Distributed Immersed Boundary Simulation in Titanium

The immersed boundary method is a general technique for modeling elastic boundaries immersed within a viscous, incompressible fluid. The method has been applied to several biological and engineering systems, including large scale models of the heart and cochlea. These simulations have the potential to improve our basic understanding of the biological systems they model and aid in the development of surgical treatments and prosthetic devices. Despite the popularity of the immersed boundary method and the desire to scale the problems to accurately capture the details of the physical systems, parallelization for large scale distributed memory machine has proven challenging. The primary reason is a classic locality and load balance tradeoff that arises in distributing the immersed boundary data structure across processors. In this paper we describe a parallelized algorithm for the immersed boundary method that is designed for scalability on distributed memory multiprocessors and clusters of SMPs. It is implemented using the Titanium language, a Java-based high performance scientific computing. Our software package, called IB, takes advantage of the object-oriented features of Titanium to provide a framework for simulating immersed boundaries that separates the generic immersed boundary method code from the specific application features that define the immersed boundary structure and the forces that arise from those structures. Our results demonstrate the scalability of our design and the feasibility of large scale immersed boundary computations with the IB package.