Mike11 ---08---溃坝模拟一般设置

发布于新浪博客，时间：2009-02-19 21:59:51 原文 (opens new window)

溃坝结构物可以看作是两个独立的结构物组成，即宽顶堰及溃口。在Mike11里两块单独计算，溃口处流体的计算方法有两种，一是Mike11 Energy Eq，一是NWS DAMBRK Eq。设置坝的基本参数，溃坝前顶高程Crest Level，溃坝前坝的长度Crest Length；设置溃坝条件，可以是开始模拟多少时间后开始溃（Failure moment --- hours after start 该选项指在模拟开始时间之后多少开始溃坝，0->开始1个小时后，依次类推）、确定的某个日期时间开始溃、或水库水位达到设定的某一值时溃；

A dambreak structure is a composite structure composed of a structure representing the flow over the crest (Crest flow structure) and another structure representing the breach of the dam.

• Mike11 Energy Eq

溃口为等腰梯形渐变，须设置三个边界条件即，随时间变化的等腰梯形的的下底高程、下底宽及边坡，做成dfs0文件在边界编辑器里引入，切记ID的对应输入。若已知时间序列的梯形渐变，则模型计算时按时间内插，若未知，则只须初始化三个参数即可。

溃口由冲蚀模型计算

• NWS DAMBRK

Breach failure，采用堰近似方程来计算；Piping failure ，管涌近似方程来计算。二者都须在边界编辑器里指定一个溃口渐变文件，包含溃口底高/底宽/边坡大小。如果是后者还需提供溃口顶高。

Time Step Control，用于改变溃坝后的计算步长（只增加）。It is recommended to use an adaptive time step as an alternative to this feature.

在进行溃坝模拟之前，建议作一个热启动文件，作为溃坝模拟的初始场。

In many cases dam failures occur on a dry river bed downstream. However, such initial conditions should be treated with caution in MIKE 11. Hence, before a dambreak is actually simulated, it is expedient to create a steady-state 'hot start' file which can be used for all subsequent dambreak simulations.

制作热启动文件：在坝后第一个h计算点加入一小的入流；水库的入流非零；坝不溃，计算的水位大于库水位。做稳态模拟，如果结果文件太大，则可以通过以此结果文件为热启动文件减少模拟步数重新做一次模拟产生小的热启动文件。

With the hot start file ready, the dambreak simulation can now be carried out. It is suggested that a DELTA value of slightly more than the default of 0.5 be used to damp out short waves which may lead to numerical instabilities.

A time step of the order 1-10 minutes is suggested.