Ahmed BAHLAOUI - Academia.edu (original) (raw)

Papers by Ahmed BAHLAOUI

Computational Thermal Sciences: An International Journal

In this article, we examined the passive cooling techniques built into a building in hot temperat... more In this article, we examined the passive cooling techniques built into a building in hot temperate climate. Our work aims to reduce the energy demand for cooling and progress the thermal comfort of building by decreasing overheating hours. The dynamic simulations of the energy performance in a building with an earth-air heat exchanger (EAHX) are performed in the summer period using TRNSYS software. The building is situated in Beni Mellal city (Morocco) where the climate is a hot temperate one. The results of the simulations show a significant potential for air cooling. Indeed, for the hottest day of July (retained for this study), when the outside temperature is 44.8 °C and the cooled temperature (inside) is 29 °C, the difference of 15.8 °C is obtained. Also, an evaluation of the relative humidity is provided. Finally, we recommend that the Moroccan thermal code encourage the use of passive cooling techniques; precisely in temperate climate.

2020 IEEE 2nd International Conference on Electronics, Control, Optimization and Computer Science (ICECOCS)

The 3D printing technology allows to overcome the lack of medical equipment during the Covid19 pa... more The 3D printing technology allows to overcome the lack of medical equipment during the Covid19 pandemic around the world. The PLA is widely used to produce medical devices and personal protective equipment. The aim of this paper is to determine the mechanical behavior of PLA-parts fabricated using Open-Source 3D printer based on FDM process. The mechanical behavior is characterized by two proprieties which are flexural strength and flexural modulus of elasticity. The mechanical properties are determined from the experimental results of three-point bending test according to the following process parameters: printing speed, deposition angle and extruder temperature. The results obtained show that the mechanical properties depend on the three process parameters. The response surface method and the variance analysis technique were used to establish an empirical model between process parameters and mechanical properties. The optimal printing parameters were determined using the desirability function. The Finite Element Analysis for Flexural Strength was performed to validate the experimental results.

International Journal for Simulation and Multidisciplinary Design Optimization

Fused deposition modeling (FDM) is one of the most used additive manufacturing processes in the c... more Fused deposition modeling (FDM) is one of the most used additive manufacturing processes in the current time. Predicting the impact of different 3D printing parameters on the quality of printed parts is one of the critical challenges facing researchers. The present paper aims to examine the effect of three FDM process parameters, namely deposition velocity, extrusion temperature, and raster orientation on the bending strength, stiffness, and deflection at break of polylactic acid (PLA) parts using Taguchi design of experiment technique. The results indicate that the temperature has the highest impact on the mechanical properties of PLA specimens followed by the velocity and the orientation. The optimum composition offering the best mechanical behavior was determined. The optimal predicted response was 159.78 N, 39.92 N/mm, and 12.55 mm for the bending strength, bending stiffness, and deflection at break, respectively. The R2 obtained from analysis of variance (ANOVA) showed good agr...

Engineering Computations

Purpose The purpose of this paper is to investigate numerically mixed convection of Al2O3-water n... more Purpose The purpose of this paper is to investigate numerically mixed convection of Al2O3-water nanofluids flowing through a horizontal ventilated cavity heated from below by a temperature varying sinusoidally along its lower wall. The simulations focus on the effects of different key parameters, such as Reynolds number (200 ≤ Re ≤ 5,000), nanoparticles’ concentration (0 ≤ ϕ ≤ 0.1) and phase shift of the heating temperature (0 ≤ γ ≤ π), on flow and thermal patterns and heat transfer performances. Design/methodology/approach The Navier–Stokes equations describing the nanofluid flow were discretized using a finite difference technique. The vorticity and energy equations were solved by the alternating direction implicit method. Values of the stream function were obtained by using the point successive over-relaxation method. Findings The simulations were performed for two modes of imposed external flow (injection and suction). The main findings are that the dynamical and thermal fields ...

