非圧縮性流体の中心差分法によるCFDプログラムの開発とその検証

抄録

When analyzing the flow of incompressible fluid by the difference method, various contrivances had been made to establish the continuity equation strictly. This method added a term to converge the fluctuation of the continuity equation to the Navier-Stokes equation of motion, and solved it by the forward method while allowing some fluctuation of the continuity equation. In this method, a stable solution could be obtained by using a simple central difference and it was already reported that the calculation results of several flow patterns agreed well with the experimental results.

In this report, this calculation method was applied to a well-developed laminar flow in a circular pipe and the disturbance to the velocity distribution was given to investigate the stability of the solution. As a result, it was found that the solution was stable when the Reynolds number was 1400 or less, but diverges when it was 1500 or more.

As a result of a visualization experiment using a vertical 300d circular tube, the streamline was stable when the Reynolds number was 1400 or less, but the streamline fluctuates although it was a laminar flow state when it was 1500 or more.