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The purpose of this paper is to study numerically thermosolutal natural convection within an inclined rectangular cavity in the presence of Soret effect and heat generation. The enclosure is heated and salted from its long sides with constant but different temperatures and concentrations. The study focuses on the effects of three main parameters which are, the Soret parameter (Sr = 0 and –0.5), the internal to external Rayleigh numbers ratio 0 ≤ R ≤ 80 and the cavity inclination γ, varied from 0° (vertical position) to 60°. The combined effects of these parameters on fluid flow and heat and mass transfer characteristics are examined for the external Rayleigh number Ra_E = 10⁵, the Prandtl number Pr = 0.71, the buoyancy ratio N = 1, the Lewis number Le = 2 and the aspect ratio of the cavity A = 2.

A hybrid lattice Boltzmann-finite difference method (LBM-FD) was used to tackle the problem under consideration. The LBM with the simple relaxation time was used for the fluid flow in the presence of the gravity force, while the temperature and concentration equations were solved separately using an explicit finite-difference technique at the Boltzmann scale.

The monocellular nature of the flow, obtained for R = 0 is not destroyed by varying the cavity inclination and the Soret parameter but rather by the increase of the parameter R. The Soret parameter and the cavity inclination become perceptible at high values of R. The inclination γ = 60° leads to high mean temperatures compared to the other inclinations. The effect of R on mean concentration is amplified in the presence of Soret effect but limited in the absence of the latter. The negative Soret parameter combined with high internal heat generation and a relatively high inclination is important when the objective is to maintain the fluid at a high concentration of species. The presence of bicellular flow combined with the important elevation undergone by the fluid temperature, makes both the cold and hot walls playing a cooling role with the most important exchanges taking place at the upper part of these walls. The analysis of the mean mass transfer shows that the increase of the inclination may lead to an increase or a decrease of the mass transfer depending on the range of R, in the case of Sr = 0. However, for Sr = −0.5, it is observed that the increase of γ is generally accompanied by a reduction of the mass transfer.

To the best of the authors’ knowledge, the hybrid LBM-FD was not used before to study such a problem. Combined effect of R and inclination may be useful in charging the fluid with species when the objective is to maintain high concentrations in the medium.

The purpose of this paper is to study analytically and numerically the Soret effect on double diffusive natural convection induced in a horizontal Darcy porous layer subject to lateral heat and mass fluxes. The work focuses on the particular situation where the solutal to thermal buoyancy forces ratio, N, is related to the Soret parameter, S_P, by the relation. For this particular situation, the rest state is a solution of the problem. The analytical identification of the parallel flow bifurcations counts among the objectives of the study. The effect of the governing parameters on the fluid flow properties and heat and mass transfer characteristics is also examined.

Both the Darcy model and the Boussinesq approximation are used for the mathematical formulation of the problem. The geometry under study is a horizontal porous cavity filled with a binary fluid. The problem is solved analytically on the basis of the parallel flow approximation, valid in the case of a shallow cavity. The analytical results are validated numerically using a second‐order finite difference method.

The main finding is the absence of a supercritical bifurcation for this problem. More precisely, in the studied case, only the subcritical convection was found possible for the parallel flow structure and its threshold was determined analytically versus the governing parameters. It is also shown that the S_P‐Le plane can be divided into two parallel flow regions; in one region the flow is counterclockwise while it is clockwise in the other. At sufficiently large values of R_T, two solutions of ψ0, termed as “stable” and “unstable” and varying, respectively, as R_T^1/3 and R_T⁻¹ were obtained. The flows corresponding to these solutions are rotating in the same direction with different intensities. An analytical expression is established for the critical Rayleigh number which allows a control of the onset of motion in the system.

The thermodiffusion phenomenon in saturated porous geometries is of practical interest in several natural and technological processes such as the migration of moisture through air contained in fibrous insulations, food processing, contaminant transport in ground water, electrochemical processes, etc.

The study concerns the Soret effect within a system subject to outside mass flux. Only one type of bifurcation (subcritical bifurcation) was found possible for the parallel flow structure in the present configuration instead of two kinds of bifurcations (supercritical and subcritical).

Thermodiffusion or Soret effect is a phenomenon that can be encountered in many applications. However only little is known about this phenomenon, particularly in the case of sparsely packed media (i.e. Brinkman media). The aim of this paper is to study numerically and analytically the effect of thermodiffusion on the onset of natural convection in a horizontal Brinkman porous layer with a free‐stress upper boundary.

The study is performed by solving numerically the governing equations for different combinations of the governing parameters. An analytical solution is also developed in the case of a shallow layer using the approximation of a parallel flow in the core region to predict the critical conditions corresponding to the onset stationary, subcritical and Hopf convection.

The results obtained show that, in the presence of Soret effect, the numerical and analytical solutions agree well for long enough layers. The thermodiffusion parameter can affect considerably the supercritical and sub‐critical Rayleigh numbers and heat and mass transfer characteristics in the layer. It is also shown that the plane Le‐φ can be divided into three main regions with specific and different behaviours.

The Soret effect can play a stabilizing or a destabilizing role and this, depending on the sign of the separation parameter, φ.

