chama.simulation module

The simulation module contains methods to run Gaussian air dispersion models. Chama can also integrate simulations from third party software for additional sensor placement applications.

Contents

Grid(x, y, z)

Defines the receptor grid.

Source(x, y, z, rate)

Defines the source location and leak rate.

GaussianPlume(grid, source, atm[, gravity, …])

Defines the Gaussian plume model.

GaussianPuff([grid, source, atm, tpuff, …])

Defines the Gaussian puff model.

class chama.simulation.Grid(x, y, z)[source]

Bases: object

Defines the receptor grid.

Parameters
  • x (numpy array) – x values in the grid (m)

  • y (numpy array) – y values in the grid (m)

  • z (numpy array) – z values in the grid (m)

class chama.simulation.Source(x, y, z, rate)[source]

Bases: object

Defines the source location and leak rate.

Parameters
  • x (float) – x location of the source (m)

  • y (float) – y location of the source (m)

  • z (float) – z location of the source (m)

  • rate (float) – source leak rate (kg/s)

class chama.simulation.GaussianPlume(grid, source, atm, gravity=9.81, density_eff=0.769, density_air=1.225)[source]

Bases: object

Defines the Gaussian plume model.

Parameters
  • grid (chama Grid) – Grid points at which concentrations should be calculated

  • source (chama Source) – Source location and leak rate

  • atm (pandas DataFrame) – Atmospheric conditions for the simulation. Columns include ‘Wind Direction’, ‘Wind Speed’, and ‘Stability Class’ indexed by the time that changes occur.

  • gravity (float) – Gravity (m2/s), default = 9.81 m2/s

  • density_eff (float) – Effective density of the leaked species (kg/m3), default = 0.769 kg/m3

  • density_eff – Effective density of air (kg/m3), default = 1.225 kg/m3

run()[source]

Computes the concentrations of a Gaussian plume.

class chama.simulation.GaussianPuff(grid=None, source=None, atm=None, tpuff=1, tend=None, tstep=10, gravity=9.81, density_eff=0.769, density_air=1.225)[source]

Bases: object

Defines the Gaussian puff model.

Parameters
  • grid (chama Grid) – Grid points at which concentrations should be calculated

  • source (chama Source) – Source location and leak rate

  • atm (pandas DataFrame) – Atmospheric conditions for the simulation. Columns include ‘Wind Direction’,’Wind Speed’, and ‘Stability Class’ indexed by the time that changes occur.

  • tpuff (float) – Time between puffs (s)

  • tend (float) – Total time to run the simulation (s). Must be divisible by tpuff

  • tstep (float) – Time step for reporting concentration information (s)

  • gravity (float) – Gravity (m2/s), default = 9.81 m2/s

  • density_eff (float) – Effective density of the leaked species (kg/m3), default = 0.769 kg/m3

  • density_air (float) – Effective density of air (kg/m3), default = 1.225 kg/m3

run(grid, tstep)[source]

Computes the concentrations of a Gaussian puff model.

Parameters
  • grid (chama Grid) – Grid points at which concentrations should be calculated

  • tstep (float) – Time step for reporting concentration information (s)