Marangoni Convection Heat Research Articles

MHD Marangoni convection heat transfer of Ag-Cu hybrid nanofluid under a stretching/shrinking sheet with the effect of suction

This paper examines the heat transfer characteristics of magnetohydrodynamics (MHD), suction, and Marangoni convection under the stretching/shrinking Ag–Cu hybrid nanofluid surface flow. First, the governing partial differential equations (PDEs) were transformed into ordinary differential equations (ODEs), and the numerical result was obtained using the boundary value problem solver (bvp4c) in MATLAB. The development of the Nusselt number, the velocity profile and the temperature profile was plotted, discussed and inspected. Next, this paper undergoes stability analysis and heat transfer rate comparison between water, nanofluid and hybrid nanofluid. The dual solutions were observed, and the upper branch solution is determined to be stable. Compared to water, the heat transfer rates of Ag–Cu hybrid nanofluid and Cu nanofluid were accelerated by 2.84% and 2.75%, respectively.

Experimental and numerical investigations on combined Buoyancy–Marangoni convection heat and mass transfer of power-law nanofluids in a porous composite with complex surface

In this paper, a convection and heat transfer problem of power-law fluid in a three-dimensional porous media with complex surface is studied. The Buoyancy-Marangoni convection for non-Newtonian power-law fluids in porous media is solved using a compact high-order finite volume method. For this single-phase model, the left wall is kept at high temperature and high concentration, the right wall is affected by lower temperature and lower concentration, the upper wall is a complex surface, and the remaining walls are considered to be adiabatic and impermeable. The Weierstrass–Mandelbrot function is used to simulate the shape of the upper surface. The fluid in the porous cavity is a power-law nanofluids containing copper oxide nanoparticles. The solid material of the porous medium is aluminum foam. Numerical simulations can be used to determine the power law exponent, Marangoni number, Rayleigh number, and aspect ratio on the flow, heat transfer, and mass transfer rate.

Numerical study on combined buoyancy–Marangoni convection heat and mass transfer of power-law nanofluids in a cubic cavity filled with a heterogeneous porous medium

In this paper, the combined buoyancy–Marangoni convection of non-Newtonian power-law nanofluids in a 3D heterogeneous porous cubic cavity is investigated in detail with the compact high order finite volume method. Special attentions are given to detect the effects of heterogeneity level, Marangoni number, thermal Rayleigh number, buoyancy ratio and nanoparticle volume fraction on the fluid flow as well as on rates of heat and mass transfer. It is observed that as a result of the exponential distribution of the permeability, the heat and mass transfer rates reduce as the level of heterogeneity enhances. The effect of the surface tension on the heat and mass transfer intensity becomes insignificant when the buoyancy force is strengthened. Further, the average Nusselt and Sherwood numbers increase as the Marangoni number and thermal Rayleigh number increase due to the combined effects of buoyancy and surface tension. The augmentation of the buoyancy ratio causes convection heat and mass transfer to increase for the thermal dominated flow while decrease in buoyancy ratio also augments it for the solutal dominated flow. The heat transfer (mass transfer) rate is found to increase (decrease) with increasing the nanoparticle volume fraction. Moreover, for all above studied parameters, an intensification of the flow and an increase in average Nusselt and Sherwood numbers occur with the decrease in power-law index.

Unsteady Marangoni convection heat transfer of fractional Maxwell fluid with Cattaneo heat flux

Fractional shear stress and Cattaneo heat flux models are introduced in characterizing unsteady Marangoni convection heat transfer of viscoelastic Maxwell fluid over a flat surface. Governing equations and boundary condition are formulated firstly via the balance between the surface tension and shear stress. Numerical solutions are obtained by new developed numerical technique and some novel phenomena are found. Results shown that the fractional derivative parameters, Marangoni number and power law exponent have significant influence on characteristics velocity and temperature fields. As fractional derivative parameters increase, the temperature profiles rise remarkably and the viscoelastic effects of the fluid enhance with delayed response to surface tension, however the temperature profiles decline significantly with a thinner thickness of thermal boundary layer with the increase of Marangoni number. The average skin friction coefficient increases with the augment of Marangoni number, while the average Nusselt number decreases for larger values of power law exponent.

Marangoni Convection Heat and Mass Transport of Power-Law Fluid in Porous Medium with Heat Generation and Chemical Reaction

ABSTRACTThis article presents a study for Marangoni convection of power-law fluid in a porous medium driven by a power-law temperature and a power-law concentration with heat generation and first-order chemical reaction. It is assumed that the surface tension varies linearly with both the temperature and the concentration. The effects of power-law viscosity on temperature and concentration fields are taken into account bya modified Fourier law and Darcy's Law for power-law fluid. An approximate analytical solution is obtained using a homotopy analytical method, which is verified by numerical ones with good agreement. The transport characteristics of velocity, temperature, and concentration fields are analyzed in detail.

