Parallelisation of an interactive lattice-Boltzmann method on an Android-powered mobile device

- The role of mobile devices in interactive engineering simulation is discussed.
- Two parallelisation frameworks for simulation on Android-based mobile devices are presented.
- Task-based parallelisation performs slightly better than thread-based parallelisation.
- Implementing the kernel natively improves performance by 20%.

Engineering simulation is essential to modern engineering design, although it is often a computationally demanding activity which can require powerful computer systems to conduct a study. Traditionally the remit of large desktop workstations or off-site computational facilities, potential is now emerging for mobile computation, whereby the unique characteristics of portable devices are harnessed to provide a novel means of engineering simulation. Possible use cases include emergency service assistance, teaching environments, augmented reality or indeed any such case where large computational resources are unavailable and a system prediction is needed. This is particularly relevant if the required accuracy of a calculation is relatively low, such as cases where only an intuitive result is required. In such cases the computational resources offered by modern mobile devices may already be adequate. This paper proceeds to discuss further the possibilities that modern mobile devices might offer to engineering simulation and describes some initial developments in this direction. We focus on the development of an interactive fluid flow solver employing the lattice Boltzmann method, and investigate both task-based and thread-based parallel implementations. The latter is more traditional for high performance computing across many cores while the former, native to Android, is more simple to implement and returns a slightly higher performance. The performance of both saturates when the number of threads/tasks equal three on a quad-core device. Execution time is improved by a further 20% by implementing the kernel in C++ and cross-compiling using the Android NDK.