Heat transfer augmentation through engine oil-based hybrid nanofluid inside a trapezoid cavity

Heat transfer occurs as a result of density differences caused by temperature changes. It has several industrial applications. To improve performance, one must investigate the heat transfer behaviour of the working fluid. Hence, the purpose of this work is to report a heat transfer analysis of a partially heated trapezoid cavity filled with a hybrid nanofluid. The temperature conditions of the cavity are such that the bottom boundary is partially heated, inclined side boundaries are kept at a lower temperature, and the upper boundary is kept adiabatic. A trapezoidal shape heated obstacle is considered in the cavity’s centre. The heat transfer and flow take place inside the cavity due to density variation. The mechanism is regulated by mass, momentum, and energy conservation, as well as related boundary constraints. The solutions are determined by the use of a numerical technique known as the Finite Element Method after the governing equations are transformed into non-dimensional form, which brings up physical parameters affecting the heat transfer and flow. The initial study is performed for three types of nanofluids with silver and magnesium oxide nanoparticles inside water 2, kerosene , and engine oil . The study revealed that the engine oil-based hybrid nanofluid produced an increased heat transfer rate. Simulation is performed using engine-based hybrid nanofluid with the range of physical parameters, such as Rayleigh number (105≤≤107), Hartmann number (0≤≤100) and nanoparticles volume fraction (0≤≤0.2). It is found that the heat transfer rate is enhanced by increasing the fraction of nanoparticles in the base fluid. Moreover, imposition of magnetic field has reverse impact on the fluid movement

Photothermal excitation in non-local semiconductor materials with variable moisture thermal conductivity according to moisture diffusivity

In this work, a new model is described for the case of interference between thermal, plasma and elastic waves in a non-local excited semiconductor medium. The governing equations have been put under the influence of moisture diffusion in one dimension (1D) when the moisture thermal conductivity of the non-local medium is taken in variable form. Linear transformations were used to describe the dimensionless model. The photo-thermoelasticity theory according to moisture diffusivity was applied to describe the governing equations using Laplace transforms to obtain analytical solutions. In the time domain, complete solutions are obtained linearly when the conditions are applied (thermal ramp type and non-Gaussian plasma shock) to the surface through numerical methods of inverse Laplace transforms. Numerical simulation is used to display the basic physical quantities under study graphically. The current research has yielded several specific examples of great significance. Many comparisons are made under the influence of fundamental physical variables such as relaxation times, variable thermal conductivity, non-local parameters, and reference moisture parameters through graphing and describing them theoretically

Settling slip velocity of a spherical particle in an unbounded micropolar fluid

The gravitational settling of small spherical particles in an unbounded micropolar fluid with slip surfaces is considered. The motion is studied under the assumption of low Reynolds number. The slip boundary conditions on velocity and microrotation at the surface of the spherical particle is used. The solution for the stream function of the fluid flow is obtained analytically. The settling velocity is obtained and is plotted against the Knudsen number for various values of the micropolarity parameter and constants depending on the material of the solid surface. The problem of rotational motion of a particle with slip surface is also solved and the torque coefficient acting on the spherical particle is obtained and is plotted against Knudsen number for different values of micropolarity parameter, spin parameter, and the material constants. The correction to the Basset equation for settling velocity under gravity for slip particle in micropolar fluids is discussed with the range of Knudsen number which has been proven with known results available in the literature

Impact of slippage on the wall correction rotation factor of MHD couple stress fluid between two concentric spheres

The creeping rotational motion of a magnetohydrodynamic couple stress fluid between two concentric spheres under the impact of slippages. The slippage conditions are applied on the surface of the inside sphere. In addition, the couple stresses on the boundary are assumed to vanish. The analytical solution to the problem is used to obtain the field functions of velocity, tangential stress, and couple stresses. The wall correction factor experienced by the fluid on the inner solid sphere is evaluated and plotted. However, in the presence of a magnetic field, the eddy current caused by rotating particles produces a torque that tends to rise because the assumption of the torque direction is the opposite direction of magnetic induction. Also, the first couple stress parameter, the angular velocity ratio, and slip condition did an improvement in the torque. On the other side, the wall correction factor slows down with slippage on the inner sphere and the size parameter. All results give limiting cases with no slippage and viscous fluid

Effect of magnetic field on the motion of two rigid spheres embedded in porous media with slip surfaces

