Abstract
The long distance pneumatic conduit conveyance of so-called multiphase fluids has recently been attempted in the field of marine construction works and coastal zone developments. This system is very useful for conduit transport on fluidity materials. So far studies have been focused on the onset and periodic mechanisms on slugging in a mixture of air. This paper mainly describe about passage period of slug flow in long pipeline. As the result of this investigation, it was to clarify that the passage period of air-water two-phase flow was controlled by air -water ratio.