Development of high-speed aerodynamic simulator of aerobraking spacecraft

研究了用于气动拦阻航天器气动特性仿真的大规模并行计算系统。模拟方案为直接模拟蒙特卡罗方法，该方法被广泛应用于稀薄气体流动。对大规模并行计算系统的单元进行了概念设计。研究发现，大规模并行计算系统的单元采用流水线的方法实现，并且不是由中央处理单元组成，而是由分布式处理单元组成。该装置成功地进行了试制，显示了预期的计算性能。该单元的计算性能与系统时钟的速度成正比，对于20 MHz的系统时钟，其计算性能约为0.3GFLOOPS。通过适当的系统制造可以获得更多的计算性能。此外，通过将单元实现为集成电路，计算性能将显着提高。目前计算性能的瓶颈是主机之间的通信速度，这可以通过像PCI这样的更高速的通信基础系统来提高。同时发现本计算系统的思想适用于各种流体运动的模拟方案。特别是格子Boltzmann方法更适合于这样的应用。对基于LB方法的流体模拟计算系统进行了概念设计。

The massively parallel computing system for simulating the aerodynamic characteristics of the aerobraking spacecraft was investigated. The simulation scheme is the direct simulation Monte Carlo method, which is widely used for the rarefied gas flow. the conceptural design for the unit of the massively parallel computing system was carried out. It is found that the unit of the massively parallel computing system is realized by the pipeline method, and is composed not of the central procession unit but of the distributed processing units. The trail manufacturing of the unit was successfully conducted and demonstrated the computation performance as was expected. The computation preformance of the unit is proportional to the system clock sped and reached about 0.3 GFLOOPS for the 20 MHz system clock. The more computational performance can be attained by a proper manufacturing of the system. Furthermore the computational performance will be significantly enhanced by realizing the unit as an integrated circuit. The bottle neck of the present computational performance is the communication speed between the host computer, which can be improved by means of more high-speed communication bas system like PCI.It is also found the idea for the present computing system is applicable to various simulation schemes for the fluid motion. Especially the LB (Lattice Boltzmann) method is suitable to such an application. The conceptual disign for the computing system for the fluid simulation based on LB method was carried out.