论文标题
部分可观测时空混沌系统的无模型预测
On the Dynamics of Imploding and Exploding Spherical Shock Wave Inside a Shock Tube
论文作者
论文摘要
储层计算是预测湍流的有力工具，其简单的架构具有处理大型系统的计算效率。然而，其实现通常需要完整的状态向量测量和系统非线性知识。我们使用非线性投影函数将系统测量扩展到高维空间，然后将其输入到储层中以获得预测。我们展示了这种储层计算网络在时空混沌系统上的应用，该系统模拟了湍流的若干特征。我们表明，使用径向基函数作为非线性投影器，即使只有部分观测并且不知道控制方程，也能稳健地捕捉复杂的系统非线性。最后，我们表明，当测量稀疏、不完整且带有噪声，甚至控制方程变得不准确时，我们的网络仍然可以产生相当准确的预测，从而为实际湍流系统的无模型预测铺平了道路。
The present work aims to study the phenomenon of shock wave focusing and the effect of viscosity in it. The focusing is achieved with a shock tube and a converging section attached to it. The converging section transforms the planar shock into a spherical shock and focuses it into a confined area. A shock of an initial strength Ms=2.94 has been chosen for the present studies. A detailed numerical study of the focusing region shows the formation of a mushroom-shaped structure behind the reflected shock and vortex formation. This was visualised through numerical shadowgraph images and by tracing the streamlines in the flow field. A study on the variation in temperature is carried out in order to have a quantitative assessment. It was found that the temperature inside the mushroom structure is higher than that behind the reflected shock. The study of species mass fraction in this region is also made. The flow inside the mushroom structure was found to be a reactive mixture of gas slug.
