Expression Templates Revisited: A Performance Analysis of the Current ET Methodology

In the last decade, Expression Templates (ET) have gained a reputation as an efficient performance optimization tool for C++ codes. This reputation builds on several ET-based linear algebra frameworks focused on combining both elegant and high-performance C++ code. However, on closer examination the assumption that ETs are a performance optimization technique cannot be maintained. In this paper we demonstrate and explain the inability of current ET-based frameworks to deliver high performance for dense and sparse linear algebra operations, and introduce a new "smart" ET implementation that truly allows the combination of high performance code with the elegance and maintainability of a domain-specific language.Comment: 16 pages, 7 figure

Simulation of moving particles in 3D with the Lattice Boltzmann method

AbstractThe following paper presents a way to simulate the behavior of particle agglomerates in a fluid flow by coupling the Lattice Boltzmann Method to a rigid body physics engine. By extending the basic algorithm by a fluid/particle force interaction method, the hydrodynamic forces acting on the particles can be calculated. By the use of this force interaction between the fluid and the particles and by the use of the rigid body physics engine, the movement and collision behavior of particles in a flow can be simulated. Additionally, this coupled simulation system is able to simulate the internal particle forces in the connections between sintered particles, which could break due to the forces and torques of a shear flow. This permits a prediction of possible break-ups or structural displacements