The purpose of this paper is to study analytically and numerically the effect of a transverse magnetic field on the separation of species induced in an inclined rectangular porous cavity saturated with an electrically conducting mixture.

The porous layer is assumed homogeneous and submitted from its long sides to uniform heat fluxes and to a magnetic field of strength B. The Darcy model combined with the Boussinesq approximation are used to study the heat and solute transfer in the medium. An analytical solution is developed on the basis of the parallel flow approximation. Numerical simulations are also performed in order to validate the analytical solution. The controlling parameters of this problem are the thermal Rayleigh number, the inclination of the enclosure, the separation parameter, the Hartmann number and the Lewis number.

For given values of the thermal Rayleigh number, the inclination of the enclosure, the separation parameter and the Lewis number, there is an optimal magnetic field which leads to a maximum of separation. At relatively high Rayleigh numbers, where convection destroys the separation process, it is possible, with an optimal choice of the Hartman number, to recover a good level of separation.

Since the problem is governed by several parameters (five parameters), only the Darcy model was used in this study instead of the Darcy-Brinkman extended model even if the latter model allows to cover the pure fluid and Darcy porous media as limiting cases.

In separation experiments, it is very difficult technically to work with small Rayleigh numbers due to technical difficulties. However, the process of separations is canceled at high Rayleigh number by the strength of convection which causes a mixing in the binary mixture. This study shows that, by using adequate combinations of the controlling parameters, it becomes possible to reach a good level of separation even at relatively high Rayleigh numbers.

Optimum choice of the magnetic field and the inclination of the cavity may lead to a good level of the separation process. For large Lewis numbers, the separation vanishes far above and far below the optimal Ha. However, for small Lewis numbers, an important level of separation is maintained for any Ha located below the optimal value of the latter parameter.

The purpose of this paper is to present a numerical and an analytical study of the thermohaline convection with Soret effect in a square enclosure filled with a binary fluid mixture.

The horizontal boundaries of the enclosure are impermeable and heated from below while its vertical walls are assumed to be adiabatic and impermeable. The Navier‐Stokes equations under the Boussinesq‐Oberbeck approximation are solved numerically. The results are given for different values of the separation ratio. The critical Rayleigh number at the onset of convection is determined analytically and numerically. The Hopf frequency at the onset of convection is obtained.

The existence of two stable stationary bifurcation branches is illustrated. Furthermore, it is shown that the existence of stable traveling waves in the transition from one branch to the other depends on the value of the separation ratio. For some values of Rayleigh number, asymmetric flows are observed. A good agreement is found between the numerical solution and analytical analysis.

The present work is the first to consider thermosolutal convection with Soret effect in a square enclosure.

This study aims to investigate experimentally and numerically the thermal analysis of a wavy diverging-converging corrugated enclosure, partitioned into two parts under the effect of magnetohydrodynamic (MHD) natural convection. The left part was filled with Al₂O₃/C₂H₆O₂ nanofluid, while the right part was Al₂O₃/C₂H₆O₂ saturated by a porous medium, featuring a corrugated cylinder at the center. This system is relevant to many engineering applications. Key factors affecting thermal performance, such as nanofluid volume fraction, Darcy number, Hartmann number, inclination angle of MHD and Rayleigh number, were analyzed. This study evaluated the impact of these parameters on stream function, average Nusselt number and isothermal lines under three heat source scenarios: heating the corrugated cylinder, heating the magnetic source and heating the nanofluid, porous media and corrugated walls.

The main governing equations for the nanofluid flow are mass, momentum and heat transfer, while the porous media are modeled using the Darcy–Brinkmann model. These governing equations are transformed into a dimensionless form and solved numerically using COMSOL 6.0 based on the finite-element method. Dynamic viscosity, density and thermal conductivity equations are used to calculate the properties of the nanofluid at different volume concentrations.

The results showed that increasing the Rayleigh number (Ra) and Darcy number (Da) increased the Nusselt number by 55%, indicating enhanced heat transfer. A vertical magnetic source (γ = 90°) further improved thermal performance. Conversely, thermal performance decreased with increasing Hartmann number (Ha). The highest Nusselt number was observed when the heat source was applied to the corrugated cylinder, followed by the right side with nanofluid–porous contact and was lowest for the left side with nanofluid contact. Experimental data demonstrated that the presence of a magnetic field can significantly increase the temperature, thereby enhancing heat transfer by natural convection, particularly when the heat source is applied in the region of nanofluid–porous contact.

The primary originality of this work lies in the use of a novel design featuring a diverging-converging structure with a wavy wall. In addition, it uses two types of fluids simultaneously, dividing the enclosure into two sections: the right side contains nanofluid mixed with a porous medium, while the left side is filled with nanofluid only. The system also includes a corrugated cylinder at its center with four undulations. The position of the heat source significantly influences heat dissipation. Therefore, three different positions were examined: heating the cylinder at a constant temperature, heating the left side of the enclosure and heating the right side.

This paper aims to investigate the onset of convection, heat and mass transports in a sparse porous layer saturated with chemically reactive binary fluid mixture heated and salted from below under the influence of Soret and Dufour effects.

