A Reynolds-Averaged Navier-Stokes (RANS) numerical method has been employed m conjunction with a chmrera domam decomposition approach for the prediction of hydrodynamic drag and lift forces of submerged and floating sea caches under combmed wave and current effects. The method was employed recently to evaluate the performance of three different sea cache configurations of rectangular, sharp-edged, and round-edged shapes under strong ocean currents and the round-edged sea cache was found to provide the most desirable overall hydrodynamic performance. In the present study, the method was further extended for time-domain simulation of round-edged sea cache configuration under combined actions of ambient wave and ocean current. The sea cache may be floating on the free surface, or tethered at mid-height, and the ocean current may approach the sea cache m the same or opposite direction of the incoming wave field. Detailed velocity, pressure, and wave patterns were obtained to determme the hydrodynamic characteristics of the sea caches. The drag and lift forces were also computed to evaluate the combined wave and current effects on the sea caches.
The present study addresses some of the hydrodynamic issues relevant to the operation of a modular, submersible pontoon system (Sea Cache) in littoral water. Knowledge about environmental loads as well as seakeeping characteristics of pontoon based submersible structures in littoral water is limited. The primary objective of the present study is to develop a numerical method in support of the design efforts providing pontoon structures with the integrity, stability, and maneuverability required to operate in littoral environments. The sea caches may be moored on the surface as platforms for access by helicopters, anchored on the ocean floor for covert activity from below, or tethered for operation at any intermediate depth.
