Abstract
The purpose of this paper is to clarify the effects of helical strakes around a serrated-fin tube on the vortex shedding. It was made clear that Karman vortex was clearly formed even in the case of a fin tube with helical strakes. The existence of helical strakes around a fin tube caused the decrease of the vortex shedding frequency and the increase of the periodicity of vortex shedding from a fin tube. The coherent scale of vortex in the spanwise direction is larger in the case with helical strakes compared with that of a serrated fin tube.
