In many tissue engineering applications it is essential to understand how cells orient under the influence of their mechanical environment. In vitro engineered models are used to investigate the orientation of F-actin stress fibers inside cells. One such in vitro model [1] consists of a mixture of cells, collagen and matrigel, that is constrained by an array of silicone posts (Figure 1). We have recently developed a computational model to describe the orientation of stress fibers in response to their mechanical environment [2]. In the present study, this computational model is extended to 3D and used to simulate cell behavior in the mentioned in vitro model. This improves our understanding of how stress fibers orient in response to the mech...