Secondary Velocity Research Articles

Blood Based Magnetohydrodynamic Casson Hybrid Nanofluid Flow on Convectively Heated Bi-Directional Porous Stretching Sheet with Variable Porosity and Slip Constraints

Abstract Fluid flow through porous spaces with variable porosity has wide-range applications, notably in biomedical and thermal engineering, where it plays a vital role in comprehending blood flow dynamics within cardiovascular systems, heat transfer and thermal management systems improve efficiency using porous materials with variable porosity. Keeping these important applications in view, in current study blood based hybrid nanofluid flow has considered on a convectively heated sheet. The sheet exhibits the properties of a porous medium with variable porosity and extends in both the x and y directions. Blood has used as base fluid in which the nanoparticles of Cu and CuO have been mixed. Thermal radiation, space-dependent, and thermal-dependent heat sources have been incorporated into the energy equation, while magnetic effects have been integrated into the momentum equations. Dimensionless variables have employed to transform the modeled equations into dimensionless form and facilitating their solution using bvp4c approach. It has concluded in this study that, both the primary and secondary velocities augmented with upsurge in variable porous factor and declined with escalation in stretching ratio, Casson, magnetic and slip factors along x- and y-axes. Thermal distribution has grown up with upsurge in Casson factor, magnetic factor, thermal Biot number and thermal/space dependent heat sources while has retarded with growth in variable porous and stretching ratio factors. The findings of this investigation have been compared with the existing literature, revealing a strong agreement among present and established results that ensured the validation of the model and method used in this work.

Hall effect on mixed convection MHD flow of nanofluid with clean, copper and Ag water through a vertical rotating channel

AbstractThis article aims to investigate the hall current consequences on the transfer of clean water containing silver in addition to copper nanoparticles suspended nanofluids through vertical rotating channel. Boussinesq approximation is taken into consideration. Exact analytical solutions of governing equations subject to physical boundary conditions are obtained using the techniques of non‐dimensionalization. The impacts of Grashof number, radiation parameter, Prandlt number, frequency parameter, magnetic parameter, Hall parameter, parameter of rotation and its effects on primary as well as secondary velocity and temperature profiles are presented graphically. We analyze the Hall effects and mixed convection in magnetohydrodynamic (MHD) flow of nanofluids through a vertical rotating channel, based on extensive research and applications. An analytical approach is used to derive the exact solution to this problem. A comparative study for silver and copper nanoparticles is made. A tabular solution for impacts of said parameters on convection rate and skin friction coefficient is also presented. This study is applicable for geophysical dynamics and engineering applications.

Heat transportation phenomena subject to Ellis fluid over a spinning body: A dynamics of trihybrid nanoparticles

AbstractThe boosting of base fluid thermal transport is a remarkable significance in the current research era, and numerous types of techniques are being utilized to achieve this goal. The mixture of nanoparticles inside the host fluid is responsible to improve base fluid thermal performance. The modified Buongiorno's nanofluid model is explored in the current study along with the significant trihybrid nanoparticle effect. The fundamental equations of the chosen flow model are transformed using a similarity transformation, and the succeeding equations are then resolved numerically using the discretization of Keller‐Box in MATLAB. The primary velocity profile is directly raised with large values of the Hartman number, unsteady, and Ellis's fluid parameters, while an inverse curves trend is reported in secondary velocity. The primary speed of fluid is significantly greater compared to di and mono‐hybrid cases, and this study reveals that optimal thermal transport is achieved against tri‐hybrid cases. The tri‐hybrid model has 9% improvement in Nusselt number when compared to single and two‐type nanoparticle fluid models.

