Navier-Stokes problem for shared memory AMGCL benchmarks

The system matrix and the right hand side used in the shared memory Navier-Stokes benchmark at https://github.com/ddemidov/amgcl_benchmarks.

This is an incompressible Navier-Stokes problem discretized on a non uniform 3D mesh with a finite element method. The overall system matrix for the problem was assembled in the [Kratos](http://www.cimne.com/kratos/) multi-physics package developed in CIMNE, Barcelona. The matrix has block structure with blocks of 4-by-4 elements, and contains 713'456 unknowns and 41'277'920 nonzeros.

本数据集提供了共享内存环境下纳维-斯托克斯（Navier-Stokes）基准测试所用的系统矩阵与右端项，相关基准测试内容可通过 https://github.com/ddemidov/amgcl_benchmarks 查阅。

本数据集对应的是不可压缩纳维-斯托克斯问题，采用有限元方法在非均匀三维网格上进行离散化。该问题的整体系统矩阵由巴塞罗那国际工程数值方法中心（CIMNE）开发的多物理场软件包Kratos（http://www.cimne.com/kratos/）组装生成。该矩阵采用4×4元素分块结构，总计包含713456个未知量与41277920个非零元素。