Al-Qadisiyah Journal for Engineering Sciences

Abstract An innovative experimental approach was developed to enhance NaCl removal using porous broad-crested weirs with different alumina-limestone configurations in an open-channel flow under controlled hydraulic conditions. Eight experimental cases were systematically evaluated, examining pure limestone, pure alumina, and mixed arrangements (Al-Ls-Al, Ls-Al-Ls) under two flow rates over 240 minutes. Results demonstrate that pure alumina achieved superior performance with 5.88\% average removal efficiency, significantly outperforming pure limestone (2.01-4.27\%) and mixed configurations (4.41-5.01\%). Limestone exhibited significant hydraulic dependency, with removal efficiency increasing by 112\% when flow rate increased from through flow to through flow limit conditions, while alumina demonstrated consistent performance across both flow regimes. All configurations showed initial rapid removal followed by a gradual approach toward equilibrium efficiency, with the most significant removal occurring within the first 10 minutes. Mixed material configurations (Al-Ls-Al and Ls-Al-Ls) achieved removal efficiencies that fell between those of pure materials, indicating no enhancement beyond the individual material properties. The study reveals that while alumina provides optimal NaCl removal, limestone under enhanced flow rates offers economically viable alternatives, achieving 71\% of alumina's performance. Porous broad-crested weirs represent promising technology for sustainable water treatment applications.

Abstract This work examines the two-dimensional continuous flow of a Casson-Williamson fluid over a stretched surface under a Darcy-Forchheimer permeable medium. Several elements can affect the flow, including Joule heating, radiation, chemical reactions, thermal sources, electric field influences, and magnetic field influences. Nonlinear partial differential equations articulate the fundamental equations governing the system's dynamics in this physical model. We simplify these equations to a system of nonlinear ordinary differential equations by applying requisite changes. The Keller Box technique is utilized to simplify this collection of ordinary differential equations. Velocity, temperature and concentration graphs are plotted. The velocity profiles decline with a rise in the Casson parameter, magnetic parameter, porous parameter, Weissenberg number, and velocity slip parameter. Still, the electric field parameter diminishes when the speed slip constraint is enhanced. This study primarily examines several local properties, including the skin resistance coefficient, the Nusselt number, and the Sherwood numbers. We compare our results with the current literature by computing the skin friction coefficient for different inputs of the Casson factor. Prior studies have yielded results that are fairly congruent with this one.

Abstract The work aims to investigate the MHD Casson fluid flow over an exponentially long sheet via a thermally stratified permeable medium. All facets of chemical processes, Joule heating, and exponential heat sources are covered in this subject. By using the appropriate similarity conversions, the leading partial differential equations (PDEs) of the model are transformed into a set of nonlinear ordinary differential equations (ODEs). The description of the previous technique was made simpler by applying the Keller Box methodology. The results reveal that when the viscosity factor is increased, the velocity profile improves, but when the thermal profile improves, the opposite trending impact is evident. The temperature profile exhibits the opposite tendency, despite a decline in the number of observations of the Casson fluid constraint. Joule heating parameters allow for more precise measurements of the heat source's properties by raising the temperature. The concentration graph shows a reduction as the number of observations for the chemical reaction parameter increases. The validity of the problem is investigated by computing the Nusselt number for cumulative Prandtl number observations and comparing the results with the literature.

Abstract The present study, experimentally investigated the mixed convection in a square enclosure partitioned in two layers. The experiments were performed with Al₂O₃–water nanofluid (upper layer) and superposed porous medium (lower layer) with an adiabatic rotating cylinder at the center of the cavity. The boundary conditions of the experimental study were; the upper and lower walls were assumed adiabatic, the right wall was heated, and the left wall was cooled. Experimentally, 15 K-type thermocouples and thermal imaging camera were employed to measure the temperatures distribution inside the cavity when the concentration of nanoparticles (ɸ = 0.06), the temperature difference (∆T) between the cold and hot walls was (6, 8, and 10) °C, and angular rotational velocity (-50, -25, 0, 25, and 50) rpm. The results of experimental data showed that in general, the distribution of temperatures was very well along the upper half of the enclosure, while in the lower half the temperature distribution was confined near the hot wall region. When the circular cylinder rotates in counter-clockwise, it noted that the effect of speed is evident in the downside of the cylinder, while the temperature distribution in the left upper part of the enclosure decreasing. When the circular cylinder rotates in the clockwise direction, the results showed that the effect of cylinder rotation was around cylinder only. Moreover, the results demonstrated that the increasing temperature difference leads to a noticeable increment in the intensity of the flow.

Abstract Natural convection fluid flow and heat transfer of fluid-saturated porous media heated by an internal circular cylinder inside a wavy enclosure is investigated numerically. The 2D enclosure is composed of two isothermal vertical wavy walls and two adiabatic horizontal flat walls. Darcy assumption and Boussinesq approximation were relied on in this steady, incompressible study. The governing equations were solved using Galerkin finite element method implemented in FlexPDE software package. The performance of enclosure was evaluated by three non-dimensional parameters namely, the Darcy-modified Rayleigh number Ram (100-1000), the waviness ratio λ (0-0.35), and the position of the inner heated cylinder ξ (0.45-1.05). The results were presented by visualization of the streamline and isothermal contours and by the local and average Nusselt numbers. It was found that the lower the position of the inner cylinder (ξ=0.45) is the largest the values of Nusselt number while the influence of the wall waviness ratio is found to be very small.