Fluid Effects > Set Initial State > 
With the Set Initial State Options window, you can set the contents of a fluid’s initial state. The contents checked on in the Set Initial State Options window are set in the initial state. By default, all initial state content options are on.
The initial state of a fluid is created from the dynamic or static grid contents. When setting the initial state, if a content method has dynamic or static grid attributes but is not checked in the Set Initial State Options window, a warning appears and you are prompted to either include the grid attributes or omit them from the cache.