104 Ballistics: Theory and Design of Guns and Ammunition
regresses and stretches as the propellant is burned. These codes are usually very good but
the user should completely understand the assumptions on how the propellant is allowed
to move before using them.
A two-dimensional model is one where the density can vary in the radial direction
as well. These models are better at predicting pressure waves but take somewhat longer
time to run than one-dimensional models. Pressure can be tracked in the radial direc-
tion and the propellant motion included. The same issues with propellant motion are
present as they were in the one-dimensional models though it is possible to track propel-
lant motion.
A three-dimensional model has it all. Because of t ...