Influence of magnetohydrodynamics and chemical reactions on oscillatory free convective flow through a vertical channel in a rotating system with variable permeability

This study investigates the impact of variable permeability as well as chemical reactions on the oscillatory free convective flow that passes parallel porous flat plates with fluctuating temperature and concentration in the presence of a magnetic field. A vertical channel is assumed to be rotating at an angular velocity [Formula: see text]. Periodic free stream velocity causes oscillations in one plate, while periodic suction velocity causes oscillations in the other plate. Complex variable notations are used to solve the governing equations. The perturbation technique is used to derive analytical expressions for the temperature, concentration, and velocity fields. In this study, various parameters were investigated in relation to mean velocity, mean temperature, mean concentration, amplitude, and phase difference. The study also examines the impact on secondary velocity, primary velocity, temperature, concentration, and heat transfer rate during transients. The outcomes are presented graphically for the physical parameters of the problem. The findings contribute to optimizing systems and improving efficiency in heat transfer, fluid dynamics, and environmental remediation.

Combined fluid and ferrofluid buoyancy force, heat absorption and non linear ferro-viscosity effects on ferro- hydrodynamics fluid flow in orthogonal porous surface

Mixed convection incompressible ferro-hydrodynamic (FHD) boundary layer fluid flow on vertical porous curvilinear orthogonal surfaces is examined in our present study in presence of combined fluid and ferro-fluid buoyancy force, nonlinear ferro-viscosity parameter, and heat absorption/generation effects. Design/Methodology/Approach: Types of Prandtl momentum and thermal boundary layer partial differential equations in a curvilinear system are converted into non-dimensional ordinary nonlinear differential equations (ODE) by introducing dimensionless velocities, temperature functions and similarity variable. Missing initial conditions are found by shooting method and solving the system of nonlinear ODEs by Runge-Kutta integration scheme of order six. With the help of MATLAB, the numerical solutions are graphically displayed in the forms of primary velocity profile, secondary velocity profile, and temperature profile. Three types of magnetic nano-ferrofluid are considered such as water-based ferrofluid (Taiho W-40), Hydrocarbon based ferrofluid (EMG-901) and kerosene-based ferrofluid (C1-20B) whose Prandtl numbers are 44.3, 79.3 and 128 respectively shown in Table 1. For kerosene based ferro-fluid, Table 3 presents the coefficient of skin friction and heat flux. Finding: The effects of combined fluid and ferrofluid buoyancy forces, nonlinear ferro-viscosity parameter, suction/injection, and heat absorption/generation parameters on the velocity and temperature profiles are investigated. Our physical interest is to calculate the local shearing stresses and the local heat flux at the surface. Finally, we have made comparisons of the results which are highlighted the validity of our numerical calculations adopted for the presence study.

A heterogeneous ultrasound open scanner for the real-time implementation of computationally demanding imaging methods.

Ultrasound open scanners have recently boosted the development and validation of novel imaging techniques. They are usually split into hardware- or software-oriented systems, depending on whether they process the echo data using embedded FPGAs/DSPs or a GPU on a host PC. The goal of this work was to realize a high-performance heterogeneous open scanner capable of leveraging the strengths of both hardware and software-oriented systems. The elaboration power of the 256-channel ultrasound advanced open platform (ULA-OP 256) was further enhanced by embedding a compact co-processing GPU system-on-module (SoM). By carefully avoiding latencies and overheads through low-level optimization work, an efficient PCIe communication interface was established between the GPU and the processing devices onboard the ULA-OP 256. As a proof of concept of the enhanced system, the high frame rate color flow mapping technique was implemented on the GPU SoM and tested. Compared to a previous DSP-based implementation, higher real-time frame rates were achieved together with unprecedented flexibility in setting crucial parameters such as the ensemble length (EL). For example, by setting EL=64 and a continuous-time high-pass filter, the flow was investigated with high temporal and spatial resolution in the femoral vein bifurcation (frame rate = 1.1 kHz) and carotid artery bulb (4.3 kHz), highlighting the flow disturbances due to valve aperture and secondary velocity components, respectively. The results of this work promote the development of other computational-expensive processing algorithms in real-time and may inspire the next generation of ultrasound high-performance heterogeneous scanners.

