Lower Wall Of Channel Research Articles

Entropy Generation in Third-Grade Non-Newtonian Fluid Flow and Heat Transport Through Porous Medium in a Horizontal Channel under Heat Generation

In this study, entropy production in flow along with heat transport of non-Newtonian fluid via porous medium, is analyzed. For fluid flow via porous medium, a modified Darcy resistance term, is taken in the momentum equation for third-grade fluid. Temperature-dependent viscosity is considered using Vogel’s model viscosity. Using adequate transformations, the momentum and heat transport equation are reduced to non-dimensional form and solved analytically invoking homotopy analysis method on MATHEMATICA software. Effects of parameters arising in the study are depicted by graphs on velocity distribution, temperature distribution, and entropy production with Bejan number and discussed. For validity of current findings, the values of velocity and temperature are computed for particular values of the parameters and equated with previously published results, excellent agreement achieved. Furthermore, skin-friction coefficient and Nusselt number values are expressed in tabular form for various values of relevant parameters and discussed. It is noticed that slip parameters $\left( \gamma \right)$ and $\left( \beta \right)$ reduce the entropy generation number $\left( NS \right)$. Also noticed that skin friction coefficient upsurges with rising velocity slip parameter $\left( \gamma \right)$ value while, effect of temperature slip parameter $\left( \beta \right)$ is observed to lessen Nusselt number in the absolute sense. HIGHLIGHTS Entropy production in third grade non-Newtonian fluid flow and heat transfer in a channel via porous medium is investigated in the presence of a heat source. Slip boundary conditions are applied. The resulting governing equations are solved analytically using the homotopy analysis method (HAM). Maximum entropy production observed near the lower wall of channel and Bejan number attains maximum value in middle of the channel. GRAPHICAL ABSTRACT

Numerical and neural network approaches to heat transfer flow in MHD dissipative ternary fluid through Darcy-Forchheimer permeable channel

The study of heat transfer in fluid flows across permeable media is critical in many engineering applications, including energy systems, cooling technologies, and chemical processes. This study aims to explore the impact of joule heating and heat transfer flow of an MHD dissipative ternary fluid through a channel embedded in a Darcy-Forchheimer permeable medium. Additionally, the utilization of ternary hybrid nanofluids, composed of a base fluid and three nanoparticles Al2O3, MoS2, and Cu has emerged as a promising avenue for augmenting thermal conductivity and heat transfer rates. The governing equations are transformed into a set of coupled ordinary differential equations by employing similarity variables and simplified by bvp4c and artificial neural network (ANN) model approaches. Results reveal that significant enhancement in the velocity field at the lower channel wall and reductions at the upper wall, while fluid temperature decreases with increasing Prandtl number. Further, the heat transfer rate increases with an increase in the Prandtl number and magnetic field whereas the skin friction decays with an increase in the magnetic field. Meanwhile, the comparison was carried out for the temperature field by using bvp4c & ANN and the results are strongly correlated.

On the interaction between a detonation wave and an inert gas plug: A numerical investigation

Employing inert gases to attenuate and obstruct the propagation of detonation waves has proven to be an effective strategy for mitigating potential damage in the realm of industrial safety, which involves complex physical and chemical mechanisms. This study utilizes an in-house solver built on the OpenFOAM platform to examine the interaction between a detonation wave and an inert gas plug of various lengths. The results reveal that as the length of the inert gas plug increases, various detonation states emerge downstream of the gas plug, and an exponential relationship is observed between the detonation re-initiation distance and the gas plug's length. In the process of detonation re-initiation, the non-isentropic process within the viscous boundary layer plays a crucial role in initiating the flames at the upper and lower channel walls. Later, the collision between flames initiates the detonation wave. Additionally, a localized detonation can also be triggered through the interaction between the compression wave and the wall. Notably, the impingements of the detonation wave and the transmitted shock wave induce the mixing and downstream motion of the gas plug. In the presence of the detonation re-initiation, the motion patterns of the left and right interfaces of the gas plug can be categorized into two distinct stages, which are mainly because of the impingement of backpropagation expansion waves and the hindrance of the high pressure generated by the detonation re-initiation, respectively. Also, as the length of the inert gas plug increases, the velocity difference between the two stages gradually decreases.

