DREAM-1A: special-purpose computer for computational fluid dynamics

Abstract

We have developed a special-purpose computer for computational fluid dynamics, DREAM-1A. DREAM-A has a peak speed of 80 Mflops and a memory size of 1.6 Gbyte. DREAM-1A consists of four units connected in a one-dimensional bidirectional ring network. One unit of DREAM-1A has one vector processing unit (VPU) and one hard-disk unit. The physical variables are stored in hard disk, instead of RAM. The peak speed of a VPU is 20 Mflops. The capacity and the data-transfer rate of the hard-disk unit are 400 Mbyte and 1 Mbyte/s. We implemented one- and two-dimensional fluid dynamics codes on one unit of DREAM-1A. The sustained computing speed of this unit was 6.4 Mflops for 1-D and 3.6 Mflops for 2-D. In 1-D calculation, all variables are stored in small RAM in VPU, while in L-D calculation, data are stored in hard disk. Thus the speed of 6.4 Mflops represent the raw performance of VPU, while the slow down to 3.6 Mflops of the 2-D simulations represent the performance of the total system. The speed of data transfer between processor unit is 40 Mbyte/s. We are implementing 2-D and 3-D fluid dynamics codes on the parallel DREAM system. DREAM-1A will have a sustained computing speed of 14 Mflops and will be able to perform a [256]/sup 3/ 3-D fluid calculation in 3-8 days. >