The effect of “regularly spaced twisted tape” on heat transfer of high Prandtl number fluid flow was investigated using Large Eddy Simulation. This tape has a pair of a swirl region with twisted tape and an intermittent region with tape-connecting rod. In each swirl region, there is a gap between inner pipe wall and twisted tape. It was found that appropriate width gap can generate the suck back in the gap. The mixing of near gap region is enhanced and the local Nusselt number near the gap becomes high. Consequently, the mixing of whole fluid can be further promoted in the intermittent region.
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