Simulations

The Simulation file allows the user to set up the parameters for each individual simulation. These parameters include the maximum simulation time, the time step, maximum occupant density allowed in a node and details regarding the flow calculation algorithm

Times

The <TimeStep> element sets the time step in seconds. Typically values of 1.0 s are sufficient but smaller values should be considered as part of a sensitivity analysis. Smaller time steps will lead to longer simulation times and larger output files. Time steps of less than 0.1 s are not recommended.

<TimeStep>value</TimeStep>

The <TimeMax> element sets the time in seconds when Evacuationz will terminate the simulation regardless of whether every occupant has reached a place of safety. This parameter useful in case occupants get stuck and so prevents the model getting into a never ending loop. A simulation will terminate before the maximum time if all occupants reach safety first. If this element is not defined then a default value of 1800 s (30 min) is used.

<TimeMax>value</TimeMax>

The <TimeFrequency> element sets the frequency of the console output when a simulation is running. The default value is 120 s.

<TimeFrequency>value</TimeFrequency>

The above three time elements can use the units attribute to use alternative time units. For example

<TimeMax units="minutes">value</TimeMax>

Specific flow

The <SpecificFlow> element can be used to define the maximum specific flow through a door or similar constriction. A user defined fixed maximum specific flow can be set for all constrictions using the type=”enz_fixed“ attribute.

A maximum specific flow can also be selected using a distribution using type=”enz_distribution“ attribute and either the same value applied to all constrictions or a different value applied to each individual constriction. Using the application=”enz_global“ attribute sets the same maximum specific flow to each constriction while application=”enz_individual“ applies a different maximum specific flow to each individual constriction. If the <SpecificFlow> element is not defined then a maximum specific flow of 1.33 ppl/s/m effective width will be used. Maximum specific flows must be between 0.10 ppl/s/m and 2.50 ppl/s/m effective width. The default specific flow should be used in most cases as Evacuationz has been calibrated using this value.

<SpecificFlow type="enz_distribution" application="enz_individual">
    <Distribution type="enz_normal">
        ...
    </Distribution>
</SpecificFlow>

Defaults

The default time step is 1.0 s, maximum occupant density is 2.75 ppl/m², specific flow is 1.33 ppl/s/m effective width.