Talib Dbouk

University of Rouen Normandy · CORIA Lab.

The present work is based on the Finite Element Method as the discretization technique coupled to a density approach, an alternative interpolation function in this paper. A new dimensionless objective function combining minimum energy consumption and maximum thermal performance of topology optimization is proposed, and the performance of the approa...

The design of rigid vortex generators (RVG) influences the thermal performance of various technologies. We employed Discrete Adjoint-Based Optimization to show the optimal development of vortex generators. Under turbulent flow conditions, different bi-objective functions on the RVG design were examined. Specifically, we aimed at an optimal RVG shap...

This paper concerns technology challenges for the wind and solar sectors and the role of computational science in addressing the above. Wind energy challenges include understanding the atmospheric flow physics, complex wakes and their interaction with wind turbines, aeroelastic effects and the associated impact on materials, and optimisation of win...

According to WHO, by 2050, at least one person out of two will suffer from an allergy disorder resulting from the accelerating air pollution associated with toxic gas emissions and climate change. Airborne pollen, and associated allergies, are major public health topics during the pollination season, and their effects are further strengthened due t...

Aerosol pollutant particles indoors significantly affect public health. The conventional wisdom is that natural ventilation will alleviate the dispersion of airborne or aerosol particles. However, we show that the problem is far more complex and that natural ventilation should be applied under specific conditions to be effective. We performed sever...

Multifunctional heat exchangers (HEX) are very important devices which are used in many industrial applications (aerospace, aeronautics, automobile, process and chemical engineering, etc). Improving their designs for an optimal overall performance is still a wide window for both research and development. In the present contribution, a new HEX desig...

In this paper, the corrected thermodynamic model of the heat exchanger is proposed, the application of the Entransy Loss Theory in the helically coiled tube heat exchanger is modified, three modeling methods are proposed and selected, Entransy Loss Number (NgHE) combining with Performance Evaluation Criteria (PEC) and Field Synergy Number (Fc) as t...

Multicopter drones have a complex geometry involving several rotors. Therefore, computational resources could hinder their aeroacoustics modelling and simulation. Furthermore, such simulations require solving the aerodynamics at different scales (propellers and fuselage) and the sound spectrum for observers away from the drone. This paper presents...

This study presents a computational fluid dynamics, susceptible–infected–recovered-based epidemic model that relates weather conditions to airborne virus transmission dynamics. The model considers the relationship between weather seasonality, airborne virus transmission, and pandemic outbreaks. We examine multiple scenarios of the COVID-19 fifth wa...

Air purifiers are limited to small polluting airborne particles and poor air circulation (fan) for bringing airborne particles inside the device. Thus, the optimal utility of domestic air purifiers (DAPs) for eliminating airborne viruses is still ambiguous. This paper addresses the above limitations using computational fluid dynamics modeling and s...

Endotracheal tubes (ETT) passed inside the human trachea witness tube bending at different angles, affecting the ocal fluid flow dynamics. This induces a variable mechanical ventilation performance across patients’ comfortability evels. Our understanding of the ocal fluid flow dynamics phenomena is thus crucial to enhance the maneuverability of ETT...

Aim Cardiopulmonary resuscitation (CPR) is an emergency procedure where interpersonal distance cannot be maintained. There are and will always be outbreaks of infection from airborne diseases. Our objective was to assess the potential risk of airborne virus transmission during CPR in open-air conditions. Methods We performed advanced high-fidelity...

It is well established that the data reported for the daily number of infected cases during the first wave of the COVID-19 pandemic were inaccurate, primarily due to insufficient tracing across the populations. Due to the uncertainty of the first wave data mixed with the second wave data, the general conclusions drawn could be misleading. We presen...

This study investigates how airborne pollen pellets (or grains) can cause severe respiratory-related problems in humans. Given that pollen pellets can capture ribonucleic acid viruses, we show that airborne pollen grains could transport airborne virus particles such as the airborne coronavirus (CoV) disease (COVID-19) or others. We consider the env...

Swarms of drones is an emerging field of research and technology. Multicopter drones are noisy machines, and the noise effects would increase for a swarm. It is, therefore, essential to understand what flight formation conditions would reduce noise emissions. This study concerns the noise induced by drone swarms. We developed a high-resolution comp...

Epidemic models do not account for the effects of climate conditions on the transmission dynamics of viruses. This study presents the vital relationship between weather seasonality, airborne virus transmission and pandemic outbreaks over a whole year. Using data obtained from high-fidelity multi-phase, fluid dynamics simulations, we calculate the c...

