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"Al Rashed, Abdullah"
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An unstoppable force : the art of ARC
This is the first monograph for Saudi artist Abdullah Rashed AlSahli (ARC), who makes whimsical digital artworks reflecting on his rare progressive disease. He is also the founder of Art Without Limits (AWL), an art studio focusing on empowering artists with disabilities.
Book
Effect of a porous medium on flow and mixed convection heat transfer of nanofluids with variable properties in a trapezoidal enclosure
In the present study, the flow field and heat transfer of a water–copper nanofluid with variable properties in a trapezoidal enclosure saturated with porous media are studied. The governing equations are solved by finite volume method and the SIMPLER algorithm. The nanofluid flow is assumed to be laminar, steady and incompressible. Simulations are performed for sidewall (trapezoid legs) angles of 30°, 45° and 60° with respect to horizontal axis, Reynolds numbers from 10 to 1000, Darcy numbers of 10−2, 10−3, 10−4 and volume fractions of 0 to 0.04 of nanoparticles. Numerical results show that the average Nusselt number increases with increasing volume fraction of nanoparticles for all studied Darcy numbers. The convection and motion of the nanofluid decrease by reducing the Darcy number which leads to a reduction in the velocity and local Nusselt number. The average Nusselt number increases by increasing the Darcy number for all aspect ratios. Also, the average Nusselt number increases with increasing Reynolds number for all Darcy numbers, aspect ratios and volume fractions of nanoparticles.
Journal Article
Simplified finite element algorithm to solve conjugate heat and mass transfer in porous medium
Purpose
The purpose of this paper is to highlight the advantages of a simplified algorithm to solve the problem of heat and mass transfer in porous medium by reducing the number of partial differential equations from four to three.
Design/methodology/approach
The approach of the present paper is to develop a simplified algorithm to reduce the number of equations involved in conjugate heat transfer in porous medium.
Findings
Developed algorithm/method has many advantages over conventional method of solution for conjugate heat transfer in porous medium.
Research limitations/implications
The current work is applicable to conjugate heat transfer problem.
Practical implications
The developed algorithm is useful in reducing the number of equations to be solved, thus reducing the computational resources required.
Originality/value
Development of simplified algorithm and comparison with conventional method.
Journal Article
Effects of Movable-Baffle on Heat Transfer and Entropy Generation in a Cavity Saturated by CNT Suspensions: Three-Dimensional Modeling
Convective heat transfer and entropy generation in a 3D closed cavity, equipped with adiabatic-driven baffle and filled with CNT (carbon nanotube)-water nanofluid, are numerically investigated for a range of Rayleigh numbers from 103 to 105. This research is conducted for three configurations; fixed baffle (V = 0), rotating baffle clockwise (V+) and rotating baffle counterclockwise (V−) and a range of CNT concentrations from 0 to 15%. Governing equations are formulated using potential vector vorticity formulation in its three-dimensional form, then solved by the finite volume method. The effects of motion direction of the inserted driven baffle and CNT concentration on heat transfer and entropy generation are studied. It was observed that for low Rayleigh numbers, the motion of the driven baffle enhances heat transfer regardless of its direction and the CNT concentration effect is negligible. However, with an increasing Rayleigh number, adding driven baffle increases the heat transfer only when it moves in the direction of the decreasing temperature gradient; elsewhere, convective heat transfer cannot be enhanced due to flow blockage at the corners of the baffle.
Journal Article
Characterization of the nanoparticles, the stability analysis and the evaluation of a new hybrid nano-oil thermal conductivity
The present study aims at nanoparticles characterization and stability as well as the thermal conductivity of the hybrid nano-oil of ZnO–MWCNT/oil at the temperature range from 25 to 65 °C and the concentrations range from 0.50 to 3.2% for the solid particles. First, the nanoparticles of MWCNT and ZnO were characterized using XRD-FESEM and FTIR tests, and according to the results, the analysis of atomic, surface and chemical structure of nanoparticles was made. The nanolubricant was prepared by a two-step method. For this purpose, firstly, the stability was analyzed by the DLS test and the results show that the nanoparticles are in nanoscale after the construction of nano-oil. The thermal conductivity was measured based on the variables of temperature and volume fraction. An increasing trend was observed for the thermal conductivity for higher temperature and volume fraction of the nanoparticles. The biggest improvement of the thermal conductivity compared to the base fluid is at 65 °C, the volume fraction is 3.2%, and its value is 35.1%. Moreover, a very accurate experimental relationship was developed to determine the ratio of the thermal conductivity of nano-oil in the empirical range.
