CERC — Environmental Software and Services

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Advanced software for modelling dense gas dispersion

Model input data


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

Site properties

  • Roughness length.
  • Surface temperature.


  • 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.


  • 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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