The 12th International Conference on Hydrodynamics
18 – 23 september 2016, Egmond aan Zee, The Netherlands
10:30   Multiphase Flow
Chair: Marcelo Neves
10:30
30 mins
EVOLUTION OF A SPILLING BREAKER: AN EXPERIMENTAL STUDY OF THE GEOMETRICAL AND KINEMATIC FEATURES.
Alessia Lucarelli, Massimo Falchi, Mario Felli, Claudio Lugni, Giuseppina Colicchio, Maurizio Brocchini
Abstract: We here describe an experimental study of a spilling breaker finalized to the comprehension of the physics and on the development of a simplified mathematical model for the motion of the breaker. Such a model is based on the three-layer structure already proposed by the authors:: an underlying potential flow, a thin, turbulent single-phase layer in the middle and a turbulent two-phase layer (air-water) on the upper part. Laboratory experiments have been specifically designed and carried out to investigate the physical mechanisms involved in the interaction among the mentioned three layers. A sloshing wave has been selected for the generation of the breaker. A 3m long, 0.6m deep and 0.10m wide tank has been built in Plexiglas and forced through an hexapode system, which allows a high accuracy of the motion. To ensure repeatability of the phenomenon, a suitable breaker event has been generated to occur during the first two oscillation cycles of the tank. The tank motion has been suitably designed using a potential and a Navier-Stokes solver. A PIV system has been set-up to measure both mean and turbulent kinematic quantities. The analysis of the experimental data will provide information on possible links of the geometrical quantities that characterize the individual layers, and the kinematic quantities measurable in the single-phase turbulent layer.
11:00
30 mins
NUMERICAL STUDY OF IMPACT FORCE OF HIGH SPEED WATER-ENTRY BODIES
YAO HONG, Benlong Wang, Hua Liu
Abstract: ABSTRACT The water-entry of 2D bodies at high impact velocities is studied numerically in this article. The flow model treats the fluid as a compressible mixture of air and water with homogeneous material properties, with the understanding that one or the other of the two constituents is essentially absent in the bulk of the domain. A high-resolution, the Godunov-type method, is employed to solve the governing equations numerically. The fluid flow around a water-entry body is assumed to be inviscid. The gravity effect can be ignored because of the short period of time for the early stage of water entry process. A set of numerical experiments for a water-entry body with different velocities are studied. It turns out that the impact force is found to increase with the velocity as expected. To validate the accuracy of the mixture method, we compare the computed results with the experiment data available. Good agreements between them are obtained.
11:30
30 mins
HYDRODYNAMICS OF A MUDDY ESTUARINE ENVIRONMENT: SUMMERTIME VS WINTERTIME CONDITIONS
Maurizio Brocchini, Joseph Calantoni, Matteo Postacchini, Allen Reed, Carlo Lorenzoni, Alessandro Mancinelli
Abstract: The hydrodynamics of an estuarine environment characterized by cohesive sediments, has been studied through a pair of experimental campaigns performed at the mouth of the Misa River. The Misa River flows from the Apennine Mountains and enters the Adriatic Sea in Senigallia, a tourist town located on the Mid-East coast of Italy. The estuary of the Misa River has characteristics of a field-scale laboratory; the final reach is highly engineered with containment structures. Consequently, it was chosen as a suitable site for the experiments undertaken during the EsCoSed (“Estuarine Cohesive Sediment”) Project. The estuarine environment of the Misa River was observed during both summertime and wintertime experiments. The hydrodynamics was monitored using both Eulerian (e.g., bottom moored platforms at both the river-bed and sea-bed with high-resolution ADCPs recording velocity profiles) and Lagrangian (e.g., surface drifters) instrumentation, allowing for the characterization of the flow field during very different flow conditions. The climate occurring before and during the investigated periods has also been analyzed through use of numerical simulations, wave buoy measurements, and tide gauges. A comparative analysis between summertime and wintertime conditions, focused on wave-current forcing and local estuarine hydrodynamics, is underway. The preliminary results highlight the control of wind direction on the observed hydrodynamics. During the summertime the wind frequently changes direction. Conversely, during wintertime the wind direction remains fairly constant leading to severe storms. The extreme wintertime events generate intense sediment transport driving morphologic change.