AbstractThe concept of programmed splitting of stick propellants offers a new method in controlling pressure‐time traces by increasing the burning surface area at the onset of splitting. This increase in burning surface area, also referred to as progressivity, leads to a higher performance of existing guns. The experimental work on combustion of programmed splitting stick (PSS) propellants in parallel to the present theoretical study was conducted and published by the authors. In this investigation, a theoretical model and computer code have been developed to simulate the burning and splitting processes of PSS charges and to gain a better understanding of physico‐chemical phenomena involved. In this theoretical model, the continuous gas phase is treated by a Eulerian approach, while the condensed phase (stick propellant) is divided into several representative groups and tracked as they move in the continuous phase, using a Lagrangian approach. The intergranular gas‐phase region is treated in a way similar to the continuous phase in the separated flow models for spray combustion. Numerical results are in agreement with experimental data, and can predict several features of the combustion processes that have been observed in partially burned grains recovered from test fi