  The immersed boundary method (IB) is an elegant way to fully couple the
motion of a fluid and deformations of an immersed elastic structure. In that
vein, the IB2d software allows for expedited explorations of fluid-structure
interaction for beginners and veterans to the field of computational fluid
dynamics (CFD). While most open source CFD codes are written in low level
programming environments, IB2d was specifically written in high- level
programming environments to make its accessibility extend beyond scientists
with vast programming experience. Although introduced previously by Battista et
al. 2015, many improvements and additions have been made to the software to
allow for even more robust models of material properties for the elastic
structures, including a data analysis package for both the fluid and immersed
structure data, an improved time-stepping scheme for higher accuracy solutions,
and functionality for modeling slight fluid density variations as given by the
Boussinesq approximation.
