Ambient Entrainment Mechanisms of Partially Unconfined Turbidity Currents Interacting with a Continuous Rigid Obstacle

In this study, the entrainment mechanisms of unconfined turbidity currents that interact with a linear rectangular obstacle will be investigated and compared with confined studies. Laboratory experiments will be performed in a lock exchange basin, where the width allows unconfined and partially unconfined flows, with varying initial current densities. Ambient fluid entrainment, based on the Morton-Taylor-Turner (MTT) hypothesis, was found to be comparable to previous confined studies; however, in situ current density decreased at a greater rate than the latter. It was shown that this was probably caused by the unconfined lateral spreading of the current before the obstacle. The entrainment parameter had a weak relationship with Froude, Reynolds, and Richardson numbers for nonobstructed tests, which was similar to previous studies. However, this was not the case for obstacle tests, which experienced a greater variance in entrainment velocity and head height. Of note, head height was less than that for equivalent confined tests, which suggested that in a practical setting, confined studies might overestimate the obstacle height needed to block current propagation.

Automated summary

This study investigates the entrainment mechanisms of unconfined turbidity currents interacting with linear rectangular obstacles and compares them with confined studies. The results show that lateral spreading of unconfined currents before obstacles leads to a greater rate of decrease in current density compared to confined conditions. Additionally, obstacle tests exhibit a larger variance in entrainment velocity and head height, with the head height being lower than that for equivalent confined tests.