A semi-analytical study for the Stokes flow approximation caused by two solid spheres of different sizes with slip surfaces, immersed in a porous medium in the presence of a transverse magnetic field, is investigated. The two spheres are translating with different velocities along the line joining their centers. A general solution is developed from the superposition of the essential solutions in two spherical frameworks with origins located at the centers of the two spheres. Numerical results for the normalized hydrodynamic drag force acting on each sphere are obtained with good convergence for various values of the Hartmann number which characterizes the presence of magnetic field, the permeability parameter which characterizes the porous medium, separation parameter, and velocity and size ratios of the spheres. Our drag results are in good agreement with the available solutions in the literature in the cases of no-slip surfaces and when the porous medium turns into a pure fluid

Thermal-optical mechanical waves of the microelongated semiconductor medium with fractional order heat time derivatives in a rotational field

Abstract Outlined here is an innovative method for characterizing a layer of microelongated semiconductor material under excitation. Fractional time derivatives of a heat equation with a rotational field are used to probe the model during photo-excitation processes. Micropolar-thermoelasticity theory, which the model implements, introduces the microelongation scalar function to characterize the processes occurring inside the microelements. When the microelongation parameters are considered following the photo-thermoelasticity theory, the model investigates the interaction scenario between optical-thermo-mechanical waves under the impact of rotation parameters. During electronic and thermoelastic deformation, the key governing equations have been reduced to dimensionless form. Laplace and Fourier's transformations are used to solve this mathematical problem. Isotropic, homogeneous, and linear microelongated semiconductor medium's general solutions to their respective fundamental fields are derived in two dimensions (2D). To get complete solutions, several measurements must be taken at the free surface of the medium. As an example of numerical modeling of the important fields, we will use the silicon (Si) material’s physicomechanical characteristics. Several comparisons were made using different values of relaxation time and rotation parameters, and the results were graphically shown

Excited Non-Local Microelongated Semiconductor Layer Thermal-Optical Mechanical Waves Affected by Rotational Field

The main goal of this research is to provide a novel model that describes an optically heated layer of an excited non-local microelongated semiconductor material. In a rotating field, the model is examined as the photo-excitation processes occur. The model presents the microelongation scalar function, which describes the microelement processes according to the micropolar-thermoelasticity theory. The model analyses the interaction situation between optical-thermomechanical waves under the impact of rotation parameters when the microelongation parameters are taken into consideration according to the photo-thermoelasticity theory. During the electronic and thermoelastic deformation, the fundamental governing equations were obtained in dimensionless form, and they were investigated using the harmonic wave methodology. Two-dimensional general solutions for the fundamental fields of an isotropic, homogeneous, and linear non-local microelongated semiconductor medium are derived (2D). The free surface of the medium is subjected to several conditions to produce complete solutions due to the laser pulse. The physical properties of silicon (Si) material are used to show numerical modeling of the main fields. Some comparisons are made and graphically shown under the impact of various relaxation time and rotational parameters

Photo Thermal Diffusion of Excited Nonlocal Semiconductor Circular Plate Medium with Variable Thermal Conductivity

To examine the effects of the nonlocal thermoelastic parameters in a nanoscale semiconductor material, a novel nonlocal model with variable thermal conductivity is provided in this study. The photothermal diffusion (PTD) processes in a chemical action are utilized in the framework of the governing equations. When elastic, thermal, and plasma waves interact, the nonlocal continuum theory is used to create this model. For the main formulations to get the analytical solutions of the thermal stress, displacement, carrier density, and temperature during the nanoscale thermo-photo-electric medium, the Laplace transformation approach in one dimension (1D) of a thin circular plate is utilized. To create the physical fields, mechanical forces and thermal loads are applied to the semiconductor’s free surface. To acquire the full solutions of the research areas in the time-space domains, the inverse of the Laplace transform is applied with several numerical approximation techniques. Under the impact of nonlocal factors, the principal physical fields are visually depicted and theoretically explained

Elasto-thermoelectronic diffusion waves with changing thermal conductivity and thermal heating of microtemperature semiconductor

This paper presents a theoretical investigation of linear thermal conductivity temperature-dependent coupled elasto-thermoelectronic diffusion (ETD) waves in a micro-temperature semiconductor, specifically focusing on the effects of photo-excited processes. The governing equations are formulated for a semi-infinite silicon wafer, which serves as a semiconductor material. The explicit study of the strong coupling between the equations governing elastic wave transport, carrier (plasma) transport, and thermal wave transport is conducted in the presence of microtemperature influence. The electron–hole interaction is obtained within the framework of the ETD theory. Laplace transform is used to resolve the governing equations in a non-dimensional framework for thermoelastic and electronic deformation in one-dimensional (1D) scenarios. The present study employs the proposed model to analyze the impact of ramp-type heating on a stationary plane of unbounded semiconductor material. Thermoelastic electronic coupling is found to be affected by the presence of variable thermal conductivity and microtemperature parameters