orders of magnitude) between NMR-based estimates of permeability with those determined from a laboratory study of pressure cores from the same reservoir has further cast uncertainty in the application of borehole NMR data in hydrate evaluation [5, 6]. Recently, authors provided comparisons between NMR-derived values and direct fluid flow estimates of permeability in naturally occurring hydrate-bearing sediment [7, 8]. On the basis of the NMR measurement for hydrate-bearing pressure core sediments, which were recovered from the Gulf of Mexico and Alaska North Slope, the following new hydraulic radius model was proposed [7].
 This equation estimates the specific surface based on the NMR signal and has been shown to successfully estimate the initial permeability of a hydrate reservoir by expressing a hydraulic radius model based on Kozeny's equation [9]. However, the proposed equation is not universal and has been found to overestimate for clayey and silty hydrate free sediment. This study summarizes the methods and parameters used to estimate permeability using NMR signals from hydrate-bearing sediment obtained from logging and laboratory tests for the Gulf of Mexico and Alaska North Slope. In addition, we reports parameters for predicting model for muddy sediments which was recovered from overburden of hydrate-reservoir in the Hyuganada sea in 2022 Japan [10, 11]. When using the hydraulic radius model to predict permeability of hydrate-bearing sediment, reasonable estimates can be obtained by setting the shape factor for grains Cs = 1/2 (for a circular grain) and the shape factor for the flow path cn = 4 (for the cylinder network), respectively. Although, for hydrate free muddy sediment, Cs = 1/3 for parallel plate grain shape and cn = 2 for the fracture network model matched its permeability. Furthermore, the conversion parameter from T2 relaxation time to the pore size for hydrate free muddy sediments r2 = 0.009 (mm/s) was confirmed based on the result of mercury injection capillary pressure analysis, which is lower than r2 = 0.0325 (mm/s) of hydrate-bearing sediments.

Inertial capture of aerosol particles using liquid bridges in cross flow

We investigate the inertial capture of aerosol particles, suspended in a laminar cross flow between parallel plates, by stationary cylindrical liquid bridges. We track the motion and fate of individual aerosol droplets (3–9 μm diameter) suspended in a flow moving across a single liquid bridge or two-bridge systems, using high-speed imaging under a microscope. First, we measure the capture efficiency by inertial impaction of an isolated liquid bridge collector as a function of the aerosol particles Stokes number and show that it agrees with the efficiency calculated for rigid particles moving in a potential flow past a solid cylinder. We then consider two-bridge systems, that is two parallel cylindrical collectors oriented perpendicular to the flow, but offset from each other. We investigate the effect that the upstream collector has on the effective capture efficiency of the downstream test collector, depending on the transverse offset and Stokes number. The offset is the relative displacement of the downstream collector normal to its axis and in the direction perpendicular to the freestream flow. For small values of the transverse offset, smaller than the radius of the collector, small (zero) effective efficiencies are measured for the test collector, due to a partial (complete) shielding effect by the upstream collector. The effective efficiency thus increases from zero with increasing transverse offset, above a threshold value for complete shielding. As the transverse offset increases further, effective efficiencies larger than the efficiency of an isolated bridge are measured for the test collector, showing enhanced capture due to the redistribution of particles moving past the upstream collector. The relative increase in the inertial capture efficiency is significant for Stokes numbers around (but below) unity, 0.45≲St≲0.9, with relative gains as large as approximately 50%. There is an optimum offset displaying maximum effective efficiency and larger offset values lead to a slight decrease in measured efficiencies. These results demonstrate the importance of the relative arrangement of individual collectors on the overall inertial capture efficiency of aerosol particles and suggest that an array of bridges in a slanted configuration (with optimal transverse offsets) could be used as a high-performance filtration system for aerosol particles.

