计算平面环形腔体内的自然对流问题，不可压缩流动，圆柱坐标系，压力速度采用simple算法解耦。计算结果使用tecplot 查看(A numerical simulation of natural convection in the annulus between horizontal concentric cylinders; incompressible flow; the pressure and velocity are uncoupled with SIMPLE method; cylindrical-coordinate system;)