Couple Stress Research Articles

Couple stress nanofluid flow through a bifurcated artery — Application of catheterization process

Couple stress nanofluid flow through a bifurcated artery — Application of catheterization process

Two-phase flow of couple stress fluid thermally effected slip boundary conditions: Numerical analysis with variable liquids properties

The study of multiphase flows has earned much attention from researchers due to its numerous applications in mechanics and industry such as sewage management, synthetic fabrication, electricity generation, and medication processes. In the present work, we examined the Poiseuille flow of a couple stress fluid between parallel plates in presence of velocity and temperature slip boundary conditions. The effects of thermal conductivity and thermal radiations, variable viscosity, and non-uniform magnetic field on velocity and temperature fields in the existence of hafnium nanoparticles are also investigated. The temperature-dependent viscosity model, namely, Vogel’s model is utilized. The non-linear system of equations is solved numerically by using the shooting technique due to its fast convergence and prosperity to initial approximation. It is examined that the velocity slip parameter speeds up the flow rate of fluid but decelerated the temperature field while the temperature slip parameter upsurges the temperature of the fluid. It is also investigated that the concentration of nanoparticles enhanced both the velocity and temperature of the fluid. Further, the comparison of Newtonian and non-Newtonian (Couple stress fluid) is expressed with the help of graphs. To check the validation of results, a comparison with previous literature is also presented.

Weighted Residual Approach for Bending Analysis of Nanobeam Using by Modified Couple Stress Theory

With the development of nanotechnology, interest in nanomaterials has increased significantly in recent years. This study examines the bending analysis of a nanobeam with modified couple stress theory and weighted residual methods. The formulas derived for calculating bending analysis results in the article has been found by using Weighted Residual Method. The results have compared to show effects on nanobeam and the calculated values are shown in the graphs and tables. The results obtained are compared with the results already found in the literature and it was observed that they are consistent.

A Magnetite–Water-Based Nanofluid Three-Dimensional Thin Film Flow on an Inclined Rotating Surface with Non-Linear Thermal Radiations and Couple Stress Effects

This study is related to the heat energy transfer during 3D nanofluid (water-based) motion over a rotating surface by incorporating the combined impacts of thermal radiations and couple stress. The flow is modeled by a set of non-linear coupled PDEs, which is converted to a set of coupled non-linear ODEs by using suitable similarity transformations. The transformed equations are solved with the built-in NDSolve command. The effects of relevant interesting parameters on the nanofluid velocity components and temperature distribution are explained through various graphs. It is found that the velocity component f(η) is increased with higher values of γ and A0 while it drops with an increasing rotation parameter and nanoparticle volume fraction. The fluid temperature increases with higher αnf, Rd, ϵ2, ϵ3, A1 and drops with increasing Pr, ϵ1 and couple stress parameter (A0). The Nusselt number remains constant at a fixed Pr and Rd, whereas it increases with increasing Pr and is reduced with rising Rd. A comparison between the achieved results is carried out with the analytical results through different tables. An excellent agreement is observed between these results.

A methodological contribution to failure prediction of glass ceramics sealings in high-temperature solid oxide fuel cell stacks

Solid oxide fuel cells (SOFCs) provide electrical energy through a highly efficient direct transformation of chemical energy stored in fuels. The sealing between the stacked components of the SOFC has to prevent gas leakage towards the environment as well as mixing of fuel gas and oxidant in order to ensure a reliable long-term operability. Hence, the understanding of the sealing loading conditions and the failure assessment plays a major role regarding the improvement of current and future SOFC designs. In the present study, glass ceramics sealing failure is investigated by means of a current SOFC design. For this purpose, the stresses in the sealings are firstly examined by employing a fully parameterized three-dimensional finite element model. On the basis of a canonical example, the underlying physical mechanisms, which are responsible for the occurrence of stresses, are identified and their influence is discussed. Since the initiation of sealing failure is complex and depends on several parameters, a methodology for failure assessment is proposed. In this context, the glass transition temperature is of superordinate importance. Since the material properties differ significantly depending on whether the operating temperature is below or above the glass transition temperature, several competing failure mechanisms must be considered. • Full three-dimensional model of an SOFC stack designed by Forschungszentrum Jülich. • Identifying mechanical mechanisms in the context of high temperature sealing failure. • Proposal of a methodology for the assessment of sealing failure in SOFC stacks. • Coupled stress and energy criterion for T < T g . • Viscoelastic considerations for T > T g .