Spatio-temporal measurement of density distribution in oscillatory boundary layer using phase-shifting interferometer

The objective of this study is to directly measure the acoustic density fluctuations of a gas confined between two parallel plates. For this purpose, we originally developed a phase-shifting interferometer, where a polarizing Mach–Zehnder interferometer was incorporated with a polarization camera. This enabled us to achieve a time resolution of 70 FPS in addition to the high-resolution measurement by the phase-shifting technique. The test beam passes through the two parallel plates of width 10 mm, where an acoustic field is generated using a loudspeaker that produces high acoustic pressures (up to 3000 Pa) at frequencies ranging from 0.5 to 5 Hz. In this work, we successfully measure the density fluctuations, which are otherwise difficult to obtain using conventional optical interferometers. Additionally, the experimental results are compared to the visco-thermal acoustic theory, where a good agreement was reached, affirming the effectiveness of this phase-shifting interferometer. Furthermore, using the proposed setup, we are able to measure and deduce the spatiotemporal variations of the pressure, density, and temperature without interfering with the acoustic field, which distinguishes it from measurement probes like thermocouples. This interferometer can be used to study more complex phenomena such as edge effects in thermoacoustic engines.

Bio-Convective Hartmann Flow of Couple Stress Hybrid Nanofluid Between Two Dilating Parallel Walls with Heat and Mass Transfer

The study of bio-convective flow of hybrid nanofluid attracted many researchers because of tremendous applications in the fields of biofuel biotechnology, enzyme-based biosensors and biomedical science. The present work addresses a comparative study of CuO/Al2O3-water and CuO-water nanoparticles on heat and mass transfer characteristics of the squeezing flow of MHD couple stress fluid between two parallel plates by suspending motile micro-organisms. An approximated numerical technique (Shooting method along with Runge-Kutta 4th order scheme) have been employed to analyse the system of coupled nonlinear ordinary differential equations. The above numerical investigations were carried out for various governing parameters such as couple stress parameter, Hartmann number, bioconvection Peclet number, squeezing parameter etc. The effects of these physical parameters are illustrated graphically over velocity components, temperature distribution, diffusion of concentration and density of motile microorganisms. In addition to this the numerical values of skin friction, the local Nusselt number and local Sherwood number are tabulated at the upper plate for CuO-water and CuO–Al2O3-water at the expanding and squeezing cases. The numerical results for temperature profiles are in good consistency with earlier research.

Dynamics of an oscillating cavitation bubble within a narrow gap

The oscillation characteristics of a bubble in a confined space have important implications for various applications, including liquid pumping and mixing and particle conveyance in microfluidic devices. In this study, analytical solution with second-order accuracy and numerical solution are derived for the free oscillation of a single bubble in a narrow gap between parallel plates, and the applicability to dimensionless initial values of the analytical solutions is clarified. Moreover, the free-oscillation characteristics of the bubble within the gap are explored and described and are compared to those of a bubble in an infinite liquid. The primary conclusions are as follows: (1) The inherent nature of bubble oscillation in a gap is significantly influenced by the bubble equilibrium radius, and the oscillation amplitude of different orders of the analytical solution is significantly influenced by the dimensionless initial radius. (2) The difference between the natural frequency and acoustic damping constant during bubble oscillation in a gap and those in an infinite liquid decreases with increasing equilibrium radius, and the value of the difference is not less than 50%. (3) Within the gap, the bubble radius, wall velocity, and wall acceleration of a bubble in a narrow gap predicted by the bubble equation dramatically differ from those of a bubble in an infinite liquid, with the differences increasing with the dimensionless initial radius, where the values of the differences in the acceleration can be as high as the order of 104%.

Effect analysis of spatial discrepancy of secondary emission yield on multipactor formation

Spatial discrepancy of secondary emission yield (SEY) is probably exacerbated by unexpected surface contamination or imperfect surface treatments for SEY suppression, which accordingly provokes increased multipactor risk in microwave devices. In this paper, an improved 2D2V nonstationary statistical modeling for multipactor of parallel plates capable of regarding all electron impacts and electron exchange at the periodic boundaries is developed to investigate the effect of this spatial SEY discrepancy on multipactor formation in microwave devices. The comparison with the 1D2V statistical modeling results, which is valid for the parallel-plate multipactor, proves the accuracy of this improved 2D2V statistical modeling and the necessity of appropriate boundary setting in multipactor analysis with spatial SEY variation. The modeling results also reveal that the multipactor establishment is dominated by the electron multiplication and the electron overflow in the high-SEY region, thus making the multipactor threshold strongly dependent on both the SEY property and the dimension of the region. Electron multiplication can be fully sustained in the high-SEY region when its size exceeds a critical dimension, which satisfies a scaling law (the sustaining dimension is proportional to the gap with the product of the RF frequency and the gap kept constant) and varies with the involved multipactor mode. This research will help in evaluating accidental multipactor risk caused by the surface contamination and the efficiency of multipactor prevention via applying surface treatments for SEY suppression to accessible regions.