The classical unsteady boundary layer: A numerical study

AbstractThe transition process from a laminar to turbulent flow near a solid wall (e.g., at the suction side of a slender airfoil) is still not fully understood. We focus on the early stage of the flow transition based on boundary layer (BL) theory, that is, high Reynolds number asymptotic expansions, which reduce the Navier–Stokes equations into simplified forms. While steady solutions of the resulting classical BL equations and corresponding regularisations based on viscous–inviscid interaction theory are studied quite extensively, there is only few information about the fully time‐dependent scenario. Hence, we numerically study the classical unsteady BL and its breakdown structure, the Van Dommelen–Shen singularity, on the simplest example we can imagine, the incompressible planar fluid flow through a rectangular channel with suction. The depicted BL builds at the lower channel wall and follows initially a generic Blasius behaviour, which gets temporally modulated through suction by means of a slot located at the upper wall. As usual, the main part of the flow is inviscid and governed by Laplace's equation. Remarkably, the wall‐slip velocity, or alternatively the pressure gradient imposed on the BL, can be calculated in closed form and we have full control of its temporal dependency through the variation of the applied suction strength. This specific flow configuration allows us to split off the initial Blasius solution and promises high‐accuracy solutions of the remaining unsteady BL equation in the scaled stream function formulation. The Chebyshev collocation is used in the wall‐normal direction, where the infinite domain is mapped onto [ − 1, 1]. On the contrary, we discretise the mainstream direction with a finite difference scheme of second‐order accuracy, which proved to be more precise near the build‐up of singularities. In order to trigger a dynamic breakdown of the unsteady BL equations, we increase the suction rate continuously from zero to a level slightly above the critical value (obtained from the steady case). As a consequence, the system cannot relax to a steady solution and instead blows up in finite time at some mainstream position. We try to resolve this process with high resolution and the final goal is to verify the inner structure (the two‐dimensional blow‐up profile) of the Van Dommelen–Shen singularity and its role in flow separation and transition.

Numerical Calculation of Heat Transfer in a Rectangular Channel with Triangular Vortex Generators in the Channel at Blade Angle 30° for Reynolds no. of 800, 1200

Abstract: The vortex generators in this study are placed at angle of 30° in a rectangular channel. These vortices create the down wash flow towards the lower channel wall while the up wash flow is away from the wall which is found in the outside region of the vortices. Along the downstream direction, the secondary velocity vectors decreases while the distance between the vortex cores increases. Thinning of the thermal boundary layer thus occurs in between the two vortices. The variation of span wise averaged Nusselt number was calculated at different values of x at Reynolds number of 800, 1200. We considered parametric studies between channel without winglet and with winglet pair. It shows that the span wise averaged Nusselt number increase with the increment of Reynolds no. at particular x. it is observed the behaviour at these Reynolds no with blade angle 30°. The increment in the span wise averaged Nusselt no. can be observed from these numerical calculations. the effect of vortex generators in the spanwise averreged nusselt number. The comparison between the plots of spanwise avereged Nusselt number with and without vortex generators shows that there is a considerable increase in Nusselt number near the vortex generator region and this effect decreases as we move far from the vortex generator region in the stream wise direction.

Influence of streamwise and spanwise wall magnet arrays on near-wall MHD turbulence

ABSTRACT The effect of a permanent, localised and non-uniform magnetic field on the near-wall turbulence in a fully developed channel flow is analysed through direct numerical simulations. The magnetic field distribution is obtained by an arrangement of magnets placed on the upper and lower channel walls, producing preferentially either a streamwise (i.e. in the main flow direction) or a spanwise magnetic field component. The wall shear stress is drastically reduced under the effect of the streamwise arrangement of the wall magnets wherein both streamwise and wall-normal magnetic fields are involved. The magnetic braking effect leads to an important increase of the body force. Paradoxically enough, the small-scale turbulent activity is significantly increased above the low buffer layer in this case. On the opposite, imposing a magnetic field with a predominant spanwise component reduces tremendously the population of the turbulent shear stress producing eddies by directly affecting the regeneration of the buffer layer quasi-streamwise vortices. The flow is quasi-relaminarised between the magnets in the low-buffer and viscous sublayers. The wall shear increases in a predictable and deterministic way over the magnets, wherein the wall normal magnetic field component induces electric current loops.

