Layer-averaged numerical study on effect of Reynolds number on turbidity currents

ABSTRACT

Direct numerical simulations of lock-exchange turbidity currents with small Reynolds number were often assumed to well represent turbidity currents with large Reynolds number. Here, this assumption is examined using a layer-averaged numerical model. It is shown that in the initial stage the current front position converges if the Reynolds number approaches certain threshold values. However, at later stages, turbidity currents with larger Reynolds number propagate faster and farther. This is because, by definition, a larger Reynolds number corresponds to more sediment mass carried by the current, and thus higher driving force. Furthermore, turbidity currents with the same Reynolds number can correspond to very different front positions and deposition profiles, as the Reynolds number depends on both current thickness and concentration.

Keywords:

• Current front position
• direct numerical simulation
• layer-averaged modelling
• Reynolds number
• turbidity currents

Additional information

Funding

This research is supported by the National Natural Science Foundation of China (numbers 11772300, 11872332), the Zhejiang Provincial Natural Science Foundation (LR19E090002), and the HPC Center OF ZJU (ZHOUSHAN CAMPUS); National Key Research and Development Program of China (2017YFC0405400).