Flow and heat transfer analysis of Couette and Poiseuille flow of a hybrid nanofluid with temperature-dependent viscosity and thermal conductivity

The purpose of this research is to quantify the influence of a number of independent parameters (−0.5≤α1,β1,β2≤0.5) on the heat transmission rate and the temperature of a nanofluid hybrid flowing between parallel plates. The linked nonlinear momentum and energy equations are solved using the regular perturbation method for two different cases resembling the plane Couette flow and Poiseuille flow. By combining engine oil with multiwalled carbon nanotubes (MWCNT) and aluminum oxide nanoparticles, a hybrid nanofluid is produced with wide-ranging lubricating and industrial applications. It has been found that the hybrid nanofluid can function as a coolant provided the relevant parameters are adjusted appropriately. It is demonstrated that these additives have a tendency to stabilise the thermal and the volume flow rate, hence decreasing randomization that is necessary for a good lubricant to function. The findings of the study indicate that β1 has a greater influence on temperature, while β2 has a stronger effect on velocity. In addition to the variable model, the results for the constant model have also been deduced, and the novel study demonstrates that the considered variable viscosity model tends to produce a more uniform temperature distribution.

Slip regime MHD 2-liquid plasma heat transfer flow with hall currents between parallel plates

The influence of the slip factor on the MHD 2-liquid heat transfer flow of ionized gases within a channel between two non-conducting plates with Hall currents is investigated theoretically. Slip conditions were used to obtain solutions for the velocity and temperature fields, as well as the heat transfer rates. The flow characteristics of the two liquids are studied for estimates of the leading parameters, for instance the magnetic parameter, Hall and slip factors, viscosity, density, height, electrical conductivity and the thermal conductivity ratios. It was observed that an upsurge in temperature in the two zones is caused by the thermal conductivity proportion. The rate of heat transfer coefficient diminishes up to a certain point, after that it starts to increase as the magnetic and Hall parameters increase

An Investigation of High-Z Material for Bolus in Electron Beam Therapy

Electron beams are frequently used for superficial tumors including: primary skin cancers, surgical scars, cutaneous lymphomas and benign conditions like keloids. However, due to electron beam characteristics the surface dose is 75-95% of the prescribed dose depending on beam energy thus requiring placement of bolus to augment surface dose. Various types of boluses; wet gauge/towel, superflab, superstuff, aquaplast, 3D printed plastics, customized dot-decimal bolus, thermoshield, brass and tantalum wire mesh are commonly used in clinics with variable difficulties that are not perfect. As majority of these devices do not snug to the skin contour and create air-gap that is known to produce significant dose perturbations creating hot and cold spot. The variable dosimetry has cosmetic implications and potentially increased risk of recurrence. A new cloth-like high-Z materials; Tungsten, (Z = 74) and Bismuth, (Z = 83) impregnated with silicone gel are now commercially available which is investigated in this study for bolus purpose. Commercially available, super soft silicone-gel based submillimeter thin Tungsten and Bismuth sheets were investigated for bolus properties in electron beams in the range of 6-12 MeV using 10x10 cm2 applicator. These materials were tested on various body contour for perfect snug without any air traps. Using parallel plate ion chamber measurements were performed in a solid water phantom on a medical linear accelerator machine. Depth dose characteristics were measured to optimize the thickness for surface dose to be 100% for selected electron therapy. Surface dose for a 10x10 cm2 cone for 6, 9, 12 MeV beams were measured to be 75.1%, 80.1% and 86.2%, respectively. Silicone-gel Tungsten and Bismuth sheets produce significant electrons thus increasing surface dose. Based on measured depth dose, our data showed that Tungsten sheets of 0.14 mm, 0.18 mm and 0.2 mm and Bismuth sheets of 0.42 mm, 0.18 mm and 0.2 mm provide 100% surface dose for 6, 9 and 12 MeV beams, respectively without any changes in depth dose except increasing surface dose. The new Tungsten and Bismuth based silicone-gel clothlike sheets are extremely soft but high tensile metallic bolus materials that can fit flawlessly on any skin contour without any air trap or variable thickness or spillage of the water as in conventionally used wet gauge. Only 0.2 mm thick sheets are needed for 100% surface dose without degradation of the depth dose characteristics. These materials are reusable and ideal for bolus in electron beam treatment. This investigation opens a new frontier in designing new bolus materials optimum for patient treatment.