Mathematical theory and CFD solutions for internal convective cooling of gas turbine blades highlighting the effects of rotation

A quasi-one-dimensional mathematical theory is developed for determining the effects of rotation on the fluid flow and heat transfer in a cooling channel within a rotating gas turbine blade. The three-dimensional intricacies in the solutions of the same problem are captured through accurate computational fluid dynamic simulations. The derived analytical closed-form solutions predict the amount by which the relative total temperature of the coolant changes as a result of rotation. It is shown that such changes due to rotation are significant proportion of the change of coolant temperature due to heat transfer. The computed spatial evolutions of the primary velocity field, secondary velocity field and the force fields are presented as the coolant progresses from the inlet to the outlet so that the complexities and subtleties are exposed to a high degree of visualizability. Detailed considerations to various components of the centrifugal, Coriolis and pressure forces are given. The flow field is shown to depend strongly on whether the coolant moves in the spanwise outward or inward direction. The three-dimensionality of the flow field is reflected in complex circumferential variations of the blade temperature and the internal heat transfer coefficient. When the effects of the x–component of the Coriolis force interacts non-linearly with the effects of the z–component of the centrifugal force and a drastic x-gradient in fluid density due to a thin thermal boundary layer, then the primary velocity profile may exhibit great complexity, including flow separation. The present paper thus captures the strong, non-linear, two-way coupling between the fluid dynamics and heat transfer in the internal convective cooling occurring in a channel within a rotating gas turbine blade. Based on about 100 three-dimensional computational fluid dynamics simulations, new heat transfer correlations are developed for average Nusselt number for a rotating channel that will be of practical use.

A numerical analysis of the rotational flow of a hybrid nanofluid past a unidirectional extending surface with velocity and thermal slip conditions

Abstract This work inspects 3D magnetohydrodynamic hybrid nanofluid flow on a permeable elongating surface. The emphasis of this paper is on the study of hybrid nanofluid flow within a rotating frame, taking into account the simultaneous impact of both thermal and velocity slip boundary conditions. The chosen base fluid is water, and the hybrid nanofluid comprises two nanoparticles Cu \text{Cu} and Al 2 O 3 {\text{Al}}_{2}{\text{O}}_{3} . The effect of the magnetic and porosity parameters is taken into account in the momentum equation. The thermal radiation, Joule heating, and heat source are considered in the energy equation. Using a similarity system, we transform the PDEs of the proposed model into ODEs, which are then solved numerically by the bvp4c technique. The magnetic field shows a dual nature on primary and secondary velocities. Enrich magnetic field decreases the primary velocity and enhances the secondary velocity. The rotation parameter has an inverse relation with both velocities. The temperature profile amplified with the escalation in heat source, magnetic field, rotation factor, and Eckert numbers. The skin friction is boosted with magnetic parameters while the Nusselt number drops.

Investigation of micropolar dusty fluid flow in a rotational frame with magnetic field: A meshless radial basis function pseudospectral approach

AbstractRotational flow has numerous applications across a wide range of fields, including industrial processes for mixing, pumping, and processing materials, geophysical fluid dynamics for studying the Earth's atmosphere and oceans, aerospace engineering for designing and testing aircraft and spacecraft, medical imaging for creating detailed images of the human body, and environmental engineering for studying the transport of pollutants in water and air. In rotational flow, pumping power is an important parameter that measures the amount of energy required to maintain the flow of the fluid in a rotating frame. It is significant because the presence of the Coriolis force and other rotational effects can substantially alter the fluid dynamics, making it difficult to maintain a steady flow. The present study deals with the flow of micropolar dusty fluid in a rotating frame under the influence of the magnetic field, applied transversely to the flow in a horizontal channel. The fluid is induced to flow between two parallel plates by the movement of the upper plate and a constant pressure gradient. A meshless radial basis function pseudospectral approach is employed to derive a set of partial differential equations that determine the primary and secondary velocity profiles of the fluid, as well as the particle and microrotation velocities and temperature distribution. The pumping power required to sustain the flow in the absence of a pressure gradient is also calculated based on these velocity profiles. The findings provide valuable insights into the behavior of micropolar dusty fluids in a rotational channel and can potentially inform the design of industrial processes involving such fluids.

