Mixed Convection Flow Of Nanofluid Research Articles

Laminar Mixed Convective Nanofluid Flow in a Channel with Double Forward-Facing Steps: A Numerical Simulation Study

Predictions are reported for mixed convection using various types of nanofluids over forward-facing double steps in a duct. The continuity, momentum and energy equations are discretized and the simple algorithm is applied to link the pressure and flow fields inside the domain. Different types of nanoparticles Al2O3, CuO, SiO2 and ZnO, with different volume fractions in range of 1-4% and different nanoparticles diameter in the range of 20 – 80nm in base fluid (water) were used. Numerical investigations are conducted using finite volume method. In this study, different parameters such as the geometrical specifications (different steps heights in the range of h1= 0.01m-0.04m and h2 = 0.03m-0.06m for FFS) are used. Different Reynolds numbers in the range of 50-2000 (laminar flow) are investigated to identify their effects on the heat transfer and fluid characteristics. The results indicate that SiO2-water has the highest Nusselt number followed by Al2O3-water,Cuo-water and ZnO-water. The Nusselt number increases as the volume fraction increases but it decreases as the nanoparticles diameter increases. The velocity magnitude increases as the density of nanofluids decreases. The recirculation region and the Nusselt number increase as the step height, Reynolds number, and the volume fraction increase.

Group method analysis of mixed convection stagnation-point flow of non-Newtonian nanofluid over a vertical stretching surface

The group method analysis is applied to study the steady mixed convection stagnation-point flow of a non-Newtonian nanofluid towards a vertical stretching surface. The model utilized for the nanofluid incorporates the Brownian motion and thermophoresis effects. Applying the one-parameter transformation group which reduces the number of independent variables by one and thus, the system of governing partial differential equations has been converted to a set of nonlinear ordinary differential equations, and these equations are then computed numerically using the implicit finite-difference scheme. Comparison with previously published studies is executed and the results are found to be in excellent agreement. Results for the velocity, temperature, and the nanoparticle volume fraction profiles as well as the local skin-friction coefficient and local Nusselt number are presented in graphical and tabular forms, and discussed for different values of the governing parameters to show interesting features of the solutions.

A Similarity Solution for Mixed-Convection Boundary Layer Nanofluid Flow on an Inclined Permeable Surface

This paper concerns with calculation of heat transfer and pressure drop in a mixed-convection nanofluid flow on a permeable inclined flat plate. Solution of governing boundary layer equations is presented for some values of injection/suction parameter (f0), surface angle (γ), Galileo number (Ga), mixed-convection parameter (λ), volume fraction (φ), and type of nanoparticles. The numerical outcomes are presented in terms of average skin friction coefficient (Cf) and Nusselt number (Nu). The results indicate that adding nanoparticles to the base fluid enhances both average friction factor and Nusselt number for a wide range of other effective parameters. We found that for a nanofluid with φ = 0.6, injection from the wall (f0 = −0.2) offers an enhancement of 30% in Cf than the base fluid, while this growth is about 35% for the same case with wall suction (f0 = 0.2). However, increasing the wall suction will linearly raise the heat transfer rate from the surface, similar for all range of nanoparticles volume fraction. The computations also showed that by changing the surface angle from horizontal state to 60 deg, the friction factor becomes 2.4 times by average for all φ's, while 25% increase yields in Nusselt number for the same case. For assisting flow, there is a favorable pressure gradient due to the buoyancy forces, which results in larger Cf and Nu than in opposing flows. We can also see that for all φ values, enhancing Ga/Re2 parameter from 0 to 0.005 makes the friction factor 4.5 times, while causes 50% increase in heat transfer coefficient. Finally, we realized that among the studied nanoparticles, the maximum influence on the friction and heat transfer belongs to copper nanoparticles.

