Increase In Thermal Boundary Layer Thickness Research Articles

Boundary layer flow with forced convective heat transfer and viscous dissipation past a porous rotating disk

The Coriolis effect with forced convective heat transfer on steady ferrohydrodynamic flow past a rotating porous disk in the presence of viscous dissipation has been investigated. The basic idea of the Neuringer-Rosensweig model has been used for the equation of motion of the nanofluid flow. With help of suitable transformations, the governing non-linear system of coupled partial differential equations is simplified into the dimensionless system of ordinary differential equations. Further, the dimensionless system of equations is solved numerically by the MATLAB routine bvp4c solver package. The findings for the motivating parameters of physical interest are expressed by the table and discussed with graphs. The outcomes show that heat transfer rate and thermal boundary layer thickness increase due to the higher value of the dissipation parameter.

Impact of induced magnetic field on thermal enhancement in gravity driven Fe3O4 ferrofluid flow through vertical non-isothermal surface

The ferrofluid are useful nanofluid and can be prepared by mixing magnetic types of nanoparticles in base fluid. The mathematical modelling of ferrofluid under induced magnetic field through a vertical stretching surface is formulated in the current theoretical study. The study is performed for ferrofluid by considering magnetite Fe3O4 magnetic nanoparticles in base fluid. In ferrofluid, the appropriate mixture of magnetic nanoparticles can lead to desire heat transfer phenomena. This theoretical study indicates that both Nusselt number and skin friction coefficient for Fe3O4-water ferrofluid increase by improving the effects of magnetic parameterβ. Velocity and magnetic boundary layer thicknesses increase/decrease for assisting/opposing flow by strengthening magnetic effects and in the presence of magnetic type Fe3O4 nanoparticle boundary layer thickness further enhances for pure water as compared to Fe3O4 type of ferrofluid. Temperature profile and thermal boundary layer thickness increase for both assisting/opposing flow with enhancing the concentration of Fe3O4 magnetic nanoparticle, however, thermal distribution reduces/upsurges in case of assisting/opposing flow with the increase of magnetic strength and thermal boundary layer thickness is greater for Fe3O4- water based ferrofluid as compared to regular fluid. The bvp4c built-in code in MATLAB software is employed for solution purposes. Results are displayed for the selection of effective parameters in data and graphical forms for both assisting and opposing flows.

Dual solutions for three-dimensional magnetohydrodynamic nanofluid flow with entropy generation

Abstract This paper presents a formulation for simulating magnetohydrodynamic three-dimensional convective flow and heat transfer in a nanofluid by incorporating the complete viscous dissipation function in the energy equation. A novel feature of this investigation of entropy generation and dual solutions is the use of the spectral quasilinearization method to solve the conservation equations. The results are compared with exact solutions or higher order solutions and a good agreement is achieved. The accuracy is determined by calculation of residual errors and the method of solution is shown to produce smaller residual errors than those achieved by the fifth-order Runge-Kutta Fehlberg method for nonlinear differential equations. The dual solutions for different Prandtl number, and Brownian motion and thermophoresis parameters are shown graphically and discussed. It is found that the temperature profiles as well as thermal boundary layer thickness increase with the Brownian motion parameter for first and the second solutions. The temperature profiles increase with the thermophoresis parameter for the first and second solutions. The entropy generation increases with the Reynolds number. Highlights Combined effects of entropy generation and MHD nanofluid are proposed. Spectral quasi-linearization method (SQLM) is used for computer simulations. Use axisymmetric stretching/shrinking sheet for dual solution. Validate the accuracy and convergence using residual error analysis.

