Abstract: Apparatuses and methods for simulating the interaction of units, such as military units interacting on the battlefield, are disclosed. Embodiments utilize equations representing conservation of individuals and/or the ability to track the identity of unit components (“sub-units”). Further embodiments utilize fluid flow models for calculating personnel movement and/or formulating results as a probability distribution of where personnel are likely to be found after one or more time periods. Still further embodiments use terrain, overlays to the terrain (impediments) and/or casualties to influence group movement. Embodiments present information as contour lines of equal potential for locating personnel and/or casualties. Still further embodiments allow simulations to be run while changing various parameters to give predictive models of what is likely to occur.