Numerical study of heat source/sink effects on dissipative magnetic nanofluid flow from a non-linear inclined stretching/shrinking sheet

This paper numerically investigates radiative magnetohydrodynamic mixed convection boundary layer flow of nanofluids over a nonlinear inclined stretching/shrinking sheet in the presence of heat source/sink and viscous dissipation. The Rosseland approximation is adopted for thermal radiation effects and the Maxwell-Garnetts and Brinkman models are used for the effective thermal conductivity and dynamic viscosity of the nanofluids respectively. The governing coupled nonlinear momentum and thermal boundary layer equations are rendered into a system of ordinary differential equations via local similarity transformations with appropriate boundary conditions. The non-dimensional, nonlinear, well-posed boundary value problem is then solved with the Keller box implicit finite difference scheme. The emerging thermo-physical dimensionless parameters governing the flow are the magnetic field parameter, volume fraction parameter, power-law stretching parameter, Richardson number, suction/injection parameter, Eckert number and heat source/sink parameter. A detailed study of the influence of these parameters on velocity and temperature distributions is conducted. Additionally the evolution of skin friction coefficient and Nusselt number values with selected parameters is presented. Verification of numerical solutions is achieved via benchmarking with some limiting cases documented in previously reported results, and generally very good correlation is demonstrated. This investigation is relevant to fabrication of magnetic nanomaterials and high temperature treatment of magnetic nano-polymers.

Mixed convection peristaltic flow of Eyring-Powell nanofluid in a curved channel with compliant walls

The novel features of nanofluids made them potentially significant in heat transfer mechanism occurring in medical and industrial processes like microelectronics, pharmaceutical processes, hybrid engines, thermal management of vehicles, refrigerator, chiller, gas temperature reduction and so forth. These processes bear tendency to enhance thermal conductivity and the convective heat transfer more efficiently than base fluid. This unique aspect made nanofluids the topic of interest in recent time via different fluid flow models. The problem in hand is one such application of nanofluids in peristaltic flow through curved channel. Thus peristalsis of Eyring-Powell nanofluid followed through conservation principles of mass, momentum, energy and concentration has been modeled. The whole system is made coupled via viscous dissipation, mixed convection, thermophoresis and Brownian motion. The complexity of system has been executed through a numerical approach after utilizing small Reynolds number and large wavelength concepts. A striking feature of this study is the activation of velocity and temperature with larger Brownian diffusion, whereas reduction is noticed with advancement in thermophoresis. Moreover the numerically obtained results for compliant walls are compatible with those obtained through other techniques.

Thermal and solutal stratification in mixed convection three-dimensional flow of an Oldroyd-B nanofluid

Abstract This paper investigates the double stratified effects in mixed convection three-dimensional flow of an Oldroyd-B nanofluid. The flow is due to a bidirectional stretching surface. Mathematical analysis is carried out using the temperature and concentration stratification effects. Brownian motion, thermophoresis and chemical reaction effects are also considered. The governing nonlinear boundary layer equations are first converted into the dimensionless ordinary differential equations and then solved for the convergent series solutions of velocity, temperature and nanoparticles concentration. Convergence analysis of the obtained series solutions is also checked and verified. Effects of various emerging parameters are studied in details. Numerical values of local Nusselt and Sherwood numbers are tabulated and analyzed. It is noticed that the impact of mixed convection parameter on temperature and nanoparticles concentration is quite similar. Both temperature and nanoparticles concentration are reduced for larger mixed convection parameter.

Thermal radiation impact in mixed convective peristaltic flow of third grade nanofluid

Abstract This paper models the peristaltic transport of magnetohydrodynamic (MHD) third grade nanofluid in a curved channel with wall properties. Combined effects of heat and mass transfer are retained via mixed convection. The present analysis is made in the presence of thermal radiation and chemical reaction. No-slip effect is maintained at the boundary for the velocity, temperature and nanoparticle volume fraction. Resulting formulation is simplified by employing the assumptions of long wavelength and low Reynolds number approximations. Results of axial velocity, temperature, nanoparticle mass transfer and heat transfer are studied graphically. Results reveal increment in fluid velocity for larger values of heat transfer Grashof number. There is reduction in nanoparticle mass transfer with the increase in thermophoresis parameter.