Numerical study on the bearing response trend of perforated sheet-type sand fences

• The displacement and stress of the sand fence had three stages with time. • The stress on the sand fence was mainly distributed at the bottom of the column. • The maximum stress on the sand fence increases with the increase of wind speed. • The stress on the sand fence increases with the decrease of pore sizes. Based on the 3D fluid–solid coupling numerical calculation method, a systematic study was conducted on the bearing characteristics of a perforated sheet-type sand fence at a given penetration rate, opening size, and wind velocity. According to the results of this study, both the displacement and stress of the sand fence experienced an impact stage, a coupling stage, and a stabilization stage under different wind velocities and times. At the initial moment of the impact stage, both the displacement and stress of the sand fence reached their maximum, i.e., the maximum position of the sand fence displacement was at the top of the panel central line, whereas the maximum position of the stress was at the site of the column 4.5 cm away from the column bottom. The duration of the impact stage was 1.5 s and did not change with the opening size or wind velocity. In the coupling stage, the displacement and stress of the sand fence underwent intense fluctuations, and the amplitude of fluctuations decreased with time. The duration of the coupling stage did not change with opening size, but increased with the increase in wind velocity. In the stabilization stage, both the displacement and stress of the sand fence reached a stable state and did not significantly change with time. In each stage, both the displacement and stress of the sand fence are inversely proportional to the opening size and directly proportional to the wind velocity, i.e., the lower the opening size, the higher the wind velocity, and the greater the displacement and stress of the sand fence. However, when the hole diameter drops below 1.03 cm, it is no longer a main influencing factor of sand fence displacement or stress change. For the sand fence in each stage, the panel displacement was higher than the column displacement, whereas the column stress was higher than the panel stress. This paper provides a basis for the design and optimization of sand fence structures, lays the foundation for establishing a mechanics-physics model for the stress distribution of sand fence structures, and presents relatively high research values.

Nonlinear vibration of fractional viscoelastic micro-beams

Nonlinear vibration of a fractional viscoelastic micro-beam is investigated in this paper. The Euler–Bernoulli beam theory and the nonlinear von Kármán strain are used to model the beam. The small-scale effects are considered by employing the Modified Couple Stress Theory (MCST). The viscoelastic material of the beam is modeled via the fractional Kelvin–Voigt model. Utilizing the Hamilton’s Principle, a partial fractional differential equation is derived as the governing equation of motion. The Finite Difference Method (FDM) and the Galerkin method are used together for solving the partial fractional differential equation. The FDM is utilized to discretize the time domain, and the Galerkin method is employed to discretize the space domain. In this paper, the FDM and the Shooting method are coupled together to find the periodic solution of the fractional micro-beam and draw the corresponding amplitude–frequency curve. The effects of the order of the fractional derivative, viscoelastic model, and the micro-scale are studied numerically here in this study. Numerical simulations suggest that, the effect of the fractional derivative is very strong and must be considered for modeling the viscoelastic behavior; especially when the amplitude is high. Results also show that the effects of the nonlinear viscoelastic part are considerable when the amplitude is high; this may happen when the excitation frequency is near the natural frequency, at which the maximum amplitude occurs.

