Wavelet analysis on the turbulent flow structure of a T-junction

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades

“…The flow rate of the branch duct was measured by a glass rotameter, and the uncertainty of the bulk branch velocity was ±4.3%. More details on the experimental setup have been published in Yin et al [ 20 ] and Su et al [ 6 ].…”

“…The error due to the spatial resolution is maximized at only 13% at y /L = 0.0070, then sharply reduces to 6% at y /L = 0.014. Therefore, it could be thought that the error is systematic due to the same hot-wire probe, and this does not adversely affect the results near the T-junction [ 6 ]. The inaccuracy because of the blockage effects can be negligible for values larger than 20 wall units, and the minimum in our study is 76, so the effect of blockage can be negligible [ 27 ].…”

“…It is a complex-valued wavelet and can provide not only phase information, but also amplitude information. Furthermore, it has a good local balance in both the time and frequency domains [ 6 ], so the Morlet wavelet was used in the processing of CWT in this study. Its definition is: where ω 0 is the dimensionless frequency and here taken to be ω 0 = 6 following the recommendations of Torrence et al [ 37 ].…”

“…The velocity ratio, which is the ratio of the suction velocity of ventilation to the velocity of the train, was proposed to ensure similar flow patterns. More details about the physical model of T-junction have been reported by Su et al [ 6 ].…”

“…As the Reynolds number increases, the size of the coherent structure is bigger. Su et al [ 6 ] studied multi-resolution coherent structures in T-junctions without blades, but they did not eliminate the edge-effect of the CWT. In fact, there are typically blades in the vents of the train to prevent waste from entering the train cabin.…”