Natural Convection セッション

Impact of MHD radiative flow of hybrid nanofluid over a rotating disk

White crystalline powder (aluminum oxide
 $$-\hbox {Al}_2\hbox {O}_3$$
 ) and water are the products often formed after the heating of aluminum hydroxide. In this report, boundary layer flow of two different nanofluids (i.e., 36 nm $$\hbox {Al}_2\hbox {O}_3$$
 -water and 47 nm $$\hbox {Al}_2\hbox {O}_3$$
 -water) over an upper horizontal surface of a paraboloid of revolution under the influence of magnetic field is presented. The combined influence of magnetic field strength, electric current density, electric charge, electron collision time, and the mass of an electron in the flows are considered in the governing equations. Three-dimensional transport phenomenon was considered due to the influence of the Lorentz force $$(\vec {F})$$
 along the z-direction as in the case of Hall currents. In this study, the dynamic viscosity and density of the nanofluids are assumed to vary with the volume fraction $$\phi$$
 . The dimensional governing equations were non-dimensionalization and parametrization using similarity variables. The corresponding boundary value problem was transformed into initial value problem using the method of superposition and solved numerically using fourth-order Runge–Kutta method with shooting technique (RK4SM). Magnetic field parameter is seen to have dual effects on the cross-flow velocity profiles of both nanofluids. The maximum cross-flow velocity is attained within the fluid domain when 36 nm nanoparticles alumina is used. The cross-flow velocity gradient at the wall increases with magnetic field parameter (M) and also increases significantly with Hall parameter at larger values of M.

Comparative analysis between 36 nm and 47 nm alumina–water nanofluid flows in the presence of Hall effect

This manuscript predicts the change in temperature at a different epilimnion to the change in temperature at a different hypolimnion. The fractional analysis on rotational second-grade fluid with sinusoidal boundary conditions is performed for knowing thermal stratification. The mathematical modeling is also proposed by means of modern fractional differential operators, namely Caputo–Fabrizio and Atangana–Baleanu derivatives, for rotational second-grade fluid. Most of authors have proposed the classical solutions of rotational second-grade fluid, which are obtained by the Laplace transform only. Our fractionalized mathematical model of rotational second-grade fluid has been solved via Fourier sine and Laplace transform techniques simultaneously. The solutions of velocity and temperature have been investigated and expressed in the format of Mittag–Leffler and Fox-H functions. Both fractional solutions are presented for comparison of velocity and temperature through Caputo–Fabrizio and Atangana–Baleanu derivatives. Finally, our results showed that the fractional solutions investigated for the velocity and temperature via Fourier sine and Laplace transform methods are stable and rapid than classical solutions.

Thermal stratification of rotational second-grade fluid through fractional differential operators

Significance of variability in magnetic field strength and heat source on the radiative-convective motion of sodium alginate-based nanofluid within a Darcy-Brinkman porous structure bounded vertically by an irregular slender surface

Understanding fluid flow, heat, and mass transfer over a stretching cylinder is essential in ascertaining the quality of wire coating and coper thinning. This study looks at the influence of the heat source, thermal radiation, chemical reaction, and natural convection of Carreau fluid flows over a vertical stretching cylinder immersed in a porous medium. Suitable similarity variables are applied to convert the partial governing equations arising in fluid flows, heat, and mass transfer into ordinary differential equations. The optimal homotopy analysis method is then utilized to solve the transformed highly nonlinear governing equations. The impacts of the relevant parameters such as the Weissenberg number, porosity, heat source parameter, radiative number, chemical reaction parameter, mixed convection parameter, and curvature parameter on the dimensionless velocity, temperature, and concentration distribution as well as for the skin friction, Nusselt number, and Sherwood number are discussed through graphs and tables. It is observed that the velocity shows an opposite behavior as compared to temperature, and concentration in shear-thinning, n 1 , and shear-thickening, n ≥ 1 , fluid for an increment of the Weissenberg number. Additionally, the thickness of the momentum, thermal, and concentration boundary layer is enhanced by the curvature of the cylinder.

Impact of chemical reaction, thermal radiation and porosity on free convection Carreau fluid flow towards a stretching cylinder

Non-coaxial rotation flow of MHD Casson nanofluid carbon nanotubes past a moving disk with porosity effect

Rotating effects and magnetohydrodynamic (MHD) free convection flow of second grade fluids in a porous medium is considered in this paper. It is assumed that the bounding infinite inclined plate has ramped wall temperature with the presence of heat and mass diffusion. Based on Boussinesq approximation, the analytical expressions for dimensionless velocity, temperature and concentration are obtained by using the Laplace transform method. All the derived solutions satisfying the involved differential equations with imposed boundary and initial conditions. The influence of various parameters on the velocity has been analyzed in graphs and discussed.

Second Grade Fluid for Rotating MHD of an Unsteady Free Convection Flow in a Porous Medium

https://www.techscience.com/cmc/v67n1/41152/pdf

Analysis of Magnetic Resistive Flow of Generalized Brinkman Type Nanofluid Containing Carbon Nanotubes with Ramped Heating

Non-coaxial rotation has wide applications in engineering devices, e.g. in food processing such as mixer machines and stirrers with a two-axis kneader, in cooling turbine blades, jet engines, pumps and vacuum cleaners, in designing thermal syphon tubes, and in geophysical flows. Therefore, this study aims to investigate unsteady free convection flow of viscous fluid due to non-coaxial rotation and fluid at infinity over an oscillating vertical plate with constant wall temperature. The governing equations are modelled by a sudden coincidence of the axes of a disk and the fluid at infinity rotating with uniform angular velocity, together with initial and boundary conditions. Some suitable non-dimensional variables are introduced. The Laplace transform method is used to obtain the exact solutions of the corresponding non-dimensional momentum and energy equations with conditions. Solutions of the velocity for cosine and sine oscillations as well as for temperature fields are obtained and displayed graphically for different values of time (t ), the Grashof number (Gr), the Prandtl number (
 $$\Pr $$
 ), and the phase angle (
 $$\omega t$$
 ). Skin friction and the Nusselt number are also evaluated. The exact solutions are obtained and in limiting cases, the present solutions are found to be identical to the published results. Further, the obtained exact solutions also validated by comparing with results obtained by using Gaver–Stehfest algorithm. The interested physical property such as velocity, temperature, skin friction and Nusselt number are affected by the embedded parameters time (t), the Grashof number (Gr), the Prandtl number (
 $$\Pr $$
 ), and the phase angle (
 $$\omega t$$
 ).

https://link.springer.com/content/pdf/10.1186%2Fs40064-016-3748-2.pdf

Ahmad Qushairi Mohamad

Papers

Impact of chemical reaction, thermal radiation and porosity on free convection Carreau fluid flow towards a stretching cylinder

Non-coaxial rotation flow of MHD Casson nanofluid carbon nanotubes past a moving disk with porosity effect

Second Grade Fluid for Rotating MHD of an Unsteady Free Convection Flow in a Porous Medium

Analysis of Magnetic Resistive Flow of Generalized Brinkman Type Nanofluid Containing Carbon Nanotubes with Ramped Heating

Exact solutions for unsteady free convection flow over an oscillating plate due to non-coaxial rotation