Analysis of Love Waves in Pre-Stressed Layer Sandwiched between Dry Sandy Layer and Couple Stress Substrate

Analysis of Love Waves in Pre-Stressed Layer Sandwiched between Dry Sandy Layer and Couple Stress Substrate

Study of Heat and Mass Transfer to Magnetohydrodynamic (MHD) Pulsatile Couple Stress Fluid Between Two Parallel Porous Plates

Study of Heat and Mass Transfer to Magnetohydrodynamic (MHD) Pulsatile Couple Stress Fluid Between Two Parallel Porous Plates

Nonlinear Static Analysis of a Bi-directional Functionally Graded Microbeam Based on a Nonlinear Elastic Foundation Using Modified Couple Stress Theory

Nonlinear Static Analysis of a Bi-directional Functionally Graded Microbeam Based on a Nonlinear Elastic Foundation Using Modified Couple Stress Theory

Inflow Performance Analysis of a Horizontal Well Coupling Stress Sensitivity and Reservoir Pressure Change in a Fractured-Porous Reservoir

Abstract Stress sensitivity has always been a research hotspot in fractured-porous reservoirs and shows huge impacts on well productivity during the depletion development. Due to the continuous reservoir pressure change, accurate evaluation of stress sensitivity and its influence on well productivity is of great significance to optimize well working system. Taking horizontal well trajectory as the research object, the principal focus of this work is on the analysis of inflow performance for a horizontal well coupling stress sensitivity and reservoir pressure change in a fractured-porous reservoir. Firstly, a relationship between permeability damage rate and stress sensitivity coefficient was established to quantitatively evaluate the influence of reservoir pressure and stress sensitivity on reservoir permeability. Secondly, considering stress sensitivity and reservoir pressure drop, a set of practical productivity equations were derived for a horizontal well in a fractured-porous reservoir by adopting the equivalent seepage resistance method. Finally, the influence of relevant important factors on the inflow performance of horizontal wells was discussed in depth. Results show that a positive correlation exists between stress sensitivity coefficient and maximum permeability damage rate. At the same maximum permeability damage rate, high initial reservoir pressure corresponds to low stress sensitivity coefficient. In general, stress sensitivity coefficient mainly ranges from 0 to 0.2. Reservoir pressure change drastically affects the production dynamic characteristics of horizontal wells, and both the inflow performance curve and the production index curve decline and shrink as reservoir pressure decreases. Stress sensitivity is negatively correlated with horizontal well productivity, and the inflow performance/production index curve bends closer to bottom-hole pressure axis, and an inflection point can be observed with the aggravation of stress sensitivity. In addition, horizontal wellbore length and initial reservoir permeability also show significant effects on the inflow performance and are positively correlated with well productivity. For water cut, it has little effect on the well production when bottom-hole pressure drawdown is low, but its effect gets stronger as the drawdown becomes higher. Meaningfully, depending on these newly established productivity equations, a reasonable production system can be quantitatively optimized and achieved for the horizontal wells in fractured-porous reservoirs.

Theoretical study of an unsteady ciliary hemodynamic fluid flow subject to the Newton’s boundary conditions

This article addresses the hemodynamic flow of biological fluid through a symmetric channel. Methachronal waves induced by the ciliary motion of motile structures are the main source of Couple stress nanofluid flow. Darcy’s law is incorporated in Navier-Stokes equations to highlight the influence of the porous medium. Thermal transport by the microscopic collision of particles is governed by Fourier’s law while a separate expression is obtained for net diffusion of nanoparticles by using Fick’s law. A closed-form solution is achieved of nonlinear differential equations subject to Newton’s boundary conditions. Moreover, the current findings are compared with previous outcomes for the limiting case and found a complete coherence. Parametric study reveals that nanoflow is resisted by employing Newton’s boundary conditions. Thermal profile enhancement is contributed by the viscous dissipation parameter. Finally, one infers that hemodynamic flow of non-Newtonian fluid is an effective mode of heat and mass transfer especially, in medical sciences for the rapid transport of medicines in drug therapy.