Journal Article
Conjugate Heat Transfer in an Annulus with Porous Medium Fixed Between Solids
Conjugate heat transfer is an important area of research which has been in demand due to its applications related to various scientific and engineering fields. The current research is focused to study the heat transfer in a porous medium sandwiched between two solid walls of an annular vertical cylinder. The prime focus of the current study was to evaluate the effect of solid wall thickness, the influence of variable wall thickness at inner and the outer radius, the conductivity ratio and the solid wall conductivity ratio on the heat transfer characteristics of the porous medium. The surface at inner and outer radii of the annulus is maintained isothermally at
T
h
and
T
∞
such that
T
h
>
T
∞
. The governing partial differential equations for the conjugate heat transfer in porous medium and that of solid walls are converted into a set of algebraic equations with the help of finite element method and then solved simultaneously to predict the temperature variation in the solid wall as well as the porous region of the annular domain.
Journal Article
Three-dimensional analysis of natural convection in nanofluid-filled parallelogrammic enclosure opened from top and heated with square heater
A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side. Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05, inclination angle of the back and front walls (α) from 5° to 75°, Rayleigh number from 103 to 105, and length of heater changer from 0.1 to 1. The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.
Journal Article
Heat transfer analysis in an annular cone subjected to power law variations
Present study deals with the analysis of heat transfer and fluid flow behavior in an annular cone fixed with saturated porous medium. The inner surface of the cone is assumed to have power law variable wall temperature. The governing partial differential equations are solved using well known Finite Element Method (FEM). The coupled nonlinear differential equations are converted into the algebraic equations by using Galerkin method. A 3 noded triangular element is used to divide the porous domain into smaller segments. The effects of various geometrical parameters on the cone angle are presented. It is found that the effect of cone angle on the heat transfer characteristics and fluid flow behavior is considerably significant. The fluid moment is found to shift towards the upper side of cone with increase in the power law coefficient. The fluid velocity decreases with increase in the power law coefficient.
Journal Article
Computational study of natural convection and entropy generation in 3-D cavity with active lateral walls
Numerical simulation of the natural convection and entropy generation in an air-filled cubical cavity with active lateral walls is performed in this work. Both the lateral front and right sidewalls are maintained at an isothermal cold temperature. While an isothermal hot temperature is applied for both the lateral back and left sidewalls. The upper and lower walls are kept adiabatic. Entropy generation rates due to the fluid friction and the heat transfer are simulated by using the Second law of thermodynamics. Results are illustrated for Rayleigh numbers varied from (103 ? Ra ? 106). It was shown that the increase in the Rayleigh number leads to increase the average Nusselt number and to decrease the Bejan number. Also, it was found that both, Sth, and Stot, increase slightly with the increase in Rayleigh number until they reach (Ra = 105) and then begin to jump after this value. After (Ra = 105), the increase in both, Stot, and Sfr, is greater than Sth. Moreover, it was observed that iso-surfaces of Stot are similar to Sth at (103 ? Ra ? 105), while they are similar to Sfr at high Rayleigh number. nema
Journal Article
Electro-thermo-convection in dielectric liquid subjected to partial unipolar injection between two eccentric cylinders
Purpose
The purpose of this work is to highlight the effects of partial unipolar injection on electro-thermo-convection (ETC) in dielectric liquid contained between two eccentric cylinders.
Design/methodology/approach
A finite volume method was used to solve governing equations. The study is performed for different parameters, such as radius ratio (0.2 ≤ Γ ≤ 0.6), dimensionless electric Rayleigh number (0 ≤ T ≤ 900), eccentricity (−0.4 ≤ e ≤ 0.4) and thermal Rayleigh number (10 ≤ Ra ≤ 5.105).
Findings
It is found that heat transfer increases with increase in dimensionless electric Rayleigh number and eccentricity ratio.
Originality/value
The originality of this work is to analyze the ETC in dielectric liquid subjected to partial unipolar injection between two eccentric cylinders
Journal Article