Computational Methods Applied to Some Diverse Topics in Marine Engineering

To solve relevant problems within the area of practical marine engineering of industrial interest, efficient and accurate numerical methods are required. Furthermore, an adequate physical description of the wave environment leads to complex models of the relevant time-varying processes. This results in significant challenges both with respect to the modeling techniques and the corresponding analysis of marine vehicles, installations, and operations. As a reflection of the growing importance of computational methods in marine engineering, Marine 2009, the Third International Conference on Computational Methods in Marine Engineering, was held in Trondheim, Norway. Seventy-nine papers covering a broad range of topics were presented. The applications included multiscale modeling, coupled problems, ship hydrodynamics, and structural mechanics. A wide range of numerical techniques were applied, including boundary-element, finite-element, finite-difference, and finite-calculus methods.

Four presentations from that conference have been expanded into journal technical papers for this focus issue. These papers involve emerging areas in coastal and ocean engineering, such as the development of aquaculture facilities and offshore wind turbines, as well as relatively new techniques such as the finite calculus and the solution of ill-posed inverse problems by application of Tikhonov regularization in combination with Bayesian methods. In addition to the four technical papers, there are four additional papers that are not directly related to the conference.

Of the four papers emerging from the conference, the first one, “Simulation of Water Circulation over a Model of a Submarine Canyon by Using FIC-FEM Numerical Model” by German et al., is concerned with numerical simulation of the detailed flow field around a local 3D topographic feature. The focus is on efficient numerical algorithms to reduce the computational efforts, and the finite calculus-finite element method is used. The finite calculus (FIC) procedure is based on writing the momentum and mass balance equations over a domain of finite size and retaining the higher-order terms. The resulting stabilized numerical solution scheme, coupled with the use of finite element discretization of the spatial domain, allows greater flexibility in relation to the numerical model, especially when dealing with the complex geometry of irregular coastlines and seabeds.

The second paper, “Ocean Current Inference Using Towed Cable Hydrodynamics” by Polydorides and Storteig, deals with estimation of multiple parameters for the case that the number of measured quantities is less than the number of unknown quantities (i.e. an ill-posed problem). Combination of the prior information with the information obtained from the measurements by means of Bayesian techniques is outlined. Also for this case, numerically efficient procedures are in focus.

The third paper, “Wave- and Wind-Induced Dynamic Response of Spar-Type Offshore Wind Turbine” by Karimirad and Moan, involves numerical aero-hydro-servo-elastic time-domain simulations of dynamic response in the time-domain. The loading is of a complex nature since it is attributable to a combination of the current, wave, and wind environmental processes. Furthermore, the response exhibits highly nonlinear features. Accordingly, the accuracy and efficiency of the computational schemes are of key importance. The paper contains results of importance to this growing industry.

The fourth paper, “Statistical Analysis of Stress Histories for Fatigue Damage Design of Floating Fish Cages” by Thomassen and Leira, is also concerned with nonlinear load and structural effects within the context of a time-domain response analysis. For the type of structure being considered, it is found that the interaction between the load and response process creates highly nonlinear phenomena. This implies limitations associated with the length of the time steps that can be applied in the response analysis. Accordingly, the resulting computational efficiency also comes into focus since a range of different wave conditions needs to be analyzed in relation to estimation of fatigue damage.

All papers were subjected to anonymous peer review following the usual review standards and procedures of the journal. We thank the reviewers for their hard work.