The geometry is created using PHOENICS-VR. An area 70m wide by 70m deep by 10m high is considered. A non-uniform Cartesian grid of 50*50*15 cells is used. Equations are solved for pressure, three velocity components, the temperature, and a pollutant gas concentration. Turbulence is modelled using the standard k-e model.
The geometry and grid are shown inFig3.gif
The ceiling vents are assumed to blow air in at 1m/s, and at a temperature of 20° C. The floor is held at 22° C. The ceiling vents and main entrance and exit are held at atmospheric pressure, with an external temperature of 20° C.
Four rows of three parked vehicles are considered. A single pollution source is located near the rear of one of the vehicles - the engine has been left running. At this location, the temperature is fixed to 30° C, and the pollutant concentration is held at 1.0.
The geometry took 2 hours to set up, and the calculation approximately 5 hours for 1000 iterations on a 266MHz Pentium II.
The results are visualised with PHOENICS-VR 3.2.
The following pictures are supplied as GIF files:
Velocity vectors near the floor. The impact points of the ceiling jets can be seen. It is likely that the inlet air velocity is too high, and/or the inlets should have been angled horizontally across the roof space.
Isosurface of pollutant concentration.
Velocity vectors at approximately head height.
Fig7, Fig8, Fig9,
Fig10.gif Here the jets can be clearly seen, and the entrainment of surrounding air.
FigS8 - 10 are then progressively nearer to the observer, and show the
downward-moving air starting to go up.
This is the 'fountain effect' by which the jets hit the floor, spread
sideways and then are forced up again by air from the surrounding jets.
A sequence of velocity vector plots, starting in the plane of one row of ceiling vents (Fig7).
Here the jets can be clearly seen, and the entrainment of surrounding air.
FigS8 - 10 are then progressively nearer to the observer, and show the downward-moving air starting to go up.
This is the 'fountain effect' by which the jets hit the floor, spread sideways and then are forced up again by air from the surrounding jets.
This shows a view of the parked vehicles from inside the passer exchange.
These show isosurfaces of pollutant concentration in the vicinity of the pollutant source. The higher values are found nearer the source.
Velocity vectors at approximately head height, viewed from inside the terminal. The upward fountains mentioned above can clearly be seen.