开边界如何设置？

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请问开边界是指有水与无水的边界吗？它与动边界有什么区别？如何处理呢？
是不是要计算当前水流到哪个网格，然后指定它为开边界，再用相应的公式计算呢？
请各位大侠指点！

legolasGG

请问开边界是指有水与无水的边界吗？
Excuse me that I can';t input chinese.
No, open boundary is due to the fact that general ocean or harbor is much bigger than the computer can handle, so we have to confine the domain of computation, the boundary that is connected to water domain not computed is called open boundary.
On the other hand, the boundary that connects water and no water(air) is not open boundary, it';s rather called free surface boundary, typically kinematic conditions and zero pressure conditions are applied.

它与动边界有什么区别？
Moving bounday is a general concept, any boundary that is moving can be called moving boundary. For example, free surface boundary can be moving boudary if the free surface is moving. The boundary between ship bottom and water is moving boundary if the ship is moving.
  In tidal or water waves simulation, a special moving boundary is the interface between the water and the coastal beach, waves/tides run up and down the beach, that area is called swash zone and relatively hard to simulate.
如何处理呢？
  For swash zone moving boundary. Some people use slots method, some use wet-dry method, some use an artificial film layer on the beach.
  For open boundary, you need to use one of the following 1)sommerfeld radiative boundary 2) some kind of absorbing boundary such as ';sponge layer';  3)periodic boundary  4)specify values on open boundary from measurements.
  
是不是要计算当前水流到哪个网格，然后指定它为开边界，再用相应的公式计算呢？
请各位大侠指点！
   
  

browser

多谢！多谢，受益匪浅！