An analytical expression for transient distribution of passive contaminant under steady flow field

Traditionally the indoor contaminant dispersion can be obtained by CFD methods. However, there is no direct relationship to quantify the transient influence of different boundary conditions including contaminant in supply air, contaminant source and initial condition on indoor contaminant distribution. To reveal such kind of influence directly, a series of transient accessibility indices are defined and a concisely analytical expression to calculate the transient contaminant distribution is then developed. The proposed expression can explicitly and quantitatively reflect the impact of supply air, contaminant source and initial condition on the contaminant distribution indoors. An experimental measurement is employed to validate the reliability of the analytical expression. It is shown that the results from the expression agree well with experimental measurement. The proposed expression may take an important role in the optimization of ventilation design and online control.