March 01, 2016, HFH 4164

The wave buoy analogy is a tested means for shipboard sea state estimation. Basically, the estimation principle resembles that of a traditional wave rider buoy, where transfer functions, used torelate measured wave‐induced responses and the unknown wave excitation, are fundamental. This talk addresses however a newly developed concept of the wave buoy analogy, not relying exclusively on transfer functions. Instead, the method combines a signal‐based part, estimating wave frequency, and a model‐based part, estimating wave amplitude and phase, where only the model‐based part depends on transfer functions whereas the signal‐based part relies on the measured vessel response alone. Case studies in terms of numerical simulations and model‐scale experiments show that the method is capable of reconstructing fully the wave elevation process of a regular wave; which includes estimation of the wave's frequency, amplitude and phase, respectively. At this stage, the method is far from being a useful means in practical, real‐situation applications but the method provides, indeed, a valuable step towards developing new approaches for shipboard sea state estimation.

In 2005, Ulrik Dam Nielsen obtained his Ph.D. degree from the Section of Coastal, Maritime and Structural Engineering at DTU Mechanical Engineering. After four years as Post Doc. and assistant professor at DTU, Ulrik joined, in 2009, the faculty of DTU Mechanical Engineering as an associate professor. Research and teaching is primarily about wave-ship interactions with a main focus on onboard monitoring and decision support systems for safe and efficient marine operations. In the research, several topics are addressed, including analysis of full-scale measurements, in-situ estimation of the sea state at the location of an advancing vessel, fatigue damage accumulation in the hull girder, numerical models for the prediction of ship responses.
Ulrik is a board member of the Danish Society of Naval Architecture and Marine Engineering and is currently chairman of the Standing Committee of the International Symposium of Practical Design of Ships and Other Floating Structures (PRADS), which will be organised in Copenhagen in September 2016.