Effects of inclination angle on mixed convective nanofluid flow in a double lid-driven cavity with discrete heat sources

In the present study, numerical simulations are performed to examine the effect of inclination angle on the heat transfer of Al2O3–water nanofluid for mixed convection flows in a partially heated double lid driven inclined cavity. At the lower wall of the cavity, two heat sources are fixed with the condition that the remaining part of the bottom wall is kept insulated. Top wall and vertically moving walls are maintained at constant cold temperature. Buoyant force is responsible for the flow along with two moving vertical walls. The governing equations are discretized with the help of finite element method in space and the Crank–Nicolson in time. For the spatial discretization, nonconforming Stokes element Q∼1/Q0 of 2nd order accuracy for velocity, temperature and 1st order accuracy for pressure is utilized. The discretized nonlinear systems of equations are treated by using the Newton method and the associated linear subproblems are solved using Gaussian elimination method in each time level. Numerical results are presented and analyzed by means of streamlines, isotherms, tables and some useful plots. Impact of emerging parameters on the flow, in specific ranges such as Reynolds number (1⩽Re⩽100), Richardson number (0.01⩽Ri⩽10), nanoparticle volume fraction (0⩽ϕ⩽0.04) as well as inclination angle of cavity (0°⩽γ⩽45°) are investigated and findings are exactly of the same order as that of the previously performed analysis in the literature. Calculations of average Nusselt number, average temperature, average entropy generation due to heat transfer and fluid friction and kinetic energy are the main focus of our study.

Mixed convection nanofluid flow over microscale forward-facing step — Effect of inclination and step heights

A numerical study of nanofluid flow and heat transfer of laminar mixed convection flow over a three-dimensional, horizontal microscale forward-facing step (MFFS) is reported. The effects of different step heights and the duct inclination angle on the heat transfer and fluid flow are discussed in this study. The straight and downstream walls were heated to a constant temperature and uniform heat flux respectively. The numerical results were carried out for step heights of 350μm, 450μm, 550μm and 650μm. Different inclination angles were considered to determine their effects on the flow and heat transfer. Ethylene glycol-SiO2 nanofluid is considered with a 25nm particle diameter and 4% volume fraction. The results reveal that the Nusselt increases as the step heights increase. Additionally, no significant effect of the duct inclination angle is found on the heat transfer rate and the fluid flow.

Mixed convective peristaltic transport of Carreau-Yasuda nanofluid in a tapered asymmetric channel

Here modeling and analysis for mixed convective peristaltic flow of Carreau-Yasuda nanofluid have been carried out. The asymmetric channel walls are tapered. Effects of Brownian motion and thermophoresis are taken into consideration. The flow equations for the relevant problem are first constructed and then non-dimensionalized. The resulting non-linear coupled systems subject to lubrication approach are solved. Graphs reflecting the variations of pertinent parameters on the velocity, temperature, nanoparticle volume fraction are examined. Shear stress distribution and pumping and trapping phenomena are discussed. Results indicate that amplitude of shear stress decreases for larger Weissenberg number and power-law index whereas it enhances through viscosity ratio parameter.

A model for an application to biomedical engineering through nanoparticles

Recent advancements in nanoscience and technology has made the nanofluid an important research topic. Various models have been put forward to estimate the effective thermal conductivity of nanofluids. Present article addresses the comparative study of Maxwell’s and Hamilton–Crosser’s model for mixed convection peristaltic flow of incompressible nanofluid in an asymmetric channel. Viscous dissipation and heat generation/absorption effects are retained. Analysis is performed for five different types of nanoparticles namely titanium oxide or titania (TiO2), aluminum oxide or alumina (Al2O3), copper oxide (CuO), copper (Cu) and silver (Ag) with water as base fluid. Velocity and thermal slip conditions are employed. Lubrication approach is adopted for problem formulation. The developed non-linear problems are solved numerically. Plots for axial velocity, temperature and heat transfer rate at the wall are obtained and analyzed.