Smart materials for experimental tectonics: Viscous behavior of magnetorheological silicones

Magnetorheological (MR) materials are a relatively new class of materials whose mechanical properties can be controlled by a magnetic field. In this work, we investigate the viscous behavior of MR silicones, i.e., mixtures of Polydimethyl Siloxane (PDMS) and carbonyl iron powder, for analog modeling purposes. The rheological properties were determined using a parallel plate rheometer equipped with a variable strength electromagnet. We measured viscosity, yield stress and response time of MR silicone samples in a wide range of strain rates as a function of concentration of carbonyl iron powder and applied magnetic field. We find that MR silicones in the unmagnetized state show a transition from Newtonian to shear-thinning behavior for increasing strain rates. In the magnetized state, MR silicones behave as Herschel-Bulkley, shear-thinning fluids. Viscosity, yield stress and power-law exponent increase as a function of carbonyl iron powder concentration and magnetic field. A simple experiment is presented to demonstrate how the rheology of the analog material can be easily controlled during an experimental run, a condition that is challenging to achieve with other materials commonly used in experimental tectonics.

Anomalous crystalline ordering of particles in a viscoelastic fluid under high shear

Addition of particles to a viscoelastic suspension dramatically alters the properties of the mixture, particularly when it is sheared or otherwise processed. Shear-induced stretching of the polymers results in elastic stress that causes a substantial increase in measured viscosity with increasing shear, and an attractive interaction between particles, leading to their chaining. At even higher shear rates, the flow becomes unstable, even in the absence of particles. This instability makes it very difficult to determine the properties of a particle suspension. Here, we use a fully immersed parallel plate geometry to measure the high-shear-rate behavior of a suspension of particles in a viscoelastic fluid. We find an unexpected separation of the particles within the suspension resulting in the formation of a layer of particles in the center of the cell. Remarkably, monodisperse particles form a crystalline layer which dramatically alters the shear instability. By combining measurements of the velocity field and torque fluctuations, we show that this solid layer disrupts the flow instability and introduces a single-frequency component to the torque fluctuations that reflects a dominant velocity pattern in the flow. These results highlight the interplay between particles and a suspending viscoelastic fluid at very high shear rates.

Dirac semimetal-assisted near-field radiative thermal rectifier and thermostat based on phase transition of vanadium dioxide.

The near-field thermal radiation has broad application prospects in micro-nano-scale thermal management technology. In this paper, we report the Dirac semimetal-assisted (AlCuFe quasicrystal) near-field radiative thermal rectifier (DSTR) and thermostat (DST), respectively. The DSTR is made of a Dirac semimetal-covered vanadium dioxide (VO2) plate and silicon dioxide (SiO2) plate separated by a vacuum gap. The left and right sides of DST are consisted of the SiO2 covered with Dirac semimetal, and the intermediate plate is the VO2. The strong coupling of the surface electromagnetic modes between the Dirac semimetal, SiO2, and insulating VO2 leads to enhance near-field radiative transfer. In the DSTR, the net radiative heat flux of VO2 in the insulating state is much larger than that in metallic state. When the vacuum gap distance d=100 nm, Fermi level EF=0.20 eV, and film thickness t=12 nm, the global rectification factor of DSTR is 3.5, which is 50% higher than that of structure without Dirac semimetal. In the DST, the equilibrium temperature of the VO2 can be controlled accurately to achieve the switching between the metallic and insulating state of VO2. When the vacuum gap distance d=60 nm, intermediate plate thickness δ=30 nm, and film thickness t=2 nm, with the modulation of Fermi level between 0.05-0.15 eV, the equilibrium temperature of VO2 can be controlled between 325-371 K. In brief, when the crystalline state of VO2 changes between the insulating and metallic state with temperature, the active regulation of near-field thermal radiation can be realized in both two-body and three-body parallel plate structure. This work will pave a way to further improve performance of near-field radiative thermal management and modulation.

