In 2.5 D simulations, 3D dislocation mechanisms like multiplication, junction formation and destruction, cross-slip or climb are implemented in two-dimensions. In such conditions, the interactions of the blue and red slip systems lead to the formation of a cell structure that follows the similitude relation (D. Gómez-García, B. Devincre and L. Kubin, PRL, 96, 125503, 2006).
Pattern formation in a 2.5 DD simulation