For design and management of large scale tunnels, it is important to model the transitions between pressurized and free-surface flows inside them. The pressurized and free-surface flow regimes are separated by a discontinuity with different wave speeds on two sides, which makes efficient and accurate simulations still challenging. A robust and conservative space-time adaptive mesh refinement (AMR) strategy is proposed to simulate such transient mixed flow. In the present AMR, the mesh resolution is refined adaptively near the interface between two flow regimes, and the flow states at child meshes are determined by a conservative approach which can avoid numerical oscillations. The numerical results from the AMR strategy are validated with analytical and experimental results, which indicates its good ability to capture the interface between two flow regimes and prevent numerical oscillations. The numerical test in a field scale tunnel shows that AMR can speed up simulations of transient mixed flow by 60 times.

对于大型隧道的设计和管理，对其中的加压流与自由面流之间的过渡进行建模非常重要。压力和自由表面的流动状态被不连续的，具有不同波速的两侧分开，这使得有效而准确的模拟仍然具有挑战性。提出了一种鲁棒且保守的时空自适应网格细化（AMR）策略来模拟这种瞬时混合流。在当前的AMR中，网格分辨率在两个流态之间的界面附近进行自适应调整，并且子网格上的流态通过可以避免数值振荡的保守方法确定。通过分析和实验结果验证了AMR策略的数值结果，这表明它具有很好的捕获两个流动状态之间的界面并防止数值波动的能力。在现场规模的隧道中进行的数值测试表明，AMR可以将瞬态混合流的仿真速度提高60倍。