GASTAR

Advanced software for modelling dense gas dispersion

Model input data

Meteorology

• Wind speed, height and bearing.
• Atmospheric pressure, humidity, air temperature, Monin-Obukhov length or Pasquill-Gifford stability.

Site properties

• Roughness length.
• Surface temperature.

Release

• Chosen from materials database (supplied) or user defined.
• Puff, plume, transient, jet.
• Aerosol (flashing), thermal or isothermal releases.

The pool uptake model uses liquid spill evaporation/boil-off information to calculate plume uptake. To simplify pool uptake, GASTAR interfaces with CERC's comprehensive pool spill model LSMS.

Source details

• Width, mass (flux), temperature, aerosol fraction.
• Height and direction for jets.

Others

• Rectangular and/or circular buildings.
• 2-dimensional walls (solid) and fences (porous).
• Topography through segmented slopes with spatially varying properties (inclination, roughness length, wind speed).

Model output data

Cloud properties along the centre-line

• Time and xyz-position, distance travelled.
• Concentration, mass fraction, width, height, volume, velocity.
• Mass, enthalpy, temperature, density, aerosol fraction, Richardson number.
• Leading and trailing edges (for instantaneous releases).
• Downwind and crosswind dimensions (for instantaneous releases).

The user may choose to add extra output steps by time and/or position, to get the maximum range to particular concentration, gridded concentration output.

Additional output for available for specified output points

• Concentration-time histories.
• Dose and toxic load.

Additional output for available for specified output times

• Flammable output: LFL and half-LFL range, downwind and crosswind radius, maximum height, flammable volume and mass.

Output for GASTAR may be presented graphically with its integrated free-floating graphics screen (x-y plots for all cloud properties; flammable output plots). A tabulated record of user input and all model output is also available.

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