Effect of Coastal Waves on Hydrodynamics in One-Inlet Coastal Nador Lagoon, Morocco

Nador lagoon is a coastal system connected to the sea through a narrow and shallow inlet; understanding its hydraulic performance is required for its design and operation. This paper investigates the hydrodynamic impacts of the whole lagoon due to tidal waves using a numerical approach. In this study we use a two-dimensional, depth-averaged hydrodynamic model based on so-called shallow water equations solved within triangular mesh by a developed efficient finite volume method. The method was calibrated and validated against observed data and applied to analyze and predict water levels, tidal currents, and wind effects within the lagoon. Two typical idealized scenarios were investigated: tide only and tide with wind forcing. The predicted sea surface elevations and current speeds have been presented during a typical tidal period and show correct physics in different scenarios

Numerical Survey of Contaminant Transport and Self-Cleansing of Water in Nador Lagoon, Morocco

Numerical simulations are presented of the flow hydrodynamics and hypothetical contaminant dispersion patterns in Nador Lagoon, a shallow lagoon with a barrier island situated on the coast of Morocco. It is found that the natural circulation forced by the tidal flow in the lagoon is greatly affected by the development of an artificial inlet in the barrier island. The case study demonstrates the potential use of modern computational hydraulics as a tool integrated in the decision support system designed to manage a lagoon ecosystem

Combined Heat and Mass Transfer of Fluid Flowing through Horizontal Channel by Turbulent Forced Convection

In the present paper, we report a numerical study of dynamic and thermal behavior of the incompressible turbulent air flow by forced convection in a two-dimensional horizontal channel. This one contains the complicated form of the deflector which has been studied by varying the inclination angle from φ = 40°, φ = 55° to φ = 65°. The baffles are mounted on lower and upper walls of the channel. The walls are maintained at a constant temperature (375 K), the inlet velocity of air is Uint = 7.8 m/s, and the Reynolds number Re = 8.73 × 104. A specifically developed numerical model was based on the finite-volume method to solve the coupled governing equations and the SIMPLE (Semi Implicit Method for Pressure Linked Equation) algorithm for the treatment of velocity-pressure coupling. For Pr = 0.71, the results obtained show that (i) the streamlines and isotherms are strongly affected by the inclinations angles at Re = 8.73 × 104, (ii) the friction coefficient near the baffles increases under the angle exchange effect, and (iii) for a constant Re, the local Nusselt number at the walls of the channel varies with increasing the inclination angle of the deflector. Furthermore, the deflectors are generally used to change the direction of the structure of flow and also to increase the turbulence levels. We can conclude that the contribution of inclined baffles improves the increase of heat and mass transfer in which the Nusselt number at a certain angle increases noticeably

Optimization of the milling process for aluminum honeycomb structures

International audienceThe milling of aluminum honeycomb structures represents today an important scientific and technical research topic for many industrial applications: aerospace, aeronautic, automotive, and naval. The difficulties encountered when milling this type of materials are linked to the small thickness of the walls constituting the honeycomb cells and the ductility of the material structure. The milling of cellular composite structures requires specific and rigorous tools. In the present work, a 3D numerical modeling of the milling process of aluminum honeycombs has been developed using Abaqus Explicit software. The effect of milling parameters, such as the spindle speed, the tilt angle, and the depth of cut, has been particularly investigated in terms of cutting forces, surface integrity, and chip morphology. To properly analyze and optimize the cutting process, experimental validation was done through milling tests with different cutting conditions. The comparison between numerical simulations and experimental tests shows that the three-dimensional model correctly reproduces the milling of this type of structure

Identification des signaux ar non-gaussiens nonstationnaires via les cumulants

Dans cet article, nous présentons une nouvelle procédure d'estimation globale des paramètres AR variables de type évolutif basée sur les cumulants. Pour évaluer ses performances, nous la testons sur un signal AR synthétique non-Gaussien dont les paramètres varient par saut en l'absence et en présence d'un bruit blanc Gaussien. En présence de bruit, la méthode que nous proposons, en utilisant un critère approprié, donne de meilleurs résultats pour la poursuite de paramètres que la méthode classique d'autocorrélation au prix d'une grande complexité de calcul

Three-dimensional analysis of a novel solar air heater conception, for an improved heat transfer and energy conversion

Solar air heating systems remain expensive, so we conducted a parametric analyzis to enhance their performance. The study focuses on a solar air heating system with a new proposed configuration including ribs with and without perforations. In the first step, we used a technique to vary the spacing (d) at 0.5, 0.3, 0.25, 0.2, 0.15, and 0.1 m for cases (1) to (6) by adjusting the number of simple inserts (type A) fixed on the absorber. In the second step, we selected the values of (d) from cases (5) and (6) that corresponded to the best thermal performance factor. We then experimented with seven types of perforated inserts: (A), (B), (C), (D), (E), (F), and (G). Our calculations focused on the Nusselt number, the friction factor, the thermal performance factor, the kinetic dissipation rate, the kinetic energy, and the turbulent viscosity. The results indicate that the presence of the inserts generates disturbances that amplify the heat exchange, thereby increasing the heat transfer rate. A rib distribution (type G) with a 0.1 m pitch (case 6) proved to be the most efficient configuration for heat transfer. At a Reynolds number of 4000, the proposed design has a Nusselt ratio of Nu/Nus = 8.5 and a friction ratio of f/fs = 4.76 compared to a smooth absorber surface. Additionally, the proposed solar air heater configuration has a thermal performance factor (η) of η = 5.32. These findings demonstrate that the proposed configuration is highly efficient and can significantly increase the heat transfer inside the absorber, thus improving the energy conversion of solar air heaters