Supported by Ritsumeikan University's International Research Promotion

Seminar on Simulation of Coastal Processes
Tricea I 2F Seminar Room 1 (Just facing elevator)

Tuesday Nov 24, 2015

Ritsumeikan Univ., BKC Campus, Kusatsu

10:00 -12:20

10:00 – 10:45 Eiji Masunaga (Tokyo University of Marine Science and Technology)"Internal tidal dynamics in the vicinity of Izu-Oshima Island investigated by numerical simulations."
Abstract: Internal waves significantly contribute to transport e.g. heat, salt, energy, sediment andorganic materials in the ocean. Continental shelves and shallow coastal areas are known as “hot spot” ofinternal tide generation site. However, generation processes and dynamics of internal tides have not been
understood well. This study presents physical processes associated with internal tides around Izu-OshimaIsland investigated by a numerical ocean model, SUNTANS. Although semidiurnal surface tides
dominate in sea-surface tidal elevations, diurnal internal tidal energy would be much stronger thansemidiurnal tide when the topography tends to enhance Kelvin trapped internal waves.

10:45–11:30

Matt Rayson(University of Western Australia)"Challenges in three-dimensional hydrodynamic modelling of the shallow bays and estuaries along
the Gulf of Mexico coast"
Abstract: The Gulf of Mexico coast is characterized by wide, shallow bays and estuaries with narrow
openings to the Gulf and geometrically complex shorelines. Tidal forcing is small (< 0.5 m range) yet
strong tidal currents (>1.0 m s-1) with large spatial variability exist at narrow constrictions and shipping
channels. I will first present validation of hydrodynamic modeling results from Galveston Bay, Texas,
using the 3D finite-volume SUNTANS model with hybrid quadrilateral/triangular grids. I will thenapply the validated hydrodynamic model to understand the transport time scales and salinity variability
within this unsteady estuarine system, notably those associated with transient flooding and storm events.

11:35-12:20

Yusuke Uchiyama (Kobe University)"Three-dimensional modeling of time-dependent wave-driven currents on a sandy beach "Abstract: Alongshore shear instability associated with longshore currents driven by obliquely
incident waves, and offshore-directed rip currents under a near-normal incident wave condition are
analyzed with the ROMS-WEC model (Uchiyama et al., 2010). The coupled wave-current model
successfully reproduces 3-D shear waves during the Sandy Duck field measurement. Rip
current-induced coherent eddies (surf eddies) are generated ubiquitously on a surveyed beach
topography, having significant depth-dependency that leads to faster decay of enstrophy and kinetic
energy than 2-D surf eddies. VLFs (very low frequency motions) are excited with a steady wave
forcing either with the 3-D or 2-D models. The feedback mechanism of current effects on wave(CEW) is found to be essential to impel the VLF-EKE (eddy kinetic energy) shoreward. Alongshore
irregularity in the beach topography is responsible for enhancing the shore-confined VLF-EKE
substantially.
contact; Prof. John C. Wells, Dept. Civil Eng, Ritsumeikan Univ.

jwells@se.ritsumei.ac.jp tel. 080 6148 7010