Study of peristaltic activity in non-linear blood analysis of Williamson fluid in a microchannel

The present investigation is modeled to study the effect of homogeneous and heterogeneous reactions on the peristaltic blood transportation of electrically conducting Williamson fluid in an asymmetric microchannel under velocity slip conditions. The mechanism of heat transfer is also examined in conjunction with viscous dissipation and thermal radiation. Implementation of small Reynolds number and large wavelength concepts leads to a reduction in the complexity of the system. Series solutions for velocity, temperature, stream function, and concentration fields are found using the regular perturbation technique. Using Mathematica software, Simpson’s rule was used to evaluate the pumping features such as pressure rise and frictional force. The effects of embedded parameters are portrayed and discussed by using a graphical approach. The skin friction and Nusselt number at the channel walls are established for a choice of assessments of significant parameters and which are exhibited in a tabular manner. It is observed that an enhancement in the values of Weissenberg number fluid velocity reduces at the lower channel wall whereas it increases at the channel upper wall.

Unsteady convective ferrohydrodynamic flow of MnZnFe2O4/FeCrNbB - EG hybrid nanofluid in a horizontal channel with porous fins and semi-circular heaters

In this study, we investigate the unsteady incompressible flow of ethylene-glycol (EG) based MnZnFe2O4/ FeCrNbB hybrid nanofluid through a horizontal channel. Three semi-circular heaters are mounted on the lower channel wall, whereas four porous fins are mounted on the upper channel wall. The Forchheimer model is utilized to describe convective nanofluid flow within the porous fins. Also, a variable magnetic field is produced by an electrical wire within each heater and induces motion and heat transfer within the hybrid nanofluid. Governing equations associated with the mathematical model are numerically solved via the mixed finite element technique. Using the computed graphical and tabular results, we examine the effects of the magnetic parameter (105≤Mn≤3×106), size of the porous fins (0.2≤hfin≤0.6), heater radius (0.2≤r0≤0.3), and solid volume fractions of MnZnFe2O4 and FeCrNbB nanoparticles (0≤ϕ1≤0.02 and 0≤ϕ2≤0.02) on the flow velocity, streamlines, isotherms, pressure drop, and heat transfer performance in the channel. The main findings of the study are that increasing the magnetic number and volume fractions of MnZnFe2O4 and FeCrNbB nanoparticles, and decreasing the height of the porous fins and size of the heaters, leads to greater convective heat transfer in the channel. Furthermore, the pressure drop is enhanced when each of the aforementioned parameters is increased.

Nano-ferrofluid (Mn–Zn, CoFe2O4, Fe3O4) flow in a permeable channel with induced magnetic field

This article deals with the magnetohydrodynamics (MHD) transportation of water-based nano-ferrofluid in a channel. Three different types of ferrofluid suspensions, to be specific, water-containing magnetite, cobalt ferrite, and manganese-zinc ferro particles (, , ) are taken to observe flow field, induced magnetic field, and temperature field. The non-dimensional mathematical model is solved numerically under the specified wall and free stream conditions. The key parameters emerging in the present model are Prandtl number, porosity, the reciprocal of magnetic Prandtl number and magnetic parameter. The impact of these parameters on the flow field, velocity, temperature, and gradient of magnetic stream function for various ferrofluid suspensions is discussed graphically. Altogether, a more prominent velocity of fluid is noticed for magnetite ferro particles as contrasted with cobalt or manganese-zinc ferro particles due to the lower density of magnetite ferro particles. It is observed that when the volume fraction of nanoparticle rises from 0.1 to 0.6, heat transfer at the lower wall of channel is increased by 11 and decreased by 36 at the upper wall of the channel.

Heat transfer enhancement by a pair of asymmetric flexible vortex generators and thermal performance prediction using machine learning algorithms

• Heat transfer enhancement system including two flexible vortex generators is analyzed by using an immersed boundary method. • Effects of the inclination angle, bending rigidity, and the gap distance on the thermal performance are analyzed in detail. • The thermal performance of the present heat transfer system is enhanced up to 122% as compared to baseline flow without flexible vortex generators. Heat transfer should be considered in the design process of various industrial fields such as electric-electronics, plants and refrigeration and air conditioning, etc. Many researchers have introduced vortex generators to promote mixing of fluids, thereby improving heat transfer performance. Convective heat transfer can be enhanced by using vortex generators where, however, the disadvantage of increased mechanical loss due to increased pressure drop is not avoidable. In order to compensate for the penalty, the present study utilizes the characteristics of self-sustained flapping motions of the flexible vortex generator to improve heat transfer without much increasing the pressure drop. The two flexible vortex generators (FVGs) fixed on the upper and lower channel walls, respectively, are introduced in the present study and they take the form of asymmetric configurations by adjusting the inclination angles. The heat transfer performance is observed to depend on the parametric conditions of FVGs such as the inclination angle, bending rigidity, and the gap distance between them. The present system including the asymmetric FVGs shows the improvement of thermal performance by 122% as compared to the baseline flow when the bending rigidity is 0.06, the initial inclination angle is 75°, and the gap distance is 2.4 times the length of FVGs. The attracting Lagrangian coherent structures (LCS) are visualized by calculating the finite-time Lyapunov exponent (FTLE) field to analyze the effects of the vortex structures near the heated channel walls on the fluid mixing. The net energy loss and average heat transfer are predicted by the three machine learning algorithms, i.e ., artificial neural network (ANN), support vector regression (SVR), and random forest (RF), where the inclination angle, bending rigidity, and gap distance of FVGs are selected as input data. The SVR and ANN algorithms show the best performance in predicting the mean energy loss and the heat transfer, respectively, with the R 2 value of above 0.99 and 0.95.

