Couple Stress Research Articles

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.

Impact of Heat Transfer and Inclined MHD on A Non-Uniform Inclined Asymmetrical Channel with Couple Stress Fluid Through A Porous Medium

The goal of this study is to investigate the effects of heat transfer on a non-uniform inclined asymmetrical channel with couple stress fluids via a porous medium using incline magnetohydrodynamics. The governing equation is studied while using low Reynolds approximations and long-wavelength assumptions. Mathematical expressions for (pressure gradient), (temperature), (axial velocity), (heat temperature coefficient), and (stream function). A precise set of values for the various parameters in the present model has been used. The mathematical expressions for axial velocity, stream function, pressure gradient, and pressure rise per wavelength have been derived analytically. "MATHEMATICA" is used to present the computational results in the form of graphs. It has been noticed that both the pressure rise and the pressure gradient decrease with the rise of the inclination magnetic field angle and Darcy number, while as the Grashof number increases, the pressure gradient reduces and the pressure also increases. According to this study, the heat transfer coefficient and temperature rise when the Brinkman number and the Hartman number are up. As the Hartman number and couple stress increase, the incidence of trapped boluses diminishes in size and vanishes in the direction downstream. The bolus size can also be increased by raising the non-uniform channel's Darcy number.

Experimental investigation on seismic behavior of the precast shear wall systems with different connection methods under the coupling action of axial tension and cyclic horizontal load

The grouting sleeve connection and lapped steel bars connection are widely used for the connection, while they often require skilled workers, concealed work, and high installation accuracy, and can be expensive and cause significant damage to horizontal construction joints under earthquakes or extreme winds. To address these issues, based on the lap-spliced connection, the angle steel connectors were installed on the precast shear walls and foundation beams to improve the shear resistance and connection performance of horizontal construction joints and reduce construction issues. In practice, shear walls in high-rise structures may experience the coupling action of axial tension and cyclic horizontal load under strong earthquakes or extreme winds, resulting in an unfavorable state of tension bending or tension shear coupling stress for the shear wall systems. As the height-width ratio of these structures increases, there is a significantly increased possibility of shear wall structures experiencing tension bending or tension shear. In this study, five shear walls with different connection methods were manufactured and tested under the coupling action of axial tension and cyclic horizontal load. And the results suggested that the shear resistance of precast concrete shear walls at the horizontal construction joint significantly influenced their seismic performance and concrete damage when subjected to axial tension and cyclic horizontal loads. The precast shear wall system that utilized lapped steel bars and angle steel connectors for connections exhibited the best seismic performance. Additionally, the continuous horizontal construction joint formed by integral prefabrication (containing the edge components) slightly reduced the seismic behavior of the novel precast shear wall system utilizing lapped steel bars and angle steel connectors. The new precast shear wall system utilizing angle steel connectors has the potential to be an effective means of providing seismic resistance in high-rise structures that are subjected to the coupling action of axial tension and cyclic horizontal load.

Investigations on the compression-shear coupled stress waves propagating in heterogeneous rock

In order to investigate the heterogeneous responses in complex rocks, a compression-shear coupled constitutive relationship with four coupled parameters is established and a generalized wave equation is obtained. Based on the generalized self-consistent theory, the approach to determine the four coupling parameters related to local stress and strain state in the heterogeneous rock with multiphase components is proposed. A meso finite element model (meso-FEM) is employed to calibrate the calculation process according to four load paths. Based on the generalized wave equation, three characteristic wave velocities of 3-D plane waves are derived to describe the compression-shear coupled effect on wave propagation. These wave velocities (e.g. the primary wave and secondary wave) are different from those of the conventional compression wave and shear wave due to the coupled effects. As an example, the theoretical method is further employed to investigate wave velocities in the heterogeneous granular medium due to particle rotation. It indicates that wave velocities in the looser medium are related to local rotation and local strain. Particle rotation has significant effects on the wave velocities, which causes severe heterogeneity and compression-shear coupling effect in particle material. Both the heterogeneous distribution of internal materials and particle rotation affect wave velocities. The results provide a profound theoretical explanation for the heterogeneity of rock and are expected to provide a comprehensive understanding of the physical mechanism of the effect of heterogeneity on wave velocity.

