Reynolds-stress turbulence model in the KIVA code for engine simulation

A Reynolds-Stress Turbulence Model has been incorporated with success into the KIVA code, a computational fluid dynamics hydrocode for three-dimensional simulation of fluid flow in engines. The newly implemented Reynolds-stress turbulence model greatly improves the robustness of KIVA, which in its original version has only eddy-viscosity turbulence models. Validation of the Reynolds-stress turbulence model is accomplished by conducting pipe-flow and channel-flow simulations, and comparing the computed results with experimental and direct numerical simulation data. Flows in engines of various geometry and operating conditions are calculated using the model, to study the complex flow fields as well as confirm the model’s validity. Results show that the Reynolds-stress turbulence model is able to resolve flow details such as swirl and recirculation bubbles. The model is proven to be an appropriate choice for engine simulations, with consistency and robustness, while requiring relatively low computational effort.

EFFECTIVE FUNCTION CHOICE IN THE R SCRIPTING LANGUAGE

This project examines the current available work on the explicit and implicit parallelization of the R scripting language and reports on experimental findings for the development of a model for predicting effective points for automatic parallelization to be performed, based upon input data sizes and function complexity. After finding or creating a series of custom benchmarks, an interval based on data size and time complexity where replacement becomes a viable option was found; specifically between O(N) and O(N3) exclusive. As data size increases, the benefits of parallel processing become more apparent and a point is reached where those benefits outweigh the costs in memory transfer time. Based on our observations, this point can be predicted with a fair amount of accuracy using regression on a sample of approximately ten data sizes spread evenly between a system determined minimum and maximum size.