Horizontal pressure gradient and bed shear stress under double dam-break driven swash and validation of a Reynolds-Averaged Navier-Stokes equations based model

Swash zone processes drive foreshore morphodynamics through sediment transport gradients. Sediment transport rates are often estimated using bed shear stress as the main hydrodynamic driver. However, the importance of pressure gradients relative to bed shear stress in the swash zone is still poorly known. Thus, it is important to investigate the importance between pressure gradients and bed shear stress as a function of cross-shore distance, swash phase and interaction intensity. ☐ A double dam-break mechanism was used to produce near prototype swash events and allowed for analysis of swash interactions. The time offset between the bore propagation varied (0 s to 3 s) to investigate swash interactions. The impermeable immobile bed roughness was varied between a smooth bed (d50 = 0.166 cm) and rough bed (d50 = 3.05 cm) on a fixed slope to see the effect on foreshore hydrodynamics. A total of 14 different cases were analyzed with the goal of collecting 10 repetitions for each case. The laboratory experiments collected in-situ data of depth, velocity, and pressure over a swash event. The hydrodynamic data for each case were ensemble averaged and verified a numerical model solving the two-dimensional (2D) Reynolds-Averaged Navier-Stokes (RANS) equations simulating a double dam break. The model allows for visualization of the hydrodynamic data over the entire domain and is used to identify the type of swash interactions occurring for each case. ☐ Mobilization parameters such as the Mobility parameter, Shields parameter, Sleath parameter, and a combined parameter were analyzed to quantitatively describe the probability for hypothetical sediment to move based on different forcing mechanisms.

Grantor dc:publisher

University of Delaware

Year dc:date.issued

2022

Author dc:creator

• Olney, Courtney

• Bed shear stress
• Dam-break
• Horizontal pressure gradient
• Numerical model

DOI

https://doi.org/10.58088/tcbe-mf85

OAI identifier oai:identifier

oai:udspace.udel.edu:19716/32292