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Being able to predict the spread of pollution in the atmosphere is
another important task ensuring the opportunity to warn people in
advance in case of accidents and failures on industrial units, gas
pipelines, nuclear power stations, etc. Here the term pollution density
can be used to denote the concentration level of toxic gases, the radiation
level or the minimal concentration of combustible gas which can initiate
combustion or explosion. Generally speaking, this phenomenon is a non-steady
three-dimensional process. The GasDynamicsToolR package allows to compute
three-dimensional non-steady processes in multicomponent gas systems.
However, considering the fact that pollution and emissions are as a rule
heavier than the air and spread out in a comparatively small area adjoining
to the ground surface, it is more efficient to simulate these processes
within the quasi-three-dimensional or plane models.
Instant blast
This case implies short-time emissions (for example, explosion of a tanker with chlorine, short-time gas pipeline leakage, etc.).
The figure on the left represents the spreading of heavy gas
concentration in successive time points after the blast close
to the inhabited area. At the initial point of time all the gas
was concentrated in the left-hand lower corner of the denumerable
domain. The wind is directed cornerwise into the right-hand upper
corner. Buildings and constructions are represented in black color.
The figure on the right represents a similar process but with
the presence of reacting gases. The process of fuel efflux goes
on over a certain period of time, then the lighting takes place.
The fuel burns out in the detonation wave, and this is clearly seen
in the presented animation, showing the fuel concentration changes
in space in the course of time.
Air pollution by city traffic
Traffic is another source of considerable air pollution in cities,
which adversely affects the health of the people who live and work
in the immediate vicinity of the roads. Thus, estimation of concentration
of pollutants around the roads is of great interest. The figure presents
the calculation results for a section of the Lenin prospect in the city of Tula.
Karman effect
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Carman effect and the obstruction airflow. Approach flow velocity equals 100m/s. Adiabatic exponent allocation
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Body airflows often entail a periodic flow, known as Carman track.
To compute this effect at the boundary of the denumerable domain we
have introduced two gas sources with the adiabatic exponent only
slightly differing from that of the main gas. This allows to visualize
the flow and see the generation and propagation of vortices. In this
very task the flow velocity equaled 100 m/s.
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