Impact of double stratification and magnetic field in mixed convective radiative flow of Maxwell nanofluid

This article is devoted to the numerical and series solutions of magnetohydrodynamic steady flow of Maxwell fluid with nanoparticles. Double stratification effects in the presence of thermal radiation are employed in the thermal and nanoparticle mass species expressions. The governing nonlinear systems of equations are coupled through mixed convection. A numerical algorithm namely shooting technique is employed to find the numerical solutions of velocity, temperature and nanoparticle concentration. The series solutions are obtained via homotopic criteria. The velocity, temperature and nanoparticle concentration for various values of physical parameters are presented and discussed. Comparison of homotopic and numerical solutions with previous published work is computed in a limiting sense.

Unsteady mixed convection squeezing flow of nanofluid between parallel disks

In this article, mixed convection squeezing flow of a nanofluid between parallel disks is considered. The partial differential equations governing the flow problem are converted into coupled system of ordinary differential equation with the help of suitable similarity transforms. Homotopy analysis method is employed to solve the coupled system of ordinary differential equations. The influence of involved parameters, on velocity, temperature, and concentration profile, is presented graphically coupled with detailed discussion. The results for skin friction coefficient and Nusselt and Sherwood numbers are also a part of this study. Numerical solution is also obtained with the help of Runge–Kutta method of order 4. An excellent agreement is found between analytical and numerical solutions. From the results obtained, we observe that the skin friction coefficient decreases with increasing squeeze number for the case of injection and increases with increase in squeeze number for the case of injection at the walls. Furthermore, Nusselt number gets a rise with increment in squeeze number for the case of injection at the wall and a drop in Nusselt number for the case of suction at the wall is observed when there is suction at the wall. Sherwood number is seen to drop quite steeply with higher values of squeeze number for the injection case and a rise in Sherwood number for the suction is observed when there is suction at the wall.

Hydromagnetic Mixed Convective Nanofluid Slip Flow past an Inclined Stretching Plate in the Presence of Internal Heat Absorption and Suction

The steady two-dimensional mixed convective boundary layer flow of nanofluid over an inclined stretching plate with the effects of magnetic field, slip boundary conditions, suction and internal heat absorption have been investigated numerically. Two different types of nanoparticles, namely copper and alumina with water as the base fluid are considered. Similarity transformations are employed to transform the governing nonlinear partial differential equations into coupled non-linear ordinary differential equations. The influence of pertinent parameters such as magnetic interaction parameter, angle of inclination, volume fraction, suction parameter, velocity slip parameter, thermal jump parameter, heat absorption parameter, mixed convection parameter and Prandtl number on the flow and heat transfer characteristics are discussed. A representative set of results are displayed graphically to illustrate the issue of governing parameters on the dimensionless velocity and temperature. Numerical values of skin friction coefficient and the Nusselt number are shown in tabular form. A comparative study between the previously published work and the present results in a limiting sense reveals excellent agreement between them.

Shape effect of nanosize particles in unsteady mixed convection flow of nanofluid over disk with entropy generation

The aim of this paper is to study the different shapes of nanoparticles on mixed convective steady flow over a rotating disk. For nanofluid, the copper nanoparticles of disk, cylindrical, and spherical shapes of different sizes and water as base fluid are considered. The physical problem is first modeled and then the governing equations are transformed into nonlinear ordinary differential equations. These equations are dimensionless using geometrical and physical flowfield-dependent parameters and solved analytically. A very good agreement is observed between the obtained results of the current study and previously published study in limiting cases. The shape effects on velocity profiles in radial, tangential, axial directions, and temperature distribution are displayed graphically with the reflection of specific range of nanolayer thickness and its conductivity. In addition, irreversibility due to heat and fluid friction is investigated that supports the heat transfer enhancement in renewable energy systems and industrial thermal management. For the analysis of the averaged entropy generation number, the results are shown in pie charts and tablet form. It is evident from the study that proper choice of nanoparticles will be helpful in controlling velocity and heat transfer. It is also observed that irreversibility process can be reduced by using nanoparticles, especially the spherical particles.

