Recent full scale experiments has detected the presence of low Reynolds number effects in the flow in a ventilated room. This means that one are unable to predict the flow patterns in some geometries for air change rates - or Reynolds numbers - which are relevant for ventilation engineering by a standard model of turbulence. In this paper it is investigated if it is possible to simulate and capture some of the low Reynolds number effects numerically using time averaged momentum equations and low Reynolds number k-e model.
The basis of this study are experimental results obtained on a real scale cell in controlled climatic conditions which are used to show the potential influence of radiative participation of inside air on natural convection in a room. In a second part, a numerical analysis of flow patterns and heat transfer in a twodimensional thermally driven cavity containing a participating fluid is presented.
Due to the limitations of computer storage and time the flow boundary conditions at an air inlet device have to be specified for numerical simulations of air flow patterns in rooms. With regard to this the present work gives velocity measurements near an industrial air inlet using a Laser-Doppler-Anemometer. From the stochastic velocity data the time-averaged velocity components, standard deviation and turbulent kinetic energy are evaluated.
Within the frame of the IEA Annex 20, laboratory and numerical experiments were conducted in order to study the flow within an isothermal parallepipedic testroom (L x W x H = 4.2 m x 3.6 m x 2.5 m). The air is injected through a complex diffuser (made of 84 nozzles) near the ceiling and is evacuated through a rectangular exit just below the inlet. While other participants to the Annex 20 made measurements on aeraulic testrooms, we used a hydraulic model scaled to the sixth. The parameters were determined according to a Reynolds similitude.
As part of the Air Infiltration and Ventilation Centre's Numerical Database development programme, Wind Pressure Coefficient data are being collected from many published sources, much of which will contribute to the Centre's ownPressure Coefficient database. To ensure the compatibility and validity of the various data sets, a preliminary comparison has been carried out of the data in use. The work has concentrated on an analysis of the effects of Cp values, for vertical walls, on calculated wind driven infiltration and ventilation rates.
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