Mathematical modeling and experimental investigation of pressure characteristics inside the pilot stage of the deflector jet servo valve considering secondary jet velocity distribution

Mathematical modeling and experimental investigation of pressure characteristics inside the pilot stage of the deflector jet servo valve considering secondary jet velocity distribution

Hydromagnetic Turbulent Flow in Porous Media Over a Stretching Surface in a Rotating System with Heat

This study investigates the combined effects of magnetic fields, buoyancy forces, porosity, rotation, and Joule’s heating on fluid flow and heat transfer dynamics. The analysis is performed using a numerical approach, with the system oriented along three axes: the z-axis aligned with the plate, the y-axis perpendicular to the plate, and the x-axis orthogonal to the y-z plane. An infinite plate extends along the x and z axes, with a uniform transverse magnetic field applied parallel to the y-axis. By employing the finite difference method in MATLAB, we explore how various dimensionless parameters influence temperature and velocity profiles. Our findings reveal that an increase in the local temperature Grashof number enhances primary velocity while reducing secondary velocity near the fixed end. Temperature profiles show a decrease near the plate, increasing further away. The study also highlights that a higher Joule heating parameter leads to elevated primary velocity and temperature profiles but diminishes secondary velocity. Additionally, increasing rotational parameters is observed to decrease both primary and secondary velocities while augmenting temperature profiles near the plate. These results underscore the significant role that magnetic fields, rotational effects, and Joule heating play in modulating fluid flow and thermal behavior. The insights gained from this study can inform the design and optimization of engineering systems where control of velocity and temperature profiles is critical.

Effects of structural configuration on perforation/spalling damage and secondary fragment velocity of reinforced concrete slabs subjected to close-in explosion

Reinforced concrete (RC) slabs are vulnerable to localized damage from close-in TNT explosions, suffering perforation and extensive spalling damages that generate high-velocity secondary fragments posing severe risks to nearby facilities and personnel. Current numerical methods such as the Finite Element Method (FEM) face challenges in accurately predicting fragmentation due to mesh distortion caused by large deformations and discontinuities, underscoring the need for enhanced modelling techniques. As a result, although numerous studies have numerically investigated how structural configurations influence RC slab damage under blast loads, the issue of mesh distortion and element erosion in FEM has led to the inability in reliably predicting the associated threats from high-velocity fragments. This study numerically investigates the influences of structural configuration (e.g., concrete strength, reinforcement ratio and layout, dimensions of slabs, and concrete cover depth) on the perforation/spalling area and fragment ejecting velocity of one-way RC slabs subjected to close-in explosions through an ALE-FEM-SPH numerical model, which has been demonstrated effective and reliable in the authors’ previous studies. The results indicate that concrete strength and slab thickness most significantly affect both the damage and fragment characteristics, while the slab's width-to-height ratio, reinforcement ratio, and layout, have less influence, particularly on fragment velocity. Empirical equations derived from extensive numerical data are provided to help engineers and security personnel quickly evaluate the blast effects on RC slabs. The accuracy and robustness of the proposed formulae, which can be straightforwardly used to predict blast fragments of reinforced concrete slabs, have been statistically evaluated and the proposed formulae demonstrate satisfactory precision, with less than 20 % error in estimating damage area, maximum fragment velocity, and total kinetic energy of fragments.

Couette flow of viscoelastic dusty fluid through a porous oscillating plate in a rotating frame along with heat transfer

AbstractUsually, suction/blowing is used to control the channel's fluid flow, which is why this worth‐noting effect is considered. The fluid velocity is considered along the x‐axis due to the oscillations of the right plate. The thermal effect on the flow due to the heated right plate is also considered. The fluid and dust particles have complex velocities due to the rotation, which are the sum of primary and secondary velocities. To convert the aforementioned physical phenomenon into mathematical form, partial differential equations are used for modeling the subject flow regime. Appropriate nondimensional variables are employed to nondimensionalize the system of governing equations. With the assistance of assumed periodic solutions, the system of partial differential equations is reduced to a system of ordinary differential equations which is then solved by the perturb solution utilizing Poincare–Lighthill perturbation techniques. The engineering interest quantities, the Nusselt number, and skin friction are also determined. The impact of various parameters on skin friction, viscoelastic fluid, and dust particle velocity profiles is also investigated. It is worth mentioning that suction controls the boundary layer to grow unexpectedly, even in the resonance case. The obtained solution is also valid in the case of injection. The radiation parameter, Grashof number, and second‐grade parameter cause a decrease in skin friction as their values increase. On the other hand, the suction, rotation, magnetic, dusty fluid, and Reynolds numbers cause a rise in skin friction.

