Simulation is a modeling technique that uses business process models in a BPMS tool to make predictions about how a process may perform under different circumstances and workloads.
Business process simulation can be either formal or informal and use a variety of techniques. Process simulation usually assigns values to activities and then defines a number of anticipated use cases to see how the business process will respond under different circumstances.
The simulation of complex business processes can often reveal outcomes that business process transformation teams can’t anticipate. This is especially relevant when trying to model new automated business processes being carried out on mobile devices. Simulations require sufficient data, which typically allows the process to be mathematically simulated under various scenarios, loads, or other conditions.
Source: Guide to the Business Process Management Body of Knowledge – ABPMP BPM CBOK V3.0.