4 research outputs found
A fast GPU Monte Carlo Radiative Heat Transfer Implementation for Coupling with Direct Numerical Simulation
We implemented a fast Reciprocal Monte Carlo algorithm, to accurately solve
radiative heat transfer in turbulent flows of non-grey participating media that
can be coupled to fully resolved turbulent flows, namely to Direct Numerical
Simulation (DNS). The spectrally varying absorption coefficient is treated in a
narrow-band fashion with a correlated-k distribution. The implementation is
verified with analytical solutions and validated with results from literature
and line-by-line Monte Carlo computations. The method is implemented on GPU
with a thorough attention to memory transfer and computational efficiency. The
bottlenecks that dominate the computational expenses are addressed and several
techniques are proposed to optimize the GPU execution. By implementing the
proposed algorithmic accelerations, a speed-up of up to 3 orders of magnitude
can be achieved, while maintaining the same accuracy
Ray-traced radiative transfer on massively threaded architectures
In this thesis, I apply techniques from the field of computer graphics to ray tracing in
astrophysical simulations, and introduce the grace software library. This is combined
with an extant radiative transfer solver to produce a new package, taranis. It allows
for fully-parallel particle updates via per-particle accumulation of rates, followed by a
forward Euler integration step, and is manifestly photon-conserving. To my knowledge,
taranis is the first ray-traced radiative transfer code to run on graphics processing
units and target cosmological-scale smooth particle hydrodynamics (SPH) datasets.
A significant optimization effort is undertaken in developing grace. Contrary to
typical results in computer graphics, it is found that the bounding volume hierarchies
(BVHs) used to accelerate the ray tracing procedure need not be of high quality; as a
result, extremely fast BVH construction times are possible (< 0.02 microseconds per
particle in an SPH dataset). I show that this exceeds the performance researchers might
expect from CPU codes by at least an order of magnitude, and compares favourably
to a state-of-the-art ray tracing solution. Similar results are found for the ray-tracing
itself, where again techniques from computer graphics are examined for effectiveness
with SPH datasets, and new optimizations proposed. For high per-source ray counts
(≳ 104), grace can reduce ray tracing run times by up to two orders of magnitude
compared to extant CPU solutions developed within the astrophysics community, and
by a factor of a few compared to a state-of-the-art solution.
taranis is shown to produce expected results in a suite of de facto cosmological
radiative transfer tests cases. For some cases, it currently out-performs a serial, CPU-based
alternative by a factor of a few. Unfortunately, for the most realistic test its
performance is extremely poor, making the current taranis code unsuitable for cosmological
radiative transfer. The primary reason for this failing is found to be a small
minority of particles which always dominate the timestep criteria. Several plausible
routes to mitigate this problem, while retaining parallelism, are put forward
Ray Tracing Gems
This book is a must-have for anyone serious about rendering in real time. With the announcement of new ray tracing APIs and hardware to support them, developers can easily create real-time applications with ray tracing as a core component. As ray tracing on the GPU becomes faster, it will play a more central role in real-time rendering. Ray Tracing Gems provides key building blocks for developers of games, architectural applications, visualizations, and more. Experts in rendering share their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware. What you'll learn: The latest ray tracing techniques for developing real-time applications in multiple domains Guidance, advice, and best practices for rendering applications with Microsoft DirectX Raytracing (DXR) How to implement high-performance graphics for interactive visualizations, games, simulations, and more Who this book is for: Developers who are looking to leverage the latest APIs and GPU technology for real-time rendering and ray tracing Students looking to learn about best practices in these areas Enthusiasts who want to understand and experiment with their new GPU