The impact of air ventilation systems on airborne virus transmission (AVT), and aerosols in general, in confined spaces, is not yet understood. The recent pandemic has made it crucial to understand the limitations of ventilation systems regarding AVT. We consider an elevator as a prototypical example of a confined space and show how ventilation des...

For the first time, Eulerian three-dimensional transient modeling of thermal convection in immersed granular beds (IGB) has been developed. The modeling accounts for the destabilization of the IGB and the granular boundary upper layer deformation induced by thermal heating element. As observed in the recent experiments, the developed 3D CFD model p...

The contribution of this paper toward understanding of airborne coronavirus survival is twofold: We develop new theoretical correlations for the unsteady evaporation of coronavirus (CoV) contaminated saliva droplets. Furthermore, we implement the new correlations in a three-dimensional multiphase Eulerian–Lagrangian computational fluid dynamics sol...

The numerical and experimental data of the helically coiled-twisted trilobal tube (HCTTT) heat exchanger are compared, the results present that, due to more intense secondary flow of the HCTTT caused by the superposition of overall twist and self-twist, region near the center of the HCTTT has higher turbulent kinetic energy, and the region near the...

Face mask filters—textile, surgical, or respiratory—are widely used in an effort to limit the spread of airborne viral infections. Our understanding of the droplet dynamics around a face mask filter, including the droplet containment and leakage from and passing through the cover, is incomplete. We present a fluid dynamics study of the transmission...

In many applications, convective heat transfer enhancement is readily achieved by generating streamwise vortices and coherent flow structures using Vortex Generators (VG's) such as in multifunctional heat exchangers/reactors. Shape optimization of the VG's have been carried out over the last decades to find enhanced designs. Meanwhile, the design v...

Our understanding of the mechanisms of airborne transmission of viruses is incomplete. This paper employs computational multiphase fluid dynamics and heat transfer to investigate transport, dispersion, and evaporation of saliva particles arising from a human cough. An ejection process of saliva droplets in air was applied to mimic the real event of...

Compared to single-liquid and liquid-liquid jets in cross flow (JICF), liquid-solid two-phase JICF is rarely studied. An experimental setup has been developed to investigate a vertical jet of liquid-solid mixture in water turbulent crossflow at Re≈ 2.2 · 10^4 over 4 seconds period. Rigid micro particles were injected vertically in a horizontal pure...

Boundary layer transition over an isolated surface roughness element is investigated by means of numerical simulation. Large Eddy Simulation (LES) flow-modeling approach is employed to study flow characteristics and transition phenomenon past a roughness element immersed within an incoming developing boundary layer, at a height-based Reynolds numbe...

Le déstabilisation d’un lit granulaire immergé en mode séquentiel, induite par une source thermique locale, a été identifié pour la première fois. Au cours d'un seul mode, les comportements de déstabilisation ont été observés: déclenchement de l’instabilité, éjection de plumes, retrait des particules, resuspension et sédimentation. Un temps de dést...

A computational framework (solver) is developed for incompressible isothermal concentrated non-colloidal suspension flows of rigid particles. The number of particles can be of the order of millions. The developed solver, named “SuspensionFoam” can predict the phenomenon of shear-induced migration in complex geometries in a continuum mechanics model...

Nevertheless the huge amount of numerical and experimental works on non-colloidal suspension flows, most studies in the literature were limited to the dynamics in different geometries like in channels and pipes. To author's knowledge, mixing enhancement quantification and suspension mixing behavior in static mixers has been rarely studied before. I...

Topology optimization method is developed for a multi-objective function combining pressure drop reduction and thermal power maximization (incompressible flows at low to moderate Reynolds numbers). Innovative optimal designs are obtained, discussed and presented on a Pareto-frontier. The numerical developments (continuous adjoint technique) have be...

A new CPU cooling-fluid technology for CPU chip cooling by means of concentrated suspension flows of non-colloidal particles is introduced, and investigated through theory, complex CFD modeling and simulation. A new CPU cooling device is developed and presented in this purpose. Upon imposing a constant heat flux on one surface of the device, repres...

Modeling and simulation are developed, generalized and validated for both heat transfer and shear-induced particles migration in dense non-colloidal laminar suspension flows. Past theory and measurements for the effective thermal conductivity in porous materials at zero shear-rate are coupled to more recent effective thermal diffusivity measurement...

For optimal tree-like heat conductive structures obtained numerically by topology optimization (TO), few experimental investigations exist in the literature to author's knowledge. In this context, the present study deals with an experimental investigation of tree-like structures obtained by topology optimization (known also by bi-material volume-to...