Marangoni abnormal convection heat transfer of power-law fluid driven by temperature gradient in porous medium with heat generation

In this paper we investigate Marangoni convection heat transfer of power-law fluids in porous medium with heat generation. The convection is driven by a temperature gradient that the surface tension is a quadratic function of the temperature. A new heat transfer constitutive equation is proposed based on N-diffusion proposed by Philip and the abnormal convection–diffusion model proposed by Pascal in which we assume that the heat diffusion depends non-linearly on both the temperature and the temperature gradient with modified Fourier heat conduction for power-law fluid. The governing partial differential equations are reduced to ordinary differential equations by suitable similarity transformations. Approximate analytical solution is obtained using homotopy analytical method (HAM) which is compared with numerical ones for particular cases in good agreement. The transport characteristics of velocity and temperature fields are analyzed in detail.

MHD thermosolutal marangoni convection heat and mass transport of power law fluid driven by temperature and concentration gradient

This paper studies the magnetohydrodynamic (MHD) thermosolutal Marangoni convection heat and mass transfer of power-law fluids driven by a power law temperature and a power law concentration which is assumed that the surface tension varies linearly with both the temperature and concentration. Heat and mass transfer constitutive equation is proposed based on N-diffusion proposed by Philip and the abnormal convection-diffusion model proposed by Pascal in which we assume that the heat diffusion depends non-linearly on both the temperature and the temperature gradient and the mass diffusion depends non-linearly on both the concentration and the concentration gradient with modified Fourier heat conduction for power law fluid. The governing equations are reduced to nonlinear ordinary differential equations by using suitable similarity transformations. Approximate analytical solution is obtained using homotopy analytical method (HAM). The transport characteristics of velocity, temperature and concentration fields are analyzed in detail.

Buoyant Marangoni convection of nanofluids in square cavity

The buoyant Marangoni convection heat transfer in a differentially heated cavity is numerically studied. The cavity is filled with water-Ag, water-Cu, water-Al2O3, and water-TiO2 nanofluids. The governing equations are based on the equations involving the stream function, vorticity, and temperature. The dimensionless forms of the governing equations are solved by the finite difference (FD) scheme consisting of the alternating direction implicit (ADI) method and the tri-diagonal matrix algorithm (TDMA). It is found that the increase in the nanoparticle concentration leads to the decrease in the flow rates in the secondary cells when the convective thermocapillary and the buoyancy force have similar strength. A critical Marangoni number exists, below which increasing the Marangoni number decreases the average Nusselt number, and above which increasing the Marangoni number increases the average Nusselt number. The nanoparticles play a crucial role in the critical Marangoni number.

Marangoni Convection Flow and Heat Transfer of Power Law Nanofluids Driven by Temperature Gradient with Modified Fourier's Law

Abstract We present a research for Marangoni convection heat transfer in power law nanofluids driven by temperature gradient. Four types of nanoparticles, namely Cu, Al2O3, CuO and TiO2 are considered by using power law CMC-water as a base fluid. The effects of power law viscosity on temperature field are taken into account by assuming that the temperature field is similar to the velocity field and the surface tension is assumed a quadratic function of the temperature. The governing partial differential equations are formulated and similarity solutions are obtained numerically using shooting method. The effects of the solid volume fraction, the Power law index and the Marangoni parameter on the velocity and temperature fields are analyzed and discussed in detail.

Magnetohydrodynamics Thermocapillary Marangoni Convection Heat Transfer of Power-Law Fluids Driven by Temperature Gradient

This paper presents an investigation for magnetohydrodynamics (MHD) thermocapillary Marangoni convection heat transfer of an electrically conducting power-law fluid driven by temperature gradient. The surface tension is assumed to vary linearly with temperature and the effects of power-law viscosity on temperature fields are taken into account by modified Fourier law for power-law fluids (proposed by Pop). The governing partial differential equations are converted into ordinary differential equations and numerical solutions are presented. The effects of the Hartmann number, the power-law index and the Marangoni number on the velocity and temperature fields are discussed and analyzed in detail.

Heat transfer mechanisms in vapor mushroom region of saturated nucleate pool boiling

To reveal the highly efficient heat transfer mechanisms in the vapor mushroom region of saturated nucleate pool boiling, a new model was developed in which three heat transfer mechanisms were considered: the conduction and evaporation in the microlayer region underneath vapor stem, the conduction and evaporation in the macrolayer region between the vapor mushroom and the heater surface and Marangoni convection in the macrolayer region. Two-dimensional conservation equations for laminar flow in the macrolayer region and conduction in the heater were solved. The SIMPLE-algorithm was used for handling the pressure–velocity coupling. Calculated boiling curve agrees well with the published experimental data and numerical results showed that about 60% heat flux is transferred by evaporation in the microlayer region, and about 40% heat flux is evaporated at the vapor–liquid interfaces of the macrolayer due to both the conduction and Marangoni convection heat transfer in the macrolayer region. Further investigations were also carried out for the cases in which only one or two heat transfer mechanisms were considered to assess the relative influences of the microlayer evaporation and Marangoni convection.