Performance Study of Spiral Finned Tubes on Heat Transfer and Wake Flow Structure

•We propose a way how to identify turbulent coherent structure around the helical finned tube by Q criterion.•This work aims to find the coherent structures around spiral fins using the Q-criteria .•The dynamic mode decomposition is used to illustrate the relationship between the heat transfer coefficient and the turbulent flow structure.•The work quantitatively analyses the tendency of vortex structure variation around finned tubes by the value of Q criterion, the change of molecular rotation energy and deformation energy with time.•The results based on the newly developed boundary condition show a good agreement with other existing results.