Chapter 58
Model of Arrival Time for Gas Clouds
in Urban Canopy
Hana Chaloupecká, Zbynˇ ek Ja ˇ
nour, Klára Jurˇ cáková and Radka Kellnerová
Abstract The aim of this paper is to present a new model of arrival time for gas
clouds. To create such a model, simulations of short-term gas leakages were conducted in a wind tunnel with a neutrally stratified boundary layer. Into the tunnel, a
model of an idealized urban canopy in scale 1:400 was placed. For simulations of
the short-term gas discharges, ethane was utilized. Concentration time series were
measured by a fast flame ionisation detector. The experiments were repeated about
400 times to get statistically representative datasets. The ensembles of concentration
time series were measured at about 50 individual positions. From these data, puff
arrival times were computed. The results showed that a suitable probability distribution to describe the variability in values at individual positions for arrival time is
lognormal. Moreover, the parameters of this distribution do not change randomly
with the change in the measurement position but their change can be described by
functions. Utilizing them, probability density functions of arrival time can be constructed and whatever quantile of arrival time at a chosen position can be computed.
Such a model could help emergency services to estimate how the situation could
look like during the accident not only in the most frequently occurred but also in the
extreme cases.
58.1 Introduction
Leakages of gases during an accident last very often less than one hour (e.g., [2]).
The dispersion of these gas clouds depends on the actual turbulent flow present in
the time and the place. Hence, wide range of dispersion scenarios can happen under
the same mean ambient conditions. To be able to react effectively to an accident,
H. Chaloupecká (B) · Z. Jaˇ nour · K. Jurˇ cáková · R. Kellnerová
Institute of Thermomechanics, Czech Academy of Sciences, Prague, Czech Republic
e-mail: hana.chaloupecka@it.cas.cz
H. Chaloupecká
Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_58
363
Model of Arrival Time for Gas Clouds
in Urban Canopy
Hana Chaloupecká, Zbynˇ ek Ja ˇ
nour, Klára Jurˇ cáková and Radka Kellnerová
Abstract The aim of this paper is to present a new model of arrival time for gas
clouds. To create such a model, simulations of short-term gas leakages were conducted in a wind tunnel with a neutrally stratified boundary layer. Into the tunnel, a
model of an idealized urban canopy in scale 1:400 was placed. For simulations of
the short-term gas discharges, ethane was utilized. Concentration time series were
measured by a fast flame ionisation detector. The experiments were repeated about
400 times to get statistically representative datasets. The ensembles of concentration
time series were measured at about 50 individual positions. From these data, puff
arrival times were computed. The results showed that a suitable probability distribution to describe the variability in values at individual positions for arrival time is
lognormal. Moreover, the parameters of this distribution do not change randomly
with the change in the measurement position but their change can be described by
functions. Utilizing them, probability density functions of arrival time can be constructed and whatever quantile of arrival time at a chosen position can be computed.
Such a model could help emergency services to estimate how the situation could
look like during the accident not only in the most frequently occurred but also in the
extreme cases.
58.1 Introduction
Leakages of gases during an accident last very often less than one hour (e.g., [2]).
The dispersion of these gas clouds depends on the actual turbulent flow present in
the time and the place. Hence, wide range of dispersion scenarios can happen under
the same mean ambient conditions. To be able to react effectively to an accident,
H. Chaloupecká (B) · Z. Jaˇ nour · K. Jurˇ cáková · R. Kellnerová
Institute of Thermomechanics, Czech Academy of Sciences, Prague, Czech Republic
e-mail: hana.chaloupecka@it.cas.cz
H. Chaloupecká
Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_58
363