The turbulent ventilation of a single opening enclosure

It is common practice in the study of the wind-induced ventilation of buildings to describe the mechanisms of ventilation by a non-linear oscillator equation that effectively contains two ill defined parameters - the inertial and loss coefficients. Further this equation is usually linearised by various techniques to make its use practicable. When applied to full scale or wind tunnel data there are inevitably discrepancies between the experimental and theoretical results that have, in the past, been attributed to some combination of the inadequacy of the fundamental equations (in that not all turbulent ventilation mechanisms are considered), the inaccuracy of the two coefficients (usually obtained from theoretical and steady flow analyses) or the linearisation process, This paper presents the results of a detailed investigation of this approach through a series of idealised experiments that examined the ventilation flow through an opening in a chamber in which a simulation of the internal pressure response to a sinusoidal external pressure variation was set up. It is shown that for the range of opening Reynolds numbers likely to be met in practice the theoretical/steady flow values of the inertial and loss coefficients are acceptable and that also the linearisation process is adequate. Thus any discrepancies between experimental and theoretical data should be attributed to the fact that the non-linear oscillator equation does not fully describe all the possible mechanisms of wind-induced turbulent ventilation that can exist. (C) 2000 Elsevier Science Ltd. All rights reserved.