Reducing Transient Energy Growth in a Channel Flow Using Static Output Feedback Control

Transient energy growth of flow perturbations is an important mechanism for laminar-to-turbulent transition that can be mitigated with feedback control. Linear quadratic optimal control strategies have shown some success in reducing transient energy growth and suppressing transition, but acceptable worst-case performance can be difficult to achieve using sensor-based output feedback control. In this study, we investigate static output feedback controllers for reducing transient energy growth of flow perturbations within linear and nonlinear simulations of a subcritical channel flow. A static output feedback linear quadratic regulator (SOF-LQR) is designed to reduce the worst-case transient energy growth due to flow perturbations. The controller directly uses wall-based measurements to optimally regulate the flow with wall-normal blowing and suction from the upper and lower channel walls. We show that SOF-LQR controllers can reduce the worst-case transient energy growth of flow perturbations. Our results also indicate that SOF-LQR controllers exhibit robustness to Reynolds number variations. Further, direct numerical simulations show that the designed SOF-LQR controllers increase laminar-to-turbulent transition thresholds under streamwise disturbances and delay transition under spanwise disturbances. The results of this study highlight the advantages of SOF-LQR controllers and create opportunities for realizing improved transition control strategies in the future.

Effect of NP shapes on Fe3O4 – Ag/kerosene and Fe3O4 – Ag/water hybrid nanofluid flow in suction/injection process with nonlinear-thermal-radiation and slip condition; Hamilton and Crosser's model

This study examines the flow and thermal properties of water and kerosene hybrid nanofluids in a horizontal microchannel. The effects of nonlinear thermal radiation, heat source coefficient, convective and slip boundary conditions on nanofluids in a microchannel have been studied. The impact of different nanoparticle shape factors on the temperature of nanofluids has also been analysed. The governing partial differential equations have been transformed in to ordinary differential equations using dimensionless terms. In the next step, the corresponding ordinary differential equations have been cracked using the RKF45 numerical approach, and the particles shape factor on dimensionless velocity and energy fields for hybrid nanofluid then reported. The results revealed that the spherical and lamina shape factors for both water and kerosene hybrid nanofluid differ the most, the water-based hybrid nanofluid has a higher velocity than the kerosene-based hybrid nanofluid, the thermal energy of both water and kerosene-based hybrid nanofluid was higher in the lower channel plate than the upper channel plate, flow rate falls near the lower channel wall and increases towards the upper channel wall as Reynolds number increases. Thermal energy and entropy generation decrease as the temperature parameter rises.

Forced Convection of Non-Newtonian Nanofluid Flow over a Backward Facing Step with Simultaneous Effects of Using Double Rotating Cylinders and Inclined Magnetic Field

The forced convection of non-Newtonian nanofluid for a backward-facing flow system was analyzed under the combined use of magnetic field and double rotating cylinders by using finite element method. The power law nanofluid type was used with different solid volume fractions of alumina at 20 nm in diameter. The effects of the Re number (100≤Re≤300), rotational Re number (−2500≤Rew≤3000), Ha number (0≤Ha≤50), and magnetic field inclination (0≤γ≤90) on the convective heat transfer and flow features were numerically assessed. The non-Newtonian fluid power law index was taken between 0.8 and 1.2 while particle volume fractions up to 4% were considered. The presence of the rotating double cylinders made the flow field complicated where multiple recirculation regions were established near the step region. The impacts of the first (closer to the step) and second cylinders on the heat transfer behavior were different depending upon the direction of rotation. As the first cylinder rotated in the clockwise direction, the enhancement in the average heat transfer of 20% was achieved while it deteriorated by approximately 2% for counter-clockwise directional rotation. However, for the second cylinder, both the rotational direction resulted in heat transfer augmentation while the amounts were 14% and 18% at the highest speeds. Large vortices on the upper and lower channel walls behind the step were suppressed with magnetic field effects. The average Nu number generally increased with the higher strengths of the magnetic field and inclination. Up to 30% increment with strength was obtained while this amount was 44% with vertical orientation. Significant impacts of power law fluid index on the local and average Nu number were seen for an index of n = 1.2 as compared to the fluid with n = 0.8 and n = 1 while an average Nu number of 2.75 times was obtained for the flow system for fluid with n = 1.2 as compared to case for fluid with the n value of 0.8. Further improvements in the local and average heat transfer were achieved with using nanoparticles while at the highest particle amount, the enhancements of the average Nu number were 34%, 36% and 36.6% for the fluid with n values of 0.8, 1 and 1.2, respectively.