Numerical Study on Hydromagnetic Oscillating Flow of Couple Stress Nanofluid in a Porous Channel with Cattaneo Christov Heat Flux

Numerical Study on Hydromagnetic Oscillating Flow of Couple Stress Nanofluid in a Porous Channel with Cattaneo Christov Heat Flux

Couple stress behaviors of nonlinearly radiating hybrid nanofluid over convectively heated Riga plate exploring thermophoretic and Brownian impacts

The endeavor toward exploring the significant impacts of modified Hartmann number and the couple stress facts over the nonlinearly radiating hybrid nanofluid flow inclusive of thermophoretic and Brownian effects over the Riga plate subjected to the Newtonian Heating has been analyzed. The model was developed by incorporating the above-mentioned physical aspects. Numerical solutions have been drawn through the RK Feldberg scheme using efficiently modified Matlab code. The outcomes based on the parametrical analysis were portrayed graphically and the key values-based fallouts were tabularized comparatively with traditional nanofluid behavior in those similar conditions. As the modified Hartmann number exerts favorable sustenance, the couple stress exhibits the impeding effects in fluidity, thermal and mass transference deeds. Yet another constructive upshot for hybrid nanofluid’s performance over traditional fluids even in such thought-provoking physical conditions.

Mode decoupling in interlaminar fracture toughness tests on bimaterial specimens

The present work has a two-fold objective: (i) to critically review the methods for fracture mode decoupling in unconventional laboratory specimens, such as the asymmetric double cantilever beam (ADCB) specimen; and (ii) to propose mode decoupling conditions and associated specimen design formulae to obtain pure fracture modes when bimaterial specimens are tested in ADCB and asymmetric end-notched flexure (AENF) configurations. In the first part of the paper, the literature on fracture mode decoupling is reviewed to shed light on some controversial points. We start with discussing various pure-mode conditions suggested by different authors and continue with the simplest case of the bimaterial joint. Our review also considers complex cases, such as the presence of bending–extension coupling or residual (hygrothermal) stresses. In the second part of the paper, bimaterial specimens loaded in ADCB and AENF test configurations are investigated. Employing energetically orthogonal mode decomposition, Engesser–Castigliano’s theorem, and the laminated beam theory, we illustrate specimen design criteria enabling to obtain pure fracture modes. The obtained specimen design formulae are validated through finite element analyses.

Couple stress effects on the MHD oscillatory flow in a fluid‐saturated porous layer

AbstractIn this paper, the oscillatory flow of hydromagnetic couple stress fluid‐saturated porous layer with inhomogeneous wall temperatures is studied. The flow is modeled using the modified Darcy equation. The fluid is subjected to a transverse magnetic field and the velocity slip at the lower plate is taken into deliberation. The governing coupled partial differential equations of the flow are transformed to coupled ordinary differential equations and are solved analytically. The impact of the physical parameters such as the Grashof number, Prandtl number, Darcy number, Hartmann number, and couple stress parameters on velocity profiles, temperature, rate of heat transfer, and skin friction are emphasized. The velocity field increased as either the Grashof number, the Darcy number, the suction/injection parameter, and Prandtl number increased nevertheless reverse growth can be seen by increasing the Hartmann number and the couple stress parameter. The temperature field in the channel increases with increasing the suction/injection parameter and Prandtl number but a conflicting development can be seen with increasing the oscillation amplitude. It is interesting to note that skin friction increases on both channel plates as injection increases on the heated plate.

A fractional model of magnetohydrodynamics Oldroyd-B fluid with couple stresses, heat and mass transfer: A comparison among Non-Newtonian fluid models