Heat Transfer Engineering

ABSTRACT The problem of mixed convection heat transfer inside a horizontal vented enclosure throu... more ABSTRACT The problem of mixed convection heat transfer inside a horizontal vented enclosure through the lower and upper parts, respectively, of its left and right vertical walls is studied numerically using Al2O3-water nanofluid as working fluid. The bottom wall is subjected to a linearly varying (increasing or decreasing) heating temperature profiles, while the other boundaries are considered thermally insulated. The fresh fluid is admitted from the bottom part of the left vertical wall by injection or by the suction imposed on the opening of the right vertical wall. Based on numerical predictions, the conjugate effect of the Reynolds number and the nanoparticle concentration on fluid flow and heat transfer characteristics is studied. The obtained results demonstrate clearly the positive role of the nanoparticles addition on the improvement of the heat transfer rate and the mean temperature within the cavity. In addition, the flow structure and the temperature distribution inside the cavity are seen to be very sensitive to the variations of the Reynolds number, the imposed external flow mode, and the heating type. Results presented show that, in general, the decreasing heating mode is more favorable to the heat transfer in comparison with the case of the increasing heating mode. The cooling efficiency is found to be more pronounced by the injection/suction mode by applying the increasing/decreasing heating type.

Journal of Applied Fluid Mechanics

In this paper, a numerical investigation is carried out on mixed convection in a vertical vented ... more In this paper, a numerical investigation is carried out on mixed convection in a vertical vented rectangular enclosure filled with Al2O3-water nanofluid. The mixed convection effect is attained by heating the right wall by a constant hot temperature and cooling the cavity by an injected or sucked imposed flow. The effects of some pertinent parameters such as the Reynolds number, 100  Re  5000, the solid volume fraction of the nanoparticles, 0    0.1, and the aspect ratio of the cavity, 1  A  4, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes. For a value of the aspect ratio A = 2, the obtained results demonstrate that the increase of volume fraction of nanoparticles contributes to an enhancement of the heat transfer and to an increase of the mean temperature within the cavity. Also, it was revealed that the fluid suction mode yields the best heat transfer performance. In the case when A is varied from 1 to 4, it was obtained that the heat transfer enhancement, using nanofluids, is more pronounced at shallow enclosures than at tall ones.

The present work reports numerical results of mixed convection and surface radiation within a hor... more The present work reports numerical results of mixed convection and surface radiation within a horizontal ventilated cavity, with an aspect ratio A = L′/H′ = 2, heated from below and provided with an adiabatic partition, of a fine thickness, on the heated surface. Air, a radiatively transparent medium, is considered to be the cooling fluid. The effect of the governing parameters, which are the Reynolds number, 200 ≤ Re ≤ 5000, the partition position from the inlet, 0.25 ≤ L b ≤ 1.75, and the emissivity of the walls, 0 ≤ ε ≤ 0.85, on the fluid flow and heat transfer characteristics is studied in detail. The relative height of the partition, H b = H′ b /H′, and the relative height of the openings, B = h′/H′, are kept constant at 1/2 and 1/4 respectively.

In this paper is reported an analytical and numerical study on double-diffusive natural convectio... more In this paper is reported an analytical and numerical study on double-diffusive natural convection in a non-Newtonian power-law fluid confined in a shallow horizontal rectangular enclosure submitted to uniform heat and mass fluxes along its short vertical sides, while the horizontal ones are insulated and impermeable. Here, the cases of aiding and opposing thermal and solutal buoyancy forces of equal intensities are considered. In the first part of the work the fullgoverning equations are solved and the effects of the power-law behavior index, n, and the generalized thermal Rayleigh number, RaT , are examined and analyzed. In the second part, an analytical solution, based on the parallel flow approximation valid in the case of a shallow cavity, is proposed and an excellent agreement of results between the two approaches is observed, which validates them mutually.