A comparative study of mixed convection and its effect on partially active thermal zones in a two sided lid-driven cavity filled with nanofluid

In the present study, a two sided lid-driven mixed convection nanofluid flow with discrete heat sources have been numerically investigated. A two dimensional computational visualization technique is used to study the flow behavior using four different cases; depending on the direction of moving vertical walls with fixed upper and lower walls. Two discrete heat sources of equal lengths are taken on the lower wall and the rest of it is kept insulated. The other walls are kept at constant low temperature. The effect of flow governing parameters such as Reynolds number 1⩽Re⩽100, Richardson number 0.1⩽Ri⩽10 and solid volume fraction 0.0⩽ϕ⩽0.2 with Prandtl number Pr=6.2 is studied to understand the fluid flow pattern and the heat transfer effect using isotherms and average Nusselt number.

Effects of Magnetic Field on an Unsteady Mixed Convection Flow of Nanofluids Containing Spherical and Cylindrical Nanoparticles

The present article gives a ray of light on the effects of magnetic field on an unsteady mixed convection flow of nanofluids containing nanoparticles which are spherical and cylindrical in nature. The unsteadiness in the flow is mainly caused by time dependent stretching velocity and temperature of the sheet at the surface. The governing transportation equations are first transformed into ordinary differential equations by using similarity transformations and then solved by employing Runga–Kutta–Frelberg method with shooting technique. The influence of various parameters on velocity and temperature profiles as well as wall shear stress and the rate of mass transfer are discussed through graphs and tables. The results for regular fluid (water) from the study are in excellent agreement with the results reported in the literature.

Hydromagnetic mixed convection flow of copper and silver water nanofluids due to a curved stretching sheet

Main objective of present analysis is to study the MHD mixed convection flow of nanofluid due to a curved stretching sheet. Water based nanofluid comprising copper and silver as nanoparticles is used. Heat transfer analysis is carried out in the presence of Joule heating and nonlinear thermal radiation. Similarity transformations are used to obtain the system of nonlinear ordinary differential equations. Convergent series solutions are obtained. Effects of different variables on velocity and temperature are examined. Skin friction coefficient and Nusselt number are examined and analyzed for the influence of different involved parameters.

Mixed convective radiative flow of second grade nanofluid with convective boundary conditions: An optimal solution

We have studied three dimensional second grade nanofluid flow with effects of thermal radiation and mixed convection over an exponential stretched surface under the influence of convective boundary conditions. Obtained partial differential equations are transformed into coupled differential equations with the aid of apposite transformations. Newly introduced BVPh 2.0 Mathematica package is used to obtain an optimal convergent solution. This method is more efficient to provide optimal convergent value for all involved fields unlike Homotopy analysis method (HAM) which provide a rough estimate of convergence region. Impact of incipient physical parameters on velocity, temperature and concentration fields is presented in the form of graphs and debated accordingly. Numerical tabulated values of skin friction coefficient, local Nusselt and Sherwood numbers with requisite discussion against numerous parameters is also added. It is noticed that temperature field is higher for larger values of radiation parameter. Moreover, increase in temperature profile and decrease in concentration field against gradually mounting values of Brownian motion parameter are experienced.

Numerical simulation and parametric study of laminar mixed convection nanofluid flow in flat tubes using two phase mixture model

In this article, the laminar mixed convection of Al2O3-Water nanofluid flow in a horizontal flat tube has been numerically simulated. The two-phase mixture model has been employed to solve the nanofluid flow, and constant heat flux has been considered as the wall boundary condition. The effects of different and important parameters such as the Reynolds number (Re), Grashof number (Gr), nanoparticles volume fraction (Φ) and nanoparticle diameter (dp) on the thermal and hydrodynamic performances of nanofluid flow have been analyzed. The results of numerical simulation were compared with similar existing data and good agreement is observed between them. It will be demonstrated that the Nusselt number (Nu) and the friction factor (Cf) are different for each of the upper, lower, left and right walls of the flat tube. The increase of Re, Gr and f and the reduction of dp lead to the increase of Nu. Similarly, the increase of Re and f results in the increase of Cf. Therefore, the best way to increase the amount of heat transfer in flat tubes using nanofluids is to increase the Gr and reduce the dp.