Samir Yahiaoui

@article{maiti_3237,

title = {A Reduced Model Retaining 1st-Order Vortex Corrections in the Averaged Dynamics of the Wind past Buildings},

author = {Samik Maiti and Aminallah Rabia and Amine Ammar and Alessandro Biancalani and Francisco Chinesta and Yannick Hoarau and Samir Yahiaoui},

url = {https://doi.org/10.18280/ijht.420506},

year  = {2024},

date = {2024-10-01},

journal = {International Journal of Heat and Technology},

volume = {42},

number = {5},

pages = {1534},

abstract = {The nonlinear dynamics of turbulence formed by the wind flowing near solid objects can

be studied with a variety of different physical models, more or less numerically demanding.

An application is the study of the formation of turbulence past buildings, with the goal of

determining the no-fly zones for drones in smart cities. In this paper, we examine the

Reynolds- averaged Navier-Stokes (RANS) model, which is popular in simulating the wind

dynamics in small portions of a city. We compare the results with those of the Large-Eddy-

Simulation (LES) model, more physically comprehensive, but more numerically

demanding. The analysis of the vortex formation in the LES model helps estimating the

1st-order correction to add to the lighter RANS results. This constitutes the scheme of a

reduced model, which takes the RANS model as a basis, on top of which an extra layer of

the dimension of the main vortex, obtained with the LES simulation, is added. This reduce

model can be used, for example, to estimate the no-fly zone with a higher level of accuracy

with respect to the pure RANS, yet with a computational effort comparable to the pure

RANS.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{agaciak_628,

title = {Dehydration and drying poly(vinyl)chloride (PVC) porous grains: 2. Thermogravimetric analysis and numerical simulations},

author = {Philippe Agaciak and Samir Yahiaoui and Madeleine Djabourov and Thierry Lasuye},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0927775715000394?via%3Dihub},

year  = {2015},

date = {2015-01-01},

journal = {Colloids And Surfaces A-Physicochemical And Engineering Aspects},

volume = {470},

pages = {120-129},

abstract = {This paper analyzes the drying rates of humid porous grains of poly(vinyl)chloride PVC by thermogravimetry. Grains have variable volume fractions of pores, representing between 16 and 33%g water/g PVC, with pore sizes varying between 0.6 and 1?m. It is shown that the humid cakes exhibit three different drying rate regimes at constant temperature, characterizing evaporation of free water, of interstitial water and of water inside the pores. The constant rate period (CRP) and the falling rate period (FRP) of drying are clearly identified. The drying rates and drying times are presented in adimensional units by comparison with evaporation of pure water. The thermogravimetric analysis identifies a fraction of water which dries very slowly inside the pores. A method of quantifying the strongly bound water is presented. Numerical simulations of water evaporation were performed on a 2D array of channels and illustrate the contribution of geometrical effects (diameter of channels, tortuosity, etc.) in pore drying. Visual observations of the drying of droplets of solutions containing dispersants used in PVC synthesis show interesting patterns. The phase separated solutions of dispersants are analyzed and their role in drying is highlighted.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{agaciak_629,

title = {Dehydration and drying poly(vinyl)chloride (PVC) porous grains: 1. Centrifugation and drying in controlled humid atmospheres},

author = {Philippe Agaciak and Samir Yahiaoui and Madeleine Djabourov and Thierry Lasuye},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0927775715000308?via%3Dihub},

year  = {2015},

date = {2015-01-01},

journal = {Colloids And Surfaces A-Physicochemical And Engineering Aspects},

volume = {469},

pages = {132-140},

abstract = {Concentration of aqueous suspensions of solid particles (called slurries in industrial processes) is achieved by centrifugation at high accelerations and it is an important step in dry powder productions; dehydration precedes drying. In aqueous suspensions of porous particles, water is both the interstitial fluid, which disperses the particles and the imbibition fluid, which fills the pores inside particles. This is the case in the pastes of poly(vinyl)chloride (PVC) polymerized in suspensions after centrifugation. PVC grains are non-colloidal particles with diameters close to 150?m and variable inner porosity, which are synthetized in aqueous solutions using dispersants such as various poly(vinyl)alcohols (PVA). In this paper we determine the dehydration by centrifugation of different grades PVC suspensions with laboratory scale experiments. It is shown that the humid pastes reach a pendular state at high accelerations and that the compaction of the grains and their surface properties determine the final retention of the water by capillary forces. In such conditions, internal water, inside the pores of the grains can be eliminated only by evaporation. Drying was investigated in controlled relative humidity atmospheres (RH) in desiccators by measuring the equilibrium moisture content of the grains and the evaporation rates. The evaporation rate of the superficial water is similar to pure water and can be interpreted using Stefan's equation, whereas substantial differences exist between the total drying times of grades.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}