Displaying dynamic concentration grid

In EFFECTS, dispersion models can generate a "Concentration profile grid" to visualise the time-dependent location of a flammable or toxic cloud. This grid helps in understanding the dispersion of flammable or toxic substances over time.

Types of dispersion models and their dynamic legends

• Flammable models: The colour legend is based on Lower Flammability (LFL) levels.

• Dispersion - Toxic Dose model: The colour legend reflects lethality-associated concentrations.

• Dispersion - Concentration model: The colour legend is based on a specific threshold, which can be selected in the "Grid-scale based on" input field of the dispersion model. Available thresholds may include IDLH, ERPGs, AEGLs, LFL, and UEL, depending on the substance.

Displaying dynamic grid

To enable and view the dynamic concentration grid:

1. In the model input panel, enable the dynamic concentration grid.

2. Recalculate the model result to generate the dynamic grid.

3. The dynamic concentration grid will be added as a model contour.

Note

If the receiver ‘‘Congestion area’’ is connected to the model, the dynamic concetration grid will be enabled automatically to determine the maximum LFL cloud overlap.

Working with the dynamic grid

• Control buttons

  • At the bottom of the screen, use the Play, Pause, Forward, Backward buttons and the time slider to illustrate the movement of the cloud over time.

  • The play button will animate the cloud movement, while the pause button allows you to position the cloud at any time step by dragging the slider.

• Manual time entry

  • Enter a fixed value below the slider and press <Enter> to set the cloud position at the specified time.

• Multiple dynamic grids

  • If a model contains multiple "Dynamic Grids" (a combined model may run both instantaneous and pool source dispersion calculations), use the selection box at the lower right to choose which cloud time to control with the buttons.

    

Tip

You can freeze the grid at any time step to compare the cloud concentration grid at different time steps.

Note

The dynamic concentration grid displays levels at the reporting/receiver height (Zd) for concentration, toxic dose, and flammable dispersion models. Outer contours in concentration and flammable cloud models are presented from the top view, combining all heights. Additionally, these concentration and flammable cloud dispersion models will also present a contour "at height Zd"

By utilising these features, you can effectively analyse and interpret the dispersion of hazardous substances, ensuring better preparedness and response in case of accidental releases.