The present article aims to extend some of the already existing fluid models to a large class of fluids namely, “Oldroyd-B couple stress fluid (OBCSF)”. The main focus of the present work is to combine the existing fluid models in ordered to get a new class of fluid. The unsteady magnetohydrodynamics (MHD) Oldroyd-B fluid (OBF) with couple stresses, porosity, heat and mass transfer is considered in the present analysis. The Oldroyd-B couple stress fluid is assumed to flow in channel. The classical model is fractionalized by considering Atangana-Baleanu (AB) operator in ordered to highlight the memory analysis. To develop closed form solutions the combined (Laplace + Fourier) integrals have been used. The results obtained are portrayed through graphs for all pertinent flow parameters which involved in the present dynamic model. Moreover, the impact of AB time fractional parameter is investigated graphically on flow, temperature and concentration distributions exploiting MATHCAD software. Secondly, for better understanding the present solutions of Oldroyd-B couple stress fluid (OBCSF) are reduced to Odroyd-B fluid (OBF) without couple stresses, Maxwell solutions, Couple stress solutions and Newtonian viscous fluid solutions and the results have been compared for classical and fractional order derivatives. In addition to this a limiting case is carried out by our solutions to already published work which verify our solutions. In addition to this during the analysis we noticed that the flow heat and concentrated get lowered for the escalating numerical values of AB fractional derivatives. Similarly, it is also noticed that the velocity in channel accelerated with the increment of numeric values of pressure, porosity, thermal buoyancy and relaxation time parameter. In the same manner temperature and concertation profiles gets low with the higher values of Prandtl number, Reynold number and fractional operator. Finally, skin friction for momentum equation, Nusselt number for temperature and Sherwood number for concentration have been calculated and given in tabular forms.

A Study on the Differences in Integrated Classification of Work-Family Balance and Parenting Stress in Dual-income Couples

A Study on the Differences in Integrated Classification of Work-Family Balance and Parenting Stress in Dual-income Couples

Moving Load Analysis of Laminated Porous Micro Beams Resting on Elastic Foundation

This research highlights dynamic displacements of laminated porous micro beams resting on elastic foundation under moving load. In the constituted equation of laminated micro scaled beam, the modified coupled stress theory is used in order to determine the size effect. Each layer is considered as identical and porosity distribution and assumed as uniform. Lagrange technique is applied in achieving governing equations, and Ritz method within algebraic polynomials is used for solution. For dynamic solution steps, Newmark average acceleration method is used within time domain. Influences of porosity coefficients, length scale parameter, foundation parameter, order of laminas, fiber orientation angles on dynamically deflections of laminated micro beam are investigated.

Oscillatory Flow of Couple Stress Fluid Flow over a Contaminated Fluid Sphere with Slip Condition

This research paper aims at finding the analytic solution for an oscillatory flow of couple stress fluid flow over a contaminated fluid sphere, filled with a couple stress fluid which is considered with interfacial slip on the boundary. The stream functions and drags related to the findings were analytically obtained. The special cases as a result of this are deduced for drag force which satisfies with the available data mentioned in the literature. The numerical values that were obtained are represented in both tabular and graphical forms for ease of representation. It has also been observed that in the case of viscous fluid, there is an inverse relation between real drag, slip parameter and viscosity ratio. It was also found that, there is a direct relation between imaginary drag, slip parameter and viscosity ratio respectively. For instance, in the case of the couple stress fluid, at lower values of the couple stress parameter there is a reduction in real drag, and an increase in imaginary drag respectively. These findings can result in future research considering body forces and other non-Newtonian fluids

Influence of Hall current & Lorentz force with nonlinear thermal radiation in an inclined slip flow of couple stress fluid over a Riga plate

Partially ionised fluids subject to an external magnetic field results in a completely different dynamical behaviour. Very few studies are conducted to explore the fascinating properties of Hall current and Ion slip in fluid flows. Flow over a Riga plate with MHD Ion and Hall currents, nonlinear thermal radiation is still rare. We aim to analyse the inclined stagnation point slip flow of Couple Stress fluid over a stretched horizontal Riga plate to close this gap. The flow problem is modelled using Navier stokes theory along with energy conservation and then principal partial differential equations are converted into ordinary differential equations. The governed system is solved mathematically by numerical technique RK Fehlberg method. The behaviour of fluid is described through graphs including fluid’s motion and energy. Local surface skin friction coefficients and local heat and mass flux at surface are the concerned physical magnitudes which are described through graphs and tables and are highly recommended in practical solicitations in numerous production plants and manufacturing workshops. Thermally radiative MHD flow with Ion Hall currents are broadly used in thermal controlling systems, spectro scopy, microchip technology, Magnetohydrodynamic energy conversion campaigns, exploration and expansion for high & low efficiency release, power-driven & power generation structures, MHD accelerations & thrusters, and drift regulator in hypersonic and automobiles.

