Dynamic Contaminants offer a way to simulate the second-by-second spread of a contaminant through a mine. This simulation differs from the normal ‘steady state’ contaminant and gas simulations in that ventilation models can show contamination progress and concentration at any time. Importantly, it can be dynamically changed during simulation (for example doors opened or close, fans turned off, on or reversed.)
This means that (for example) emergency procedures can be performed in the simulation at any time into the dynamic simulation to see the effect of the changes to the existing spread of the contaminants.
Contaminants are considered ‘unspecified’ in Ventsim, and can be set to any volumetric concentration. For example contaminants could be called ‘Carbon Monoxide’ and the original starting concentration set to 2000 ppm to represent explosive gases or perhaps a fire.
To set a dynamic contaminant, simply use the SMOKE button to place a contaminant and then use the EDIT function to change the concentration, type and length of time the contaminant is emitted for. This simplest dynamic form is a ‘FIXED RELEASE’ option which emits a continuous stream of contaminants at a specified concentration for a specified amount of time. Other more complex options exist to reduce concentration over time, or to simulate explosive quantities.
To release and simulate a dynamic contaminant, simply choose the Contaminant > Dynamic option and the contaminant will immediately start spreading through the mine from the source(s).
The model can be rotated at any time during simulation, and colours of contaminant levels adjusted through the color menu if required.
If a change is to be made to the circuit, the simulation can be paused at any time, and the following steps taken:
- The model is adjusted (for example a door closed, or a fan stopped or reversed).
- An airflow (and heat if required) simulation is performed to simulated the changed airflows.
- The Dynamic Contaminant simulation is resumed to show the new pathway spread of gas from the current areas.
This option can be performed multiple times during simulation, and an idea of the effect of the changes can be quickly gained.For example, if the airflow is reversed, the previous spread of contaminant may show to be ‘pushed’ back as the fresh air clears the previously contaminated areas.