The Brinkman model is used for momentum equation. Linear stability analysis based on normal mode technique is used to evaluate the onset threshold for stationary and oscillatory convection. In weak-nonlinear theory, the truncated Fourier series method is used. The resulting system of differential equations is solved numerically by using the Runge–Kutta fourth-order method.

Because of the competition between the processes of thermal, solute diffusions, chemical reaction and cross-diffusions, the onset of instability is via oscillatory mode instead of stationary. The effect of dissolution/precipitation of reactive component and the cross-diffusions on the stability, heat and mass transports is investigated.

By the proper adjustment of underlying parameters, the onset of convection can either be advanced or delayed as per the requirement. Therefore, the present investigation forms a useful tool for regulating the onset of convection.

This work evaluates the risk of wastewater in transmitting intestinal helminths to a population living near an urban effluent.

This study is a copro‐epidemiological evaluation of the school‐age children of Sidi Daoui, a neighbourhood in the discharge area of the main sewer of the city of El Jadida and a control group from Sidi Moussa, a district far from the discharge area.

Intestinal helminths are more prevalent among the children of the study group of Sidi Daoui by 43 percent, compared with 20 percent in the control group, mainly caused by ascariasis and hymenolepiasis. Enterobiasis is an intestinal vermin present with similar expansion in both zones. Polyparasitism, which cannot be found in the control group, is 6 percent in the discharge area. A total of 22 percent of helminthiasis cases among these children are attributed to wastewater, in particular ascariasis (17 percent) and hymenolepiasis (11 percent). It was found that boys are the most vulnerable, mostly between the ages of seven to nine.

Provides some useful information concerning the risk of wastewater transmitting intestinal helminths.

The purpose of this study is to numerically analyze the thermal and entropy generation characteristics on two-dimensional, incompressible, laminar single-phase flow of Al₂O₃-water nanofluid in a micro-channel subjected to asymmetric sinusoidal wall heating with varying amplitude, length of fluctuation period and phase difference of applied heat flux for Reynolds number in the range of 25-1000.

The numerical computation is based on the Finite Element Method and the Lagrange finite element technique is used for approximating the flow variables within the computational domain.

The average Nusselt number increases with increasing Reynolds number (Re) for all the volume fractions of nanofluid. However, the total entropy generation decreases up to a critical value of Re and increases thereafter. Increase in volume fraction shifts the critical Re towards the lower Re regime. The average Nusselt number and total entropy generation increase with amplitude and length of fluctuation period of heat flux. The optimal choice of volume fraction for lesser entropy generation and higher heat transfer is found to be 3 per cent independent of the value of amplitude, length of fluctuation period and phase difference of the heat flux.

To the best of authors’ knowledge, the interplay of various parameters concerning non-uniform heating in achieving the maximum heat transfer with minimum irreversibility has not been investigated. Focusing on this agenda, the results of this study would benefit the industrial sector in achieving the maximum heat transfer at the cost of minimum irreversibilities with an optimal choice of inlet Reynolds number, volume fraction of nanofluid, amplitude, length of the period of fluctuation of heat flux and phase difference of applied heat flux.

The heat transfer rates from the body to the working fluid can be improved through altering geometric configurations of the body and its arrangement in the flow system. One of the arrangements for this purpose is to locate the body at the channel inlet while the convection current opposes it. Since the flow field in the channel inlet influences the heat transfer rates, changing the aspect ratio and inclination of the body is expected to modify the flow field while enhancing the heat transfer rates. Consequently, investigation into the influence of the aspect ratios and tilting angles of the body on the heat transfer rates in the channel flow becomes essential. The paper aims to discuss these issues.

Numerical simulation of flow in a channel with the presence of solid block is carried out. The block aspect ratio is changed while keeping the area of the block constant for all aspect ratios. The tilting angle is also incorporated analysis to examine its effect on the Nusselt number.

The throttling effect of the block at channel inlet accelerates the flow between the channel wall and the block faces. This, in turn modifies the thermal boundary layer around the block. In this case, heat transfer rates increase considerably at the block faces where the flow acceleration suppresses the thermal boundary layer thickness. This is more pronounced for large block tilting angles. The Nusselt number attains low values for the block face opposing to the flow at the channel inlet and the back face of the block. This is attributed to the mixing of the thermal current emanating from the side faces of the block in the region close to the back surface. In this case, thermal boundary layer thickens and the heat transfer rates from the block reduce significantly. The Nusselt number improves with reducing the block aspect ratio, which is particularly true along the side faces of the block. In addition, the influence of the block tilting angle on the Nusselt number is considerable for the low block aspect ratios.

The model study is validated with the previous studies for the drag coefficient. The study covers all the aspects of the flow situations and discusses the resulting fluid field and the heat transfer rates from the block.

It is an interesting work for cooling applications. The block aspect ratio and its tilting angle in the channel influence considerably the flow field and the Nusselt number variation around the block faces.

The cooling technology may be improved through implementing the findings of the current work.

It is an original work and it has never been submitted to other journals.