Cracks propagation characteristics of double-hole delay blasting in soft-hard composite rock mass

By researching the distance between blasthole and interface of soft-hard rock strata, as well as the time of delay detonation, blasting effect of the rock mass will be more controllable. Firstly, validity of numerical method was authenticated from three angles: blasting coupled stress field, ratio of crushing zone radius to blasthole radius, and crack network state. Under the condition of soft-hard rock strata, numerical model of double-hole blasting was established by using PFC2D. Then delay blasting experiments were carried out under different relative positions of blasthole and interface. Ultimately, results were analyzed from three perspectives: crack network, crack quantity and rock fragment. Results show that: (1) When detonated in hard rock, if between interface and blasthole distance is greater than twice crushing zone radius, the closer blasthole is to the interface, the more obvious the “hook” phenomenon between the two blastholes is. With increasing delayed initiation time, “hook” phenomenon will weaken or even disappear. (2) Based on the crack information initiated in hard rock, the law of crack number varying with thickness of hard rock and delay time is obtained. (3) For initiation in hard rock, crack extension range is large, but less fragments are formed. The law is opposite to that initiation in structural plane and soft rock. Fragmentation area increases exponentially with increasing soft rock thickness, and exponential function is obtained.

Impact of Couple Stress with Rotation on Walters, B Fluid in Porous Medium

: With the help of a couple stress model and a porous material, this research examines peristaltic flow of Walter's B fluid through an asymmetric channel. For the balance of mass, motion, trapped phenomena, velocity distribution, and pressure gradient, the constitutive equation is modeled. In the flow analysis, a wavelength with a low Remolds number assumption is chosen, and the perturbation method is used to provide an accurate solution. Gained knowledge includes the impact of various parameters on the confined phenomenon's velocity distribution and pressure gradient. The set of numbers presented here is a graphic analysis of these parameters.

Impact of viscous dissipation and entropy generation on cold liquid via channel with porous medium by analytical analysis

In the current investigation, it is examined numerically entropy generation (EG) on inherent irreversibility motion of couple stress cold liquid with porous medium via Horizontal channel in presence of viscous dissipation. Present work was studied heat generation on couple stress liquid with porous channel. This work considerable importance in many industrial applications like “Control Mechanism in Material Manufacturing”, “Manufactures of Electronic Chips”, “Crystal Formation”, “Scientific Treatment Problems of Irrigation”, “Soil Erosion and tile drainage” are the present focus of development of channel motion. The formulated physical liquid equations are subsequently calculated by shooting technique with R-K-F (“Runge-Kutta Fehlberg”) scheme. The velocity, temperature as predicted via graphically. we found the velocity dwindle, temperature high production by an escalating statistical value of K (“Couple Stress Parameter”), Ec (“Eckert number”) and Q (“Heat Generation parameter”) respectively. Gradient constraint in addition to improve by an enhancement into Bejan number for various values of “pressure gradient parameter”.

Integrated modeling of cracking during deep penetration laser welding of nickel alloys

During deep penetration laser welding of nickel alloys, interactions between composition and processing conditions can lead to the formation of defects. Inconel 740H, for example, has demonstrated a susceptibility to horizontal fusion zone cracking at locations between 70% and 80% of the weld depth during laser welding at powers above 5 kW. Coupling three-dimensional heat transfer, fluid flow, and stress modeling tools allowed that both the strain rate and stress normal to the solidification direction to be calculated. In the Inconel 740H welds, cracks formed at locations where the strain rate and stress simultaneously reached critical levels. No cracking was observed in the Inconel 690 welds, since the strain rate and stress did not simultaneously reach these critical levels.