Pulse electromagnetic flow of Jeffrey fluid in parallel plate microchannels

This paper investigates the pulse electromagnetic flow of a Jeffery fluid between parallel plate microchannels, where the pulse is considered as a relatively stable and common rectangular pulse. The Laplace transform and residue theorem are employed to derive the analytical solutions for the velocity and volumetric flow rate of the pulse electromagnetic flow. Graphical representations depict the effects of several important parameters, including the Hartmann number pulse width relaxation time and retardation time on them. The study findings demonstrate that the Hartmann number plays a vital role in the investigation of pulse electromagnetic flow. During the first half-cycle of the pulse electric field, the magnitude of the velocity amplitude increases and then decreases with the Hartmann number An interesting observation is that in the second half-cycle, larger Hartmann number values result in a decrease in velocity followed by a reverse increase. The profiles of velocity and volumetric flow rate exhibit oscillations over a relatively short period of time, then gradually reach a stable state with time and display periodic variation characteristics. Moreover, a larger pulse width leads to a longer variation period and more stable profiles of velocity and volumetric flow rate. For smaller Hartmann numbers the magnitude of the volumetric flow rate amplitude grows with the relaxation time and reduces with the retardation time However, as the Hartmann number increases, the influence of relaxation time and retardation time on the volumetric flow rate becomes significantly weakened, especially the retardation time

VISCOSITY AND HALL EFFECTS ON UNSTEADY MHD CASSON FLUID FLOW THROUGH A PARALLEL POROUS PLATE

This study investigates the temperature viscosity and Hall effects of a Casson fluid flow through a porous medium of a viscous incompressible fluid bounded by two parallel porous plates under the influence of thermal radiation and chemical reaction. A uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to variable pressure gradient. The transformed conservation equations are solved analytically subject to physically appropriate boundary conditions by using perturbation and Eigenfunction expansion techniques. The influence of a number of emerging non-dimensional parameters namely, variable pressure gradient parameter, suction parameter, radiation parameter and Hartman number are examined. It is observed that the primary velocity profile is increased with increasing temperature dependent viscosity while increase in Hall parameter leads to increase in secondary velocity profile of the flow.

Lorentz force influenced entropy generation in couple stress squeezed hybrid-nanofluid flow: Application to cardiovascular hemodynamics

The main aim of this numerical analysis is to demonstrate the effect of Lorentz force and viscous dissipation on the couple stress-squeezed hybrid-nanofluid flow between two parallel plates under the influence of external squeezing. A novel entropy generation effect is also included to describe the temperature distribution in the couple stress hybrid nanofluid regime. However, the couple stress hybrid nanofluid finds its abundant applications in the various fields of medicine and bio-engineering, particularly, in the removal of obstacles in the arteries, cancer treatment, etc. Inspired by these applications of couple stress hybrid nanofluids, the present problem is devised based on the squeezed parallel plate geometry. The unsteady nonlinear, coupled, two-dimensional, partial differential equations are constructed to disclose the flow and heat transport features. A robust Matlab-based Runge–Kutta fourth-order scheme with shooting technique is used to produce the similarity solutions of the governing equations through the deployment of suitable scaling transformations. Accordingly, it is noted that, enhancing Hartmann and Brinkman numbers increase the entropy generation. Increasing couple stress fluid parameter increases the thermal distribution. Velocity profile shows dual behavior for the raising couple stress fluid parameter. Bejan number increases with increasing Brinkman number. Entropy generation increases with enhancing nanofluid volume fraction. Conclusively, the uniqueness and novelty of the present investigation is the addition of magnetic Ohmic heating and viscous dissipation effects which generalizes the former studies and gives a more redefined numerical simulation of flow and heat transport features of couple stress hybrid nanofluid in the squeezing regime.