Evolution and control of deformation mechanisms in micro-grooving of Zr-based metallic glass

The evolution of deformation mechanisms with increasing depth of cut (DOC) in micro-grooving of Zr-based metallic glass was deeply investigated in this study for the first time. The micro-grooving characteristics of metallic glass were initially studied by nanoscratch test, which verified that the material removal mode abruptly changes from extrusion mode to cutting mode with increase of DOC. Based on the free-volume theory, a dynamic model coupling stress, temperature and free volume concentration was used to simulate the change of deformation characteristics with DOC. The results showed that the deformation mechanism of metallic glass is closely related to free volume flow, which is significantly affected by average strain rate and free volume flow coefficient in deformation zone and can be tuned with different DOC. Considering that free volume flow is determined by its flow coefficient and concentration, we proposed to control the deformation characteristics of metallic glass in micro-grooving by heat treatment and verified its effectiveness experimentally. • Materials removal mode of metallic glass changes with the increase of depth of cut. • The evolution of deformation mechanisms was studied using a dynamic model. • Free volume flow affects the evolution of deformation mechanisms significantly. • Deformation characteristics of metallic glass were experimentally modulated.

Exact Solutions to the Navier–Stokes Equations with Couple Stresses

This article discusses the possibility of using the Lin–Sidorov–Aristov class of exact solutions and its modifications to describe the flows of a fluid with microstructure (with couple stresses). The presence of couple shear stresses is a consequence of taking into account the rotational degrees of freedom for an elementary volume of a micropolar liquid. Thus, the Cauchy stress tensor is not symmetric. The article presents exact solutions for describing unidirectional (layered), shear and three-dimensional flows of a micropolar viscous incompressible fluid. New statements of boundary value problems are formulated to describe generalized classical Couette, Stokes and Poiseuille flows. These flows are created by non-uniform shear stresses and velocities. A study of isobaric shear flows of a micropolar viscous incompressible fluid is presented. Isobaric shear flows are described by an overdetermined system of nonlinear partial differential equations (system of Navier–Stokes equations and incompressibility equation). A condition for the solvability of the overdetermined system of equations is provided. A class of nontrivial solutions of an overdetermined system of partial differential equations for describing isobaric fluid flows is constructed. The exact solutions announced in this article are described by polynomials with respect to two coordinates. The coefficients of the polynomials depend on the third coordinate and time.

Response of Non-Local and Phase-Lags due to Ramp-Type Loading in Modified Couple Stress Thermoelastic with Mass Diffusion

Response of Non-Local and Phase-Lags due to Ramp-Type Loading in Modified Couple Stress Thermoelastic with Mass Diffusion

Bioconvection Due to Gyrotactic Microorganisms in Couple Stress Hybrid Nanofluid Laminar Mixed Convection Incompressible Flow with Magnetic Nanoparticles and Chemical Reaction as Carrier for Targeted Drug Delivery through Porous Stretching Sheet.

In this paper, the steady electrically conducting hybrid nanofluid (CuO-Cu/blood) laminar-mixed convection incompressible flow at the stagnation-point with viscous and gyrotactic microorganisms is considered. Additionally, hybrid nanofluid flow over a horizontal porous stretching sheet along with an induced magnetic field and external magnetic field effects that can be used in biomedical fields, such as in drug delivery and the flow dynamics of the microcirculatory system. This investigation can also deliver a perfect view about the mass and heat transfer behavior of blood flow in a circulatory system and various hyperthermia treatments such as the treatment of cancer. The simple partial differential equations (PDEs) are converted into a series of dimensional ordinary differential equations (ODEs), which are determined using appropriate similarities variables (HAM). The influence of the suction or injection parameter, mixed convection, Prandtl number, buoyancy ratio parameter, permeability parameter, magnetic parameter, reciprocal magnetic prandtl number, bioconvection Rayleigh number, coupled stress parameter, thermophoretic parameter, Schmidt number, inertial parameter, heat source parameter, and Brownian motion parameter on the concentration, motile microorganisms, velocity, and temperature is outlined, and we study the physical importance of the present problem graphically.

