Development of a platform for analyses of ultra-scale direct numerical simulation data of turbulence

在地球模拟器上进行了不可压缩均匀湍流的超尺度直接数值模拟。网格点的个数达到4096^3，是以前DNS的64倍。得到的泰勒微尺度雷诺数高达1200。由于湍流的超尺度DNS数据具有解释高雷诺数湍流的潜在能力，因此希望将数据公开。在本研究中，为了开发湍流的超尺度DNS数据分析平台，我们做了以下研究：(1)发布了超尺度DNS获得的高雷诺数湍流的基本特征和各种数据分析结果。分析包括能谱、压力谱、熵谱和耗散谱，以及高雷诺数湍流中速度导数的PDF和高阶矩。研究结果是这些量在高雷诺数湍流中的各种新的渐近性质。(2)开发了用于分析湍流超尺度DNS数据的通用程序。程序用FORTRAN和MPI语言编写。可以在ES和名古屋大学信息技术中心的vpp5000/56系统上分析超大规模DNS数据。(3)我们已经把DNS数据放到了互联网上，最多1024^3个网格点（可以从以下URL下载数据：http://www.fluid.cse.nagoya-u.ac.jp/~dns/pub/dnsdata/dns.html）。我们还在名古屋大学信息技术中心提供了2048^3 DNS数据。(4)成功实现了超尺度湍流场的可视化。(5)我们还进行了通道湍流的大规模DNS。网格点个数为1024x512x1024，得到的摩擦雷诺数Reτ为1300。

We have performed ultra-scale direct numerical simulations(DNS) of incompressible homogeneous turbulence on the Earth Simulator. The number of grid points is up to 4096^3, the size of which is 64 as large as previous DNS. The attained Taylor micro-scale Reynolds number is as high as 1200. Since the ultra-scale DNS data of turbulence have a potential ability to elucidate high-Reynolds number turbulence, it is desirable to make the data public.In this research, for the purpose of developing a platform for analyses of the ultra-scale DNS data of turbulence, we have made the following studies :(1)We have released the fundamental characteristics as well as the results of various data-analyses of high-Reynolds number turbulence obtained by the ultra-scale DNS. The analyses include those of energy spectrum, pressure spectrum, enstrophy, and dissipation spectra, and the PDF and high-order moments of velocity derivatives in high Reynolds number turbulence. The findings are various new asymptotic properties of these quantities in high-Reynolds number turbulence.(2)We have developed general-purpose programs for the purpose of analyzing the ultra-scale DNS data of turbulence. The programs were written in FORTRAN and MPI. One can analyze the ultra-scale DNS data both on the ES and on the vpp5000/56 system of Information technology center at Nagoya University.(3)We have put the DNS data up to 1024^3 grid points on the Internet (one can download the data from the following URL : http://www.fluid.cse.nagoya-u.ac.jp/~dns/pub/dnsdata/dns.html). We have also made the 2048^3 DNS data available on Information technology center at Nagoya University.(4)We have succeeded on visualizing the ultra-scale turbulence field.(5)We have also performed a large-scale DNS of channel turbulence. The number of grid points is 1024x512x1024 and the attained friction Reynolds number Reτ is 1300.