rade control structures are used to control bed erosion in steep small rivers mostly in the mountains. scour downstream of this structure can lead to failure. over the past years, the effect of different variables on this phenomena have been studied, however the effect of upward seepage which is common due to head difference of the banks water table or water surface level between the upstream a...

Sea otters (Enhydra lutris) are keystone predators that consume a variety of benthic invertebrates, including the intertidal mussel, Mytilus californianus. By virtue of their competitive dominance, large size, and longevity, M. californianus are ecosystem engineers that form structurally complex beds that provide habitat for diverse invertebrate communities. We investigated whether otters affec...

A three-dimensional numerical model is used to compute the water flow field in a straight flume with a cobble bed. The geometry of the numerical model is a replication of a physical model experiment where the largest cobbles were approximately 10 cm long. Detailed information on the digital terrain model of the bed was available from a laser scan of the bed. In the experiments, flow velocity pr...

Submarine pipelines are appropriate method for transmission of oil and gas from sea bed. Free spans may occur due to the natural uneven seabed or by under-scouring. Vortex Induced Vibration (VIV) can happen in such free spans at high Reynolds number. Resonance occurs if the frequency of vortex shedding is close to the pipeline’s natural frequency leading to its fatigue that can break the pipeli...

In this paper, we characterize the filtration and deposition profiles of a recombinant analog of Norwalk virus, an important waterborne pathogen, in packed beds of saturated quartz sand under both ‘clean-bed’ and ‘dirty-bed’ conditions. Under clean-bed conditions with NaCl as the electrolyte, the retained Norwalk virus particles decline like a power-law with depth. The power-law decay in retain...

The effect of foaming on the performance of 16 mm Pall rings was determined in a 0.15 m distillation column with a ‘bed depth of 1.23 m. The tests were conducted with the methanol/water system at 1.0 bar pressure. A controllable foaming inside the packed bed was generated successfully with the addition of the surfactant, Triton X-100, to the reflux stream. The performance of the packing with an...

We show that a freshly sedimented bed composed of spherical grains settles and creeps forward over extended periods under an applied hydrodynamic shear stress τ∗, which is below the critical value τ∗ c for bedload transport. The rearrangements are found to last at least over millions of times the sedimentation time scale of a grain in the fluid. Compaction occurs throughout the bed, but creep i...