Abstract The transient development of natural displacement ventilation in a warm space with a localized source of heat is investigated theoretically to understand the fluid mechanics in detail. One of four flow modes, A, B, C and D, may develop during the transient evolution. The flow pattern of mode B, C or D can be further subdivided into two cases respectively according to a critical value of the reduced gravity of indoor original air. When the plume rises to an interface between two air layers, it may evolve to be less buoyant than that of the above layer. The subsequent flow pattern would develop in three ways, determined by whether the plume momentum and the penetrative entrainment are considered. Although the differences among the predictions corresponding to the three flow regimes are slight, the simplified model of penetration without entrainment is recommended, because it is the most reasonable and can be solved easily.

中文翻译：

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暖空间自然置换通风的理论分析

摘要 从理论上研究了具有局部热源的温暖空间中自然置换通风的瞬态发展，以详细了解流体力学。四种流动模式中的一种，A、B、C 和 D，可能会在瞬态演变过程中形成。模式B、C或D的流型可以根据室内原始空气的重力减小的临界值分别进一步细分为两种情况。当羽流上升到两个空气层之间的界面时，它的浮力可能会比上层的浮力小。随后的流动模式将以三种方式发展，这取决于是否考虑了羽流动量和穿透夹带。尽管对应于三种流态的预测之间的差异很小，