Fundamental motion characteristics and manipulation of ferromagnetic fluid droplet in a channel flow under external magnetic field

Ferromagnetic fluid can be used to as a carrier to transport other materials since its motion can be manipulated by external magnetic field and it is of great importance to reveal the motion regularity of ferromagnetic fluid droplets when they are used as carriers under the action of a magnetic field. In this work, numerical simulations and experimental visualizations were carried out to investigate the transportation process of a ferromagnetic fluid droplet and the controllable behavior of ferromagnetic fluid droplets under the action of a magnetic field. Based on the two-phase lattice Boltzmann method, the motion of ferromagnetic fluid droplets under magnetic field was simulated, and the shape evolution process of the droplets was revealed. Simulation results indicate that the changes of the droplet velocity and the mean outlet velocity of channel fluid all present fluctuation regularities due to the instability of droplet. It was also found that the transportation efficiency is weakened once the droplet contacts with the channel wall. For the ferromagnetic fluid droplet immersed in channel fluid, an external force generated by gradient magnetic field can be used to resist the gravity, and then, it will not sink to the lower channel wall, as revealed by the experiments, the droplet can move along the channel center.

Thermal influence of homogeneously heated Y- shaped flipper on flowing stream in an unwavering rectangular domain

The current study offers the numerical findings on uniformly heated Y-shaped fin embedded in a rectangular domain having height 0.6 m and 2 m length. The no-slip condition is carried at left, upper and lower wall of channel. These walls are taken cold as well. Both the Neumann and adiabatic conditions are implemented at the right wall. The cold Newtonian fluid enters with the parabolic velocity profile from inlet of channel. The problem is controlled mathematically in terms of partial differential equations. The finite element method is adopted along with hybrid meshing scheme to report acceptable solution. The velocity, pressure and temperature distributions around the heated Y-shaped fin are offered graphically. The temperature findings are reported for the cold, adiabatic and heated tips of Y-shaped fin. The line integration around Y-shaped fin is performed to evaluate the lift and drag coefficients values. The lift coefficient and drag coefficient corresponds the lift force and drag force experienced by the heated Y-shaped fin. It is observed that for the higher values of Reynolds number the lift coefficient shows an inciting values while the drag coefficient shows decline nature.

Simulation of thermal radiation in a micropolar fluid flow through a porous medium between channel walls

Among numerous methods which have been employed to reinforce the thermal efficiency in many systems, one is the thermal radiation which is a mode of heat transfer. Another way to improve the thermal efficiency is the utilization of the porous media. The present work includes the study of micropolar flow with allowance for thermal radiation through a resistive porous medium between channel walls. The governing coupled partial differential equations representing the flow model are transmuted into ordinary ones by using the suitable dimensionless coordinates, and then, quasi-linearization is employed to solve the set of relevant coupled ODEs. Effects of physical parameters on the flow under different conditions, arose by varying the governing parameters, are scrutinized and discussed through tables and graphs. A comparison is associated with previously accomplished results and examined to be in an exceptional agreement. The culminations evidently disclose that the porosity parameter and the Reynolds number suppress the microrotation and velocity, while material parameters produce opposite effects. The thermal radiation phenomenon downturns the temperature curves and enhances the heat transfer rate on the lower wall of channel.

