Department of Civil Engineering
Ph.D. Student, Civil Engineering, Stony Brook University
Monday, November 24, 11:00AM – 12:00PM, Frey Hall 313
Coastal and riverine communities face escalating risks from compound flooding, driven by climate change, sea-level rise, and intensifying storm events. Floodborne debris, sourced from diverse origins such as tree logs, lumber, rocks, boats, and structural fragments, significantly amplifies these risks by obstructing waterways, damaging coastal defenses, and compromising critical infrastructure. The transport of different debris types is influenced by complex flow hydrodynamics and diverse bathymetric features in coastal and riverine systems, yet current debris impact models oversimplify these dynamics. This study presents a combined experimental and SPH-based investigation of debris entrainment, transport modes, and its consequent impact loading over varying bathymetric features. A large-scale experimental campaign—135 trials using two smart debris models—captured 6DOF debris motions, hydrodynamic forces, and debris–structure impact sequences under both smooth and abrupt slope–berm transition conditions. Debris motions were tracked using smart debris and computer vision methods, while hydrodynamic and impact loads on an instrumented structure were measured via a multi-axis load cell. Results show distinct pickup and transport processes governed by impoundment depth, submergence ratio, debris orientation, and downstream placement. There are three key transport regimes: leading-edge riding, bore-front transport, and lagging motion, each producing different impact mechanisms including impulsive, buffered, successive, and 3D rotational impacts due to surrounding flow cushioning effects. Secondary impacts—often overlooked in design codes—were shown to significantly influence structural demand, especially when debris rotation is amplified by abrupt bathymetric changes. Complementary SPH simulations (DualSPHysics + Chrono) reproduced debris trajectories and impact kinematics with high agreement, enabling parametric exploration of density effects and bore–debris–bed interactions. Findings emphasize the controlling role of surface-roller cushioning, debris-bottom contact, and flow–structure feedback in determining impact severity, offering critical insights for the design and resilience assessment of coastal and hydraulic structures exposed to floodborne debris.
Mohammadreza received his Bachelor’s degree in Civil Engineering and his Master of Science degree in Coastal and Marine Structures Engineering, both from the University of Tehran, Tehran, Iran, and he focused on a numerical investigation of fluid-structure-interaction for partially perforated caissons. He is currently pursuing his Ph.D. in the Civil Engineering Department at Stony Brook University. He is a research assistant in the Coastal and Hydraulic Engineering Research Laboratory (CHERL) of Dr. Ali Farhadzadeh. Mohammadreza is currently working on coastal resiliency, focusing on quantifying flood-borne debris motion, impacts, and the resulting damage to coastal structures.