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, while maintaining the same accuracy, a speed-up of up to 3 orders of magnitude can be achieved.