In the present manuscript, a numerical sensitivity analysis is conducted on different physical parameters in order to assess the robustness of a 3D CFD simulation of adsorption process cycles. It is demonstrated that the effective thermal conductivity of the porous medium, the mass transfer coefficient, the column dead volumes, the equilibrium isot...

There has been a growing public health issue concerning the regulation of indoor air quality (I AQ ) and the human exposure to particulate matter (P M ). Today, this exposure is a major world wide concern because ambient P M concentrations in many cities exceeded the limits set by the European air quality directive. Underground airborne particles a...

Gas separation in packed bed of adsorbing porous medium: Modeling and Simulation

A 3D Computational Fluid Dynamics (CFD) model is developed, applied and validated for a 4-steps PSA cycle operating for separation by using Carbon Molecular Sieves (CMS). The computational results are addressed and found to be in good agreement with experimental data. The Linear Driving Force (LDF) model is employed in the present 3D CFD approach t...

Topology Optimization (TO) is a promising numerical technique for designing optimal engineering designs in many industrial applications. It is expected that it might become an unavoidable engineering tool for many new rising technologies such as the additive manufacturing or metal 3D printing as addressed recently in the literature. During the last...

M.-A. CAMPESI1, R. GAUTIER, T. DBOUK2, O. MOUSSA1, L. HAMON1, F.-X. BLANCHET1, Y. GOURIOU1, J.-L. HARION, P. PRÉ

Immersed granular flows are present widely in different domains under dif- ferent forms (at various scales) such as in nature (rivers, muds, atmosphere, blood...), and in many industrial applications (detergents, cosmetics, etc...). Studying such flows properly requires one to represent well the physics behind their dynamics: the fluid/solid intera...

This paper addresses a new suspension balance direct-forcing immersed boundary model (SB-DF-IBM), for wet granular flows over obstacles. We mean by “wet granular” term all non-Newtonian flows that are made of non-Brownian particles (rigid spheres) immersed in a Newtonian fluid. This new SB-DF-IBM couples the Suspension Balance Model (SBM) to a Dire...

A new optimization algorithm is developed in this work based on the globally convergent method of moving asymptotes (GCMMA) of (Svanberg, 1987 ; Svanberg, 2002). The new algorithm is optimized via a new internal iterative strategy, and it is then analyzed via a parametric study for the best possible performances. It serves as an important numerical...

Le papier concerne l'outil numérique parallèle développé pour l'étude des interactions entre corps rigides ou déformables. Les interactions concernent d'une part la séparation dans le cadre de la rupture dynamique de matériaux hétérogènes et d'autre part le contact entre particules en présence de fluide. La plateforme numérique associée repose sur...

To help optimize cold rolling operations, mixed lubrication models have been developed and embedded in roll bite models. The resulting models combine micro-fluidics in a porous medium (the lubricant flow between the contacting rough surfaces), microplasticity (roughness flattening / scratching), macro-plasticity (strip reduction) and roll thermo-el...

To help optimize cold rolling operations, mixed lubrication models have been developed and embedded in roll bite models. The resulting models combine micro-fluidics in a porous medium (the lubricant flow between the contacting rough surfaces), microplasticity (roughness flattening / scratching), macro-plasticity (strip reduction) and roll thermo-el...

This paper addresses the modeling of the phenomenon of particle migration in the flow of monodispersed non-colloidal suspensions at neglected inertia using the Suspension Balance Model (SBM). The SBM describes the migration flux of particles as the divergence of the particle stress tensor. It is selected in this work because of its parameters that...

This paper describes on-going efforts made to develop a fast and robust roll bite model for cold and temper rolling processes including a non-circular roll profile and a mixed lubrication model based on lubricant flow and surface asperity deformation models (only Coulomb friction is used in this paper however). First, the existing roll bite models...

We present an experimental approach used to measure both normal stress differences and the particle phase contribution to the normal stresses in suspensions of non-Brownian hard spheres. The methodology consists of measuring the radial profile of the normal stress along the velocity gradient direction in a torsional flow between two parallel discs....

This thesis deals with an experimental and numerical investigation of the phenomenon of shear-induced particle migration in inhomogeneous shear flows of mono-dispersed non-colloidal suspensions at neglected inertia. Variety of diffusion flux models that predict the shear-induced migration were presented. However, in this work, the Suspension Balan...

A 2D OpenFOAM® solver for the flows of concentrated rigid particles (a continuum approach)