Pulsating flow of electrically conducting couple stress nanofluid in a channel with ohmic dissipation and thermal radiation – Dynamics of blood

The present work discloses the magnetohydrodynamic pulsating flow of blood-carrying [Formula: see text] nanoparticles in a channel with the viscous dissipation and Joule heating effects. Couple stress fluid is treated as blood which is the base fluid. The Maxwell Garnett model for thermal conductivity of nanofluid is considered. The thermal radiation and heat source/sink impacts are taken into account. Analytical expressions for dimensionless flow variables are obtained by employing the perturbation method. The impact of active parameters on flow variables is graphically presented. The obtained results show that the velocity of nanofluid increases with an increment in frequency parameter, whereas it decreases for a rise in Hartmann number, nanoparticles volume fraction and couple stress parameter. There is an enhancement in temperature of nanofluid with increasing viscous dissipation, whereas there is a decrease in temperature with an increase in the applied magnetic field. The Nusselt number rises with an enhancement in volume fraction of nanoparticles and Hartmann number at both the walls. Further, the validity of present results is assured by the comparison of analytical and numerical outcomes with an excellent harmony.

Entropy minimization on magnetized Boussinesq couple stress fluid with non-uniform heat generation

This article aims to investigate the generation of entropy for the magnetized coupled stress fluid passed through a permeable stretching cylinder that creates the condition of convective heat transfer. Additionally, in the uneven heat source in the flow field, we also analyzed our research. The properties of heat transfer taking into account in the perspective of thermal radiation. The main nonlinear partial differential equations (NPDE) become ordinary nonlinear differential equations by adopting the corresponding dimensionless variables. The recognized repeated shooting technique combined with the fourth-order standard Runge-Kutta integration solution to evaluate the resulting nonlinear ODE numerically. The velocity, temperature profile, streamline, number of local entropy generations, Bejan number, local friction coefficient, and Nusselt number effects of the new flow parameters are explained by graphs and tables. The flow system’s physical properties and the correlation between the parameters were clarified by using statistical methods. The results show that the Bejan number is reduced due to the magnetic source. Generation of entropy promotes the growth of the magnetic field and the Brinkman number, but the coupling stress aspect shows a double effect. The coupled stress parameter reduces the number of Nusselt by a fraction of 4.46%, while in the attendance of a magnetic field, the radiant heat transfer rate increases at a rate of 2.65%. In the attendance of a magnetic field, skin friction reduces the coupling stress factor by a rate of 24.67%. Besides, the current outcomes have been verified by previously published studies and are very acceptable. For the stretched cylinder, which has a curvature parameter of γ = 1.0, and for the flat, stretched surface, γ = 0.0, the thickness of the momentum and the thermal boundary layer are greater.

Convective Flow of Hydromagnetic Couple Stress Fluid with Varying Heating through Vertical Channel

This article addresses the impact of magnetic field induction on the buoyancy-induced oscillatory flow of couple stress fluid with varying heating. Modelled equations for the incompressible fluid are coupled and nonlinear due to the inclusion of viscous heating and thermal effect on the fluid density. Approximate solutions are constructed and coded on a symbolic package to ease the computational complexity. Graphical representations of the symbolic solutions are presented with detailed explanations. Results of the present computation show that the effect of induced magnetic field on the oscillatory flow and heat transfer is significant and cannot be neglected.

Size effects on the band gap of flexural wave propagation in one-dimensional periodic micro-beams

The mechanical properties of micro-scale materials are different from their macroscopic counterparts. This study investigates the impact of the size effect on the band structure of a one-dimensional periodic microstructure. The equation of motion for the Euler–Bernoulli beam model considering the size effect is derived based on the modified coupled stress theory, and the transfer matrix method is employed to obtain the band structure considering the size effect. The results obtained with the modified couple stress theory are compared with those obtained using the classical theory. The size effect increases the flexural stiffness of the micro-beams, causing the band gap to move to a higher frequency. In addition, the effects of the material distribution and geometric period on the band gap are also investigated. It is found that the size effect, which has a significant effect on the band structure of the microstructure, cannot be neglected.