Simulation of air flow distribution in rooms by a systemic approach.

In order to achieve a satisfactory level of hygiene and comfort in premises and to assess the pollutant transfers, it is necessary to control the air flow distribution. An intermediate approach between predictive numerical simulation and experimental determination of aerodynamic parameters characterizing air distribution in rooms, is the systemic approach. The paper presents the principles of this approach which is based on the residence times distribution (RTD) theory, commonly used in chemical engineering. The aim of the IDTS code recently developed is to build a model from a combination of elementary systems representing basic ideal flows (mixing flow, piston, ... ). The adjustment of this model is derived from the comparison of the response to a signal injected into the model with an experimental tracer emission realized in the ventilated room inlet. The general strategy adopted, consisting of a decoupled treatment of parametric identification of structural model determination, is presented. The comparison between experimental residence times distribution on a ventilated laboratory enclosure and the simulated one shows good agreement, as well as the comparison performed with results from a Computational Fluid Dynamics (CFD) tool.