Unsteady MHD slip flow of non Newtonian power-law nanofluid over a moving surface with temperature dependent thermal conductivity

In this paper, unsteady magnetohydrodynamic (MHD) boundary layer slip flow and heat transfer of power-law nanofluid over a nonlinear porous stretching sheet is investigated numerically. The thermal conductivity of the nanofluid is assumed as a function of temperature and the partial slip conditions are employed at the boundary. The nonlinear coupled system of partial differential equations governing the flow and heat transfer of a power-law nanofluid is first transformed into a system of nonlinear coupled ordinary differential equations by applying a suitable similarity transformation. The resulting system is then solved numerically using shooting technique. Numerical results are presented in the form of graphs and tables and the effect of the power-law index, velocity and thermal slip parameters, nanofluid volume concentration parameter, applied magnetic field parameter, suction/injection parameter on the velocity and temperature profiles are examined from physical point of view. The boundary layer thickness decreases with increase in strength of applied magnetic field, nanoparticle volume concentration, velocity slip and the unsteadiness of the stretching surface. Whereas thermal boundary layer thickness increase with increasing values of magnetic parameter, nanoparticle volume concentration and velocity slip at the boundary.

Stratified magnetohydrodynamic flow of tangent hyperbolic nanofluid induced by inclined sheet

This paper studies stratified magnetohydrodynamic (MHD) flow of tangent hyperbolic nanofluid past an inclined exponentially stretching surface. The flow is subjected to velocity, thermal, and solutal boundary conditions. The partial differential systems are reduced to ordinary differential systems using appropriate transformations. The reduced systems are solved for convergent series solutions. The velocity, temperature, and concentration fields are discussed for different physical parameters. The results indi- cate that the temperature and the thermal boundary layer thickness increase noticeably for large values of Brownian motion and thermophoresis effects. It is also observed that the buoyancy parameter strengthens the velocity field, showing a decreasing behavior of temperature and nanoparticle volume fraction profiles.

Effects of buoyancy and thermal radiation on MHD flow over a stretching porous sheet using homotopy analysis method

This paper investigates the theoretical influence of buoyancy and thermal radiation on MHD flow over a stretching porous sheet. The model which constituted highly nonlinear governing equations is transformed using similarity solution and then solved using homotopy analysis method (HAM). The analysis is carried out up to the 5th order of approximation and the influences of different physical parameters such as Prandtl number, Grashof number, suction/injection parameter, thermal radiation parameter and heat generation/absorption coefficient and also Hartman number on dimensionless velocity, temperature and the rate of heat transfer are investigated and discussed quantitatively with the aid of graphs. Numerical results obtained are compared with the previous results published in the literature and are found to be in good agreement. It was found that when the buoyancy parameter and the fluid velocity increase, the thermal boundary layer decreases. In case of the thermal radiation, increasing the thermal radiation parameter produces significant increases in the thermal conditions of the fluid temperature which cause more fluid in the boundary layer due to buoyancy effect, causing the velocity in the fluid to increase. The hydrodynamic boundary layer and thermal boundary layer thickness increase as a result of increase in radiation.

Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge–Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter.

Catalyzed combustion of H 2/air mixtures in a flat-plate boundary layer: I. Experimental results

A study has been made of the combustion characteristics of lean hydrogen-air mixtures flowing over a heated catalytic platinum plate. The objectives of the investigation were to develop a better understanding of the interaction between fluid mechanics, gas-phase combustion, and surface reaction in high-temperature surface-catalyzed combustion. The experimental system consisted of a thin quartz plate with vacuum-deposited platinum heating strips mounted over an open atmospheric-pressure jet of premixed hydrogen and air. Boundary-layer density profiles were measured using differential interferometry for flow visualization studies and Rayleigh scattering for point-density measurements. Laser Doppler velocimetry was also used to measure the velocity distribution. The presence of heat release due to surface reaction was determined from changes in heating-strip power inputs with fuel addition. Results were obtained for a range of equivalence ratios from 0.05 to 0.3 and plate surface temperatures from 470 to 1300 K. Significant surface heat release was found for all mixtures at plate temperatures as low as 470 K. At increased equivalence ratios and plate temperatures heat release due to gas-phase reaction was present. This was characterized by local increases in temperature across the boundary layer and an increase in thermal boundary-layer thickness. Comparisons with numerical calculations based on a surface reaction model which included finite-rate surface oxidation of H 2 and radical recombination indicated qualitative agreement in general boundary-layer behavior, but the predicted gas-phase heat-release rate was considerably higher than found experimentally.