A Parallel Algorithm For Laser Propulsion Of Three Dimensional And Multi-Subdomain

Laser propulsion is a brand-new propulsive technology. Compared with the classical chemical rocket propulsion, it has higher payload capacity and lower launches cost, and it is significant for the future nation security and enhancing the ability of national defense strength. The numerical simulation of laser propulsion is a key link between basic research and application process; it mainly includes energy conversion process, fluid field evolvement rule and the generation of thrust in laser propulsion system. This simulation can depict the temporal and spatial variation characters of the flow fields accurately which can't be measured in experiment, but the computational task of the numerical simulation is heavy and calculation period is long. In order to accelerate the mechanism research of laser propulsion in diversified conditions, we should use the parallel technology to shorten the computational time.This thesis aim at the numerical simulation of the light focusing, energy deposition and fluid field evolvement, which are referred in pulses laser propulsion under air-breathing mode. We set the Euler equation as the control equation and use the radiation equation to receive the energy source term. In solving the Euler equations, the cell centered finite volume method is used for space discretization, and five step Runge-Kutta method is adopted for time marching. As to the boundary condition, we consider the open boundary, solid wall and simple boundary, and we provide coupled processes for the interface between multi-subdomain. Based on domain decomposition strategy, the initial calculation region is split into smaller blocks. Blocks are distributed over the processors on the parallel computer according to taking the full advantage of space locality of the light and setting the weighted load of the flow field grid to achieve good load balancing. We improve cache hit rate through defining the global array and local array for the energy source term and flow field and strengthening utilization of data space. We optimize the message passing between computing nodes by use overlap of computation and communication and combine the little message into a large one, etc. And realize communication overhead reduce from O(N₂) to O(N)(N is the number of network nodes) through simplifying the complex coupling process of the interface between multi-subdomain. Finally, We design and implement parallel I/O strategy to solve fluid field evolvement data preservation.We realized a laser propulsion parallel algorithm which suits various focusing systems and different configurations of lightcraft. We did a lot of tests about the validity and the parallel performance of this algorithm in different parallel environment. The calculated results analysis showed that: The error of the algorithm can be controlled in a limit range, so we see the algorithm does well in validity. According to the aggrandizement of calculation scale, the algorithm can enhance its performance, as to the large scale computing, the algorithm shows a linear speedup and present an excellent parallel efficiency, so it has a good scalability. The algorithm also performs so well on different calculation models that it can be applied in many conditions.The laser propulsion parallel algorithm proposed by this paper shortens the period of the research on laser propulsion theory extremely, and it plays an important role in the progress of experiment and research.