Insight into the magnetohydrodynamic flow of CNT-based nanofluid through a horizontal porous channel: Nanoparticle passive control

This work aims to investigate the CNT-based nanofluid flow in a rotating horizontal channel. The fluid is considered to be thermally radiative, and Hall effect is expected to be dominant in the fluid flow. The Darcy-Forchheimer model is used to describe the flow of a porous material. The usual approach of transformation converts the nonlinear partial differential equations (PDEs) into a reduced set of ordinary differential equations (ODEs). To solve the created model, the MATLAB bvp4c procedure is used. The effects on temperature, speed and volume percentage of nanotubes of the key flow parameters are clearly indicated by the graphs. Energy strength, and surface drag force are also calculated and summarized. The result shows that both primary and secondary fluid velocities with MWCNTs are decreased with the inertia parameter. In addition, a rise in thermophoresis occurrences leads to an increased temperature of nanofluids, whereas an increase of Brownian diffusion parameter leads to lower nanofluid temperature.

Stability and combustion characteristics of dual annular counter-rotating swirl oxy-methane flames: Effects of equivalence and velocity ratios

An experimental study was carried out to investigate flow/flame interactions, stability, combustion, and emissions properties of CH4/O2/CO2 stratified flames stabilized on a dual annular counter-rotating swirl (DACRS) burner for gas turbine combustion applications. The effects of two targeted parameters, namely equivalence ratios (for primary - ϕp, secondary - ϕs, and global - ϕg streams) and velocity ratio (Vr = Vp/Vs: primary to secondary stream inlet velocity ratio), are studied at fixed volumetric oxygen fraction (OF) in the oxidizer mixture (O2 + CO2) of both primary and secondary streams of 34 % at fixed Vp of 5 m/s. The experimental results indicated that no flame flashback was recorded in the domain of any operational ϕp up to stoichiometric operation of the secondary stream (ϕs = 1.0). At near stoichiometric operation of the primary stream, the main secondary flame can persist in extremely lean conditions (ϕs = 0.45 @ Vr = 3), thereby extending the thresholds of flame blowout. Moreover, raising ϕp from 0.4 to 1.0 results in significant reduction of ϕs at blowout from 0.595 to 0.456, corresponding to reducing the combustor ϕg at blowout from 0.577 to 0.499. At lower ϕp, the oxy-methane flame tends to lift and extinguish earlier.

Shear‐driven flow of an ionic fluid in a narrow vertical channel under a Hall electric field

AbstractThis paper focuses on demonstrating the shear‐driven convective flow of an ionic optically thin fluid in a narrow channel formed by two vertical parallel plates subject to a Hall electric field. The Hall electric field induces Hall currents, amending the flow dynamics of the ionic fluid. The setup involves a stationary left wall and a right wall that either undergoes impulsive motion (IM) or accelerated motion (AM), which initiates the fluid flow. A unified closed‐form solution for flow‐regulating equations is derived by harnessing the Laplace transform (LT) approach. The upshots of cardinal parameters on the velocity components and temperature distributions, shear stresses, and rate of heat transfer (RHT) are elucidated via graphics for both IM and AM scenarios. The graphs reveal that an intensification in the Hall parameter notably boosts the velocity components in both IM and AM cases. The primary and secondary velocities are consistently higher for IM than AM. The magnitude of shear stresses at the moving wall is always greater for IM than AM. Additionally, the shear stresses at the moving wall are notably greater for IM than AM, and the RHT at the moving wall reduces as the radiation parameter amplifies. The significant findings of this research have potential applications in electromagnetic propulsion systems, like plasma or ion thrusters, commonly employed in propelling spacecraft.