International Symposium on Advances in Computational Heat Transfer, 2008

Numerical Heat Transfer, Part A: Applications, 2007

ABSTRACT The effect of gray surfaces' radiation on mixed convection in a horizontal chann... more ABSTRACT The effect of gray surfaces' radiation on mixed convection in a horizontal channel with finite length (aspect ratio A r = L′/H′ = 10) is investigated numerically. The cooling fluid (air, Pr = 0.72) is considered transparent to radiation. The channel is heated discretely from below and insulated from above. Flow patterns, temperature distribution, convective Nusselt number, radiative Nusselt number, and total Nusselt number are presented for different combinations of the governing parameters, which are the surface emissivity ( 0 ≤ ε ≤ 1 ), the Reynolds number (3 ≤ Re ≤ 1,000) and the Rayleigh number (104 ≤ Ra ≤ 8 × 105). The results obtained show the existence of two flow regimes controlled by the governing parameters. The multiplicity of solutions is obtained for low values of Re in a limited range of ε.

Numerical Heat Transfer Part A-applications, 2007

A numerical study is carried out to investigate the interaction between natural convection and th... more A numerical study is carried out to investigate the interaction between natural convection and thermal radiation in a horizontal enclosure filled with air and heated discretely from below. The results are presented for a cavity having an aspect ratio Ar = L′/H′ = 10, while the Rayleigh number and the emissivity of the walls are varied in the ranges 10 ≤ Ra ≤ 10 and 0 ≤ ϵ ≤ 1, respectively. The

International Journal of Heat and Fluid Flow, 2008

Heat and Mass Transfer, 2005

Energy Conversion and Management, 2009

The present paper reports numerical results of mixed convection and surface radiation within a ho... more The present paper reports numerical results of mixed convection and surface radiation within a horizontal ventilated cavity heated from below and provided with an adiabatic thin partition on the heated surface. Air, a radiatively transparent medium, is considered to be the cooling fluid. The effect of the governing parameters, which are the Reynolds number, 200 6 Re 6 5000, the baffle position from the inlet, 0.25 6 L b 6 1.75, and the emissivity of the walls, 0 6 e 6 0.85, on the fluid flow and heat transfer characteristics is studied in detail. The maximum and mean temperatures, the ratio, Q E /Q L , of the heat quantities leaving the cavity through the exit, Q E , and through the vertical cold left side, Q L, are also presented versus the above controlling parameters.

Energy Conversion and Management, 2008

This paper reports an analytical and numerical study of double-diffusive natural convection in a ... more This paper reports an analytical and numerical study of double-diffusive natural convection in a non-Newtonian power-law fluid contained in a horizontal rectangular enclosure submitted to uniform heat and mass fluxes along its short vertical sides, while the horizontal ones are insulated and impermeable. The first part from this study is devoted to the numerical solution of the governing equations, and the effect of the governing parameters, namely, the cavity aspect ratio, A, the Lewis number, Le, the buoyancy ratio, N, the power-law behavior index, n, and the generalized Prandtl, Pr, thermal Rayleigh, Ra T , numbers, is examined. In the second part, an analytical solution, based on the parallel flow approximation in the case of a shallow cavity (A) 1), is proposed and a good agreement is found between the two types of solutions.

Computational Thermal Sciences, 2014

ABSTRACT In this paper, we examine mixed convection in a horizontal ventilated enclosure filled w... more ABSTRACT In this paper, we examine mixed convection in a horizontal ventilated enclosure filled with water–Al2O3 nanofluid. The mixed convection effect is attained by heating the bottom wall at a constant hot temperature and cooling the cavity through an injected or sucked imposed flow. The flow enters the enclosure through an opening located in the lower part of the left vertical wall and leaves from the upper part of the right vertical wall. The remaining boundaries are considered adiabatic. The effects of some pertinent parameters such as the Reynolds number, 200 <=� Re �<= 5000, and the solid volume fraction of the nanoparticles, 0<= � ϕ � <=0.1, on flow and thermal fields and the resulting heat transfer are examined for the two ventilation modes (injection and suction). The obtained results show that the presence of nanoparticles contributes to enhancement of the heat transfer and an increase in the mean temperature within the cavity. In addition, the Reynolds number and the mode of imposed external flow affect the dynamical and thermal flow structures. Also, it was found that the fluid suction mode favors the heat transfer in comparison with the case of the fluid injection mode.