Advanced features of modern CFD codes, such as Volume Of Fluid, moving mesh and Overset grid techniques have made it possible to simulate extreme waves and their interaction with fixed and floating structures, to provide essential design information such as wave run up, air gap, green water, wave impact loading and hull motion. Recent developments in far-field closure techniques such as the Euler Overlay Method (EOM) reduces the size of the CFD domain, to make it possible to obtain extreme responses of a floater in waves with the same accuracy of the physical model test, hence to utilize the numerical wave basin in floater design.
Technip recently used the EOM-based numerical wave basin in designing new hull form for the dry-tree Semisubmersible for deep- and ultra-deep water development. Global performances of prototype hulls in several design sea states are simulated in the EOM-based numerical wave basin and are validated against the physical model test data. The validated numerical wave basin set-up, such as mesh size, time step and input waves, is applied to the global performance simulation of a new hull form as a part of the design spiral for optimizing performance relative to the initial prototype. The simulation results are also utilized to calibrate conventional global performance analysis tools based on potential theory and Morison equation.
Examples of global performance validation and hull form optimization will be presented. How and which direction the involvement of numerical wave basin within the design spiral will change the design process of offshore floater will be discussed based on those examples.