Zohir Younsi

Understanding the Dynamic and Static Thermal Transfer in Brick Walls

The aim of this paper is to study the thermal heat transfer through a 33 cm brick wall, typical of old houses in Lille, a northern French town. First, the wall was studied in a steady state case in order to determine its equivalent resistance using the electrical analogy. Then, the wall is replaced by an equivalent homogeneous wall in order to compare the 1D and the 3D thermal transfer. The results show a perfect consistency between the two models, representing a big advantage when other layers are added to the model like thermal insulation and facing.

Computational of the wind velocity effect on infiltration rates in an individual building using multi-zone airflow model

ABSTRACT This paper presents and discusses numerical simulation of the wind velocitys effect on infiltration rates in an individual building using multi-zone modelling. The governing equations are expressed in terms of unknown pressures at points where flow paths connect. Their implementation was achieved using an advanced numerical model, which was developed via the MATLAB environment. Such a numerical approach has been validated through available results. A good agreement has been observed between available data and our studys results. Moreover, the model implemented allows to determine the reference pressure in each zone to compute the air infiltration rate by each connection. To perform this, a large range of input data is needed. These include leakage characteristics of airflow elements, wind pressure coefficients, and ventilation system characteristics. To sum up, it is found that the wind velocity increase produces a strongly variation on computed infiltration rates.

Double-Diffusive Natural Convection in a Mixture-Filled Cavity with Walls' Opposite Temperatures and Concentrations

ABSTRACT This paper deals with natural convection flows evolving inside an ended and differentially heated cavity, which is filled either with an air or an air–CO2 mixture. The investigation was conducted through the laminar regime to analyze buoyancy ratio changes effect on heat and mass transfers both in aiding and opposing flows. The thermal Rayleigh number was varied from 103 to 107. Streamlines, isotherms, iso-concentrations, and local and average Nusselt and Sherwood numbers are provided to demonstrate the convective flow induced. The governing equations are solved by finite volume method using SIMPLEC algorithm to handle the pressure–velocity coupling. The buoyancy ratio effect on dynamic, thermal, and mass fields is noteworthy, exhibiting both the competition between thermosolutal forces and fields stratification. From the results, it turned out that, in general, when the buoyancy ratio is: (1) positive, thermosolutal buoyancy forces are cooperative, (2) nil, solutal buoyancy forces are weak and the flow is merely thermoconvective, (3) negative and greater than −1, buoyancy effects are competing and thermal convection dominates, (4) −1, buoyancy effects are canceled and heat and mass transfers are driven only by diffusion, and (5) less than −1, buoyancy forces compete with a dominant solutal convection.