Environmental diffusion

当一种可能是恶臭、易燃或有毒的气体被释放到大气边界层时，人们希望知道在不同地点和时间遇到的可能浓度值。这些浓度值很难预测或测量，环境处于湍流状态，在现场（以及实验室）测量中记录的非常不规则的浓度值通常显示出浓度的极端偏移，是标称平均水平的许多倍。用于浓度值的量化的通常描述符是概率密度函数，然而这在环境背景下是不切实际的。 提出了一种新的浓度值量化方法。新的措施-预期的质量分数函数-具有显着的优势，无论是在相对简单的方程，其演变和相对少量的测量浓度数据需要编译此统计。 该建议是实验和理论研究的污染物浓度值的行为，使用预期的质量分数函数。

When a gas, which may be malodorous, flammable or toxic, is released into the atmospheric boundary-layer one would like to know the probable concentration values encountered at various locations and times. These concentration values are very difficult to predict or to measure.The environment is in a turbulent state and the very irregular values of concentration recorded in field (and also in laboratory) measurements commonly exhibit extreme excursions of concentration that are many times the nominal average level. The usual descriptor used for the quantification of concentration values is the probability density function however this is impractical in the environmental context.  A new measure for quantifying concentration values has been proposed. The new measure-The Expected Mass Fraction Function-has significant advantages both in terms of the relative simplicity of the equations that govern its evolution and in the relatively small amount of measured concentration data required to compile this statistic.  The proposal is to experimentally and theoretically investigate the behaviour of contaminant concentration values using the Expected Mass Fraction Function.