PySPH is an open-source, Python-based, framework for particle methods in general and Smoothed Particle Hydrodynamics (SPH) in particular. PySPH allows a user to define a complete SPH simulation using pure Python. High-performance code is generated from this high-level Python code and executed on either multiple cores, or on GPUs, seamlessly. It also supports distributed execution using MPI. PySPH supports a wide variety of SPH schemes and formulations. These include, incompressible and compressible fluid flow, elastic dynamics, rigid body dynamics, shallow water equations, and other problems. PySPH supports a variety of boundary conditions including mirror, periodic, solid wall, and inlet/outlet boundary conditions. The package is written to facilitate reuse and reproducibility. This article discusses the overall design of PySPH and demonstrates many of its features. Several example results are shown to demonstrate the range of features that PySPH provides.

Vortex methods offer a grid-free alternative to simulating incompressible, viscous, fluid flows. They require the use of fairly sophisticated algorithms and can be complicated to implement for general flows. This article describes an object-oriented design used to implement a vortex particle based flow solver in two dimensions. We provide an overview of the various abstractions that arose as a result of this design. Several of the algorithms have common components that may be abstracted and reused. We demonstrate how the design allowed us to derive the traditional benefits of OOD. In addition, we show how the design directly suggested elegant generalizations of existing algorithms. Finally, we show the benefits of using software testing techniques and building a powerful scripting layer for the library.