Wing-to-Wall Distance Effect On The Large-Scale Turbulent Structures Interacting With A Wall

We experimentally investigate the effect of the wing-to-wall distance, also called ground clearance, on the three-dimensional flow generated by a wing at a 4° angle of attack and a chord Reynolds number of 1400. We perform 3D velocity measurements using Particle tracking velocimetry to characterize the wake downstream of the wing, evaluate the evolution of the intensity and the size of the wingtip and secondary counter-rotating vortices, and finally compute the aerodynamic coefficients using momentum balance equations. We extended the control volume method for drag and lift calculation to the case where the transverse plane downstream of the wing does not contain the whole wake. The secondary flow's vorticity isocontours and velocity vectors show a decrease in the downwash and vortex size with the ground clearance ratio (i.e., as we approach the ground). The computation of the circulation shows that this latter decays rapidly streamwise as we get closer to the wall, indicating a dissipation of the kinetic energy contained in the trailing vortices. The aerodynamic coefficients' results based on the control volume method show that the tested wing manifests a two-force regime evolution of the drag coefficient with the ground clearance ratio, as it first decreases when moving far from the ground before increasing as we move farther from the ground. A noteworthy high lift is generated when too close to the ground. Further application of the extended control volume method on DNS data is needed to validate the method.

Fragment velocity response of grouted and unreinforced concrete masonry walls subjected to blast loading

Very few methods are available for predicting the secondary fragment velocity and secondary fragment production of grouted and unreinforced concrete masonry unit (FGUR CMU) walls when subjected to blast loading. A novel energy-based methodology is developed that calculates the secondary fragment velocity of an unreinforced fully grouted concrete masonry unit (CMU) wall under blast loading. The computationally efficient, engineering-level methodology was originally derived for fragment velocity calculation of unreinforced ungrouted CMU walls. Existing approaches often require large computational resources or fail to predict secondary fragment velocity accurately; this approach calculates fragment velocities with minimal computational effort. The applicability of this analytical model to unreinforced fully grouted CMU walls is discussed. The selection of a resistance function and assumptions about fragment behavior are examined. Velocity calculations throughout wall fragmentation are compared to velocities from quarter-scale and full-scale experiments and reasonable agreement is observed.

The Effect of Freeze-thaw on Mechanical and Ultrasonic Properties of Hungarian Oolitic Stones

The freeze-thaw process is a weathering phenomenon that occurs in rocks and stones when water enters small cracks and pores within the stone. When the temperature drops below freezing, the water inside the rock expands as it freezes, exerting pressure on the rock from within. In this study the effect of freeze thaw on mechanical parameter uniaxial compression strength (UCS) and ultrasonic pulse velocity (UPV) of 47 oolitic samples were considered. At first, capillary absorption for cylindrical and prismatic oolitic samples were measured and then freeze-thaw experiment with 23 cycles were applied to the samples. UPV of samples before and after freeze-thaw was analysed by two ultrasonic devices including Geotron and Pundit. It was observed that freeze thaw decreases primary velocity (Vp) and secondary velocity (Vs) by around 20 and 7% respectively. However, average UCS of 1.6 MPa indicates strength decrease of samples, which represent negative effect of pore expansion due to freeze thaw on strength parameter of samples.

A semi-analytical solution of the magnetohydrodynamic blood-based ternary hybrid nanofluid flow over a convectively heated bidirectional stretching surface under velocity slip conditions

This work inspects the thermal transportation of the magnetohydrodynamic Casson trihybrid nanofluid flow over a convectively heated bidirectional elongating sheet. The flow is considered as three dimensional passing over the sheet, which is placed in a porous medium. The effects of thermal radiations and space- and thermal-dependent heat sources are used in energy equations, while magnetic effects are used in momentum equations. Appropriate variables have been used to convert the modeled equations into a dimensionless form, which have then been solved using the homotopy analysis method. In this work, it is uncovered that both the primary and secondary velocities are weakened with an upsurge in porosity and magnetic factors. The thermal transportation is augmented with growth in thermal- and space-dependent heat source factors and the thermal Biot number. The convergence of the method used in this work is ensured through ℏ-curves. The results of this investigation have also been compared with the existing literature with a fine agreement among all the results that ensured the validation of the model and method used in this work.