Improvement of Suspended Sediment Transport Analysis Considering the Spatial Influence of Turbulence Ejection and Sweep Events

The structural properties of turbulent boundary layers have been the subject of many investigations. Over the last decades, a large number of investigators have demonstrated that turbulent boundary layers are populated by a hierarchy of recurrent structures, normally referred as 'coherent structures'. Recent work by Eisma et al. (2015) confirmed the existence of internal interfaces of strong shear in the turbulent region of the boundary layer. Thereafter, de Silva et al. (2017) began with a description of a detection criterion which was utilized previously to locate uniform momentum zones (UMZ) and showed how this criterion can be employed to estimate the spatial location of the edges that demarcate UMZs. Further, under the computation of all conditionally averaged statistical properties in the near vicinity of these UMZ edges, i.e. Conditional wall-normal profiles of streamwise velocity Û , wall-normal velocity Ŵ and wall-normal gradient of the streamwise velocity ∂Û /∂Z, revealing a scenario of Q2 (Û<0, Ŵ>0 ) events below UMZ edges and Q4 (Û>0, Ŵ<0 ) events above UMZ edges.

Motivated by these previous studies and inspired by Tsai et al. (2019), we aim at examining the influence of two flow structures, called the ejection and sweep events, in the near-wall region on suspended sediment transport. In an attempt to deduce how the characterization of UMZs in the turbulent boundary layers, such as the streamwise momentum deficit ,and occurrences of Q2 events and Q4 events in the near vicinity of UMZ edges, under different Reynolds numbers would impact sediment particle trajectory, a refined stochastic particle-tracking model is proposed.

REFERENCES

EISMA, J., WESTERWEEL, J., OOMS, G. & ELSINGA, G. E. 2015 Interfaces and internal layers in a turbulent boundary layer. Phys. Fluids 27 (5), 055103.

DE SILVA , C. M. , PHILIP , J. , HUTCHINS , N. & MARUSIC I. 2017 Interfaces of uniform momentum zones in turbulent boundary layers . J. Fluid Mech. 820 , 451 - 478 .

TSAI, C. W. & HUANG S.-H. 2019 Modeling Suspended Sediment Transport Under Influence of Turbulence Ejection and Sweep Events. Water Resour. Res., 55.