The formed jet has a linear velocity gradient along its length, causing the jet to stretch longitudinally. The stretching of the jet continues until a break-up criterion is met.

JETBREAK uses a break criterion that incorporates the Hirsch plastic velocity, the strain rate at the stagnation point, and two constants. The number of particles formed as the jet breaks is a function of the difference in velocity between the front and back end of the jet divided by the Hirsch plastic velocity.

Once a particle breaks from the jet, stretching of the individual particle is assumed to cease. The particle continues to travel at the average velocity of its front and aft end just as it separated from the remainder of the jet. The length and velocity of each particle as it strikes a target are important factors in determining the penetration of the jet.

The figure above is an ATJETSuite representation of a fully particulated jet.

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