An Axially Compressed Moving Nanobeam Based on the Nonlocal Couple Stress Theory and the Thermoelastic DPL Model

This article introduces a new model that can be used to describe elastic thermal vibrations caused by changes in temperature in elastic nanobeams in response to transverse external excitations. Using the idea of nonlocal elasticity and the dual-phase lagging thermoelastic model (DPL), the coupled equations of motion and heat transfer were derived to explain small-scale effects. Additionally, modified couple stress theory (MCST) and Euler–Bernoulli (EB) beam assumptions were considered. The proposed theory was verified by considering the thermodynamic response of nanobeams moving horizontally at a constant speed while one end is subjected to a periodic thermal load. The system of governing equations has been solved numerically with the help of Laplace transforms and one of the tested evolutionary algorithms. The effects of changing the nonlocal modulus, the magnitude of the external force, and the length scale parameter on the system fields were investigated. It is also shown how the behavior of the thermal nanobeam changes depending on the phase delay factors in addition to the horizontal velocity of the beam. To determine this model’s accuracy, its results were compared with the results of the classical continuity model and thermoelastic concepts. The numerical results show that when the nanobeam moves, the length scale can change the studied thermal and mechanical vibration wave patterns and physical fields. Additionally, during thermally stimulated vibrations, thermodynamic effects that have implications for the dynamic design and performance improvement of nanostructures must be considered.

Hydromagnetic Flow of Two Immiscible Couple Stress Fluids through Porous Medium in a Cylindrical Pipe with Slip Effect

In this study, the steady hydromagnetic flow of two immiscible couple stress fluids through a uniform porous medium in a cylindrical pipe with slip effect is investigated analytically. Essentially, the flow system is divided into two regions, region I and region II, which occupy the core and periphery of the system, respectively. The flow is driven by a constant pressure gradient applied in a direction parallel to the cylinder’s axis, and an external uniform magnetic field is applied in the direction perpendicular to the direction of fluid motion. Instead of the classical no-slip condition, the slip velocity along with vanishing couple stress boundary conditions is taken on the surface of the rigid cylinder, and continuity conditions of velocity, vorticity, shear stress, and couple stress are imposed at the fluid-fluid interface. The governing equations are modeled using the fully developed flow conditions. The resulting differential equations governing the flow in the two regions are converted to nondimensional forms using appropriate dimensionless variables. The nondimensional equations are solved analytically, and closed-form expressions for the flow velocity, flow rate, and stresses are derived in terms of the Bessel functions. The impacts of several parameters pertaining to the flow such as the magnetic number, couple stress parameters, Darcy number, viscosity ratio, Reynolds number, and slip parameter on the velocities in respective regions are examined and illustrated through graphs. The flow rate’s numerical values are also calculated for different fluid parameters and displayed in tabular form. It is found that increasing the magnetic number, viscosity ratio, Reynolds number, and slip parameters decreases the velocities of the fluids whereas increasing the couple stress parameter, Darcy number, and pressure gradient increases fluid velocities. The results obtained in this paper show an excellent agreement with the already existing results in the literature as limiting cases.

Analysis of Non-Linear on the House Convection Stream of Couple Stress Micro-Polar Nano-Fluids Past Vertical Cone with Non-Fourier’s Heat and Non-Fick’s Mass Fluxes

The main goal of this study is to analyze the effects of different governing parameters such as buoyancy forces, and thermal relaxation time parameter in non-linear convection flow on the combined two fluids couple stress and micro-polar nano-fluid over a vertical cone with non-isothermal surface with heat and mass transfer with non-Fourier’s heat and non-Fick’s Mass fluxes numerically. The mathematical modeling for the stream difficulty has been made with fitting similarity transformation by non-dimension variable. Major non-linear boundary value difficulties were hooked on combined high regulates non-linear ordinary differential equations. The significance of constraints on velocities, thermal and solutal profiles are evaluated and revealed through the graphs and tables. The convergence test has been maintained; on behalf of spots number larger than apposite web, the meticulousness isn’t influenced. The novelty of the study lies in the analysis on combined two fluids with different constitutive equations over a cone with non-isothermal surface which has little attentions. Findings indicate that enlarging the values of couple stress parameter A permit boost to characteristic measure polarity of fluid that decline velocity profile k′(α), Nusselt, and Sherwood numbers (H′ (0), p′ (0)), but it upsurges angular velocity l (α), skin friction coefficient and wall pair stress.