Impact of heated triangular ribs on hydrodynamic forces in a rectangular domain with heated elliptic cylinder: Finite element analysis

Abstract The heat transfer in flowing liquid stream towards confined geometries having natural or man-made obstacles offers complex mathematical constraints at the heated body-liquid stream interface. Therefore, to appraise the heat transfer in liquid stream with installed obstacles particularly in terms of hydrodynamic forces remains a topic of great interest for the researchers. Owing such interest, the present article contains the extended evaluation of hydrodynamic forces in a flowing liquid stream with heat transfer individualities. To be more, the Newtonian liquid stream is initiated with the parabolic velocity profile at an inlet of partially heated rectangular channel. The heated elliptic shaped cylinder is placed fixed in between channel as an obstacle. The heated triangular ribs are installed case-wise namely (i) channel without ribs (ii) heated triangular rib at lower wall (iii) heated triangular rib at upper wall (iv) heated triangular rib at both upper and lower walls. The presence of heated triangular ribs as an obstacles modifies the endpoint conditions and hence the developed flow narrating differential system cannot be solved exactly. Therefore, the most trustful numerical method named finite element method with LBB-stable finite element pair is utilized to report acceptable solution in terms of streamlines and isotherms contour plots. The hydrodynamic forces are evaluated for each case by adopting line integration around outer surface of heated elliptic obstacle. It is noticed that when the heated triangular rib is installed on both upper and lower channel walls, the drag coefficient is found considerably high.

A New Model and Analysis for Peristalsis of Carreau–Yasuda (CY) Nanofluid Subject to Wall Properties

Peristaltic movement of non-Newtonian nanofluid obeying Carreau–Yasuda (CY) model across a complaint wall channel is formulated through a different approach. Unlike past researches, we consider the well-known Buongiorno’s model without relying on conventional assumption of constant diffusion coefficients. However, the considered model assumes long wavelength of channel walls compared with the channel width. Lower channel wall is heated by providing convection from hot fluid at temperature Tf. The developed system is coupled and nonlinear which seems difficult to be solved exactly. Hence, numerical computations are made by adopting shooting method-based package NDSolve of MATHEMATICA. A considerable effect of wall slip and rheology on the solution profiles is apparent from the computational results. Moreover, the computed results are aimed at predicting the role of Brownian diffusion and thermophoresis in peristalsis especially when wall elastic effects are present.

Mathematical Model of Oscillations of a Three-Layered Channel Wall Possessing a Compressible Core and Interacting with a Pulsating Viscous Liquid Layer

The paper deals with the formulation of a mathematical model to study a dynamics interaction of a three-layered channel wall with a pulsating viscous fluid layer in a channel. The narrow channel formed by two parallel walls was considered. The lower channel wall was a three-layered plate with a compressible core, and the upper one was absolutely rigid. The face sheets of the three-layered plate satisfied Kirchhoff's hypotheses. The plate core was considered rigid taking into account its compression in the transverse direction. Plate deformations were assumed to be small. The continuity conditions of displacements are satisfied at the layers' boundaries of the three-layered plate. The oscillations of the three-layered channel wall occurred under the action of a given law of pressure pulsation at the channel edges. The dynamics of the viscous incompressible fluid layer within the framework of a creeping motion was considered. The formulated mathematical model consisted of the dynamics equations of the three-layered plate with compressible core, Navier --- Stokes equations, and the continuity equation. The boundary conditions of the model were the conditions at the plate edges, the no-slip conditions at the channel walls and the conditions for pressure at the channel edges. The steady-state harmonic oscillations were investigated and longitudinal displacements and deflections of the plate face sheets were determined. Frequency-dependent distribution functions of amplitudes of plate layers displacements were introduced. These functions allow us to investigate the dynamic response of the channel wall and the fluid pressure change in the channel. The elaborated model can be used for the evolution of non-destructive testing of elastic three-layered elements contacting with a viscous fluid layer and being part of the lubrication, damping or cooling systems of modern instruments and units.

Peristaltic flow and heat transfer of nanofluids in a sinusoidal wall channel: two-phase analytical study

In this study, two-phase peristaltic nanofluid flow in two-dimensional wavy channel is modeled and the heat transfer analysis is performed for it. Both upper and lower channel walls are considered in a wavy shape by sinusoidal function. The governing equations are presented for the nanofluid based on the Buongiorno model and two analytical methods (least square method and differential transformation method). Maple 15.0 mathematical software is applied as the efficient solution methods for the governing equation. The effect of some parameters present in the governing equations (Brownian motion parameter, thermophoresis parameters, Grashof numbers and amplitude ratio of wavy channel), are discussed in terms of velocities, temperature and nanoparticles concentration functions. An important finding in this study is that, in order to have more nanoparticles concentration around the sinusoidal walls, thermophoresis parameter must be in lower values and vice versa.