Note on Water Drag on Sea Ice for Different Surface Roughness

The approach in Myrhau

Curiosity driven search: When is relevance irrelevant?

Classical information search behaviour models based on work-task scenarios fail to explain common leisure search scenarios motivated by a hedonistic need rather than a defined information need. This paper presents work into such unstructured search driven by curiosity. In order to explore this hedonistic catalyst, a social media search application was designed in which the search experience is triggered by the user's spatio-temporal context during their exploration rather than query-response based information retrieval. We report a study with real users and a simulated casual-leisure search task where results indicated that relevance is not relevant for some searches

Time scales for scour below pipelines and around vertical piles due to nonlinear random waves

This paper provides a practical stochastic method by which the time scale for the equilibrium scour depth below pipelines and around slender vertical piles exposed to long-crested (2D) and short-crested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall (2000) wave crest height distribution representing both 2D and 3D nonlinear random waves. Moreover, the time scale for regular waves given by Sumer and Fredsøe (2002) are used. Examples of results are also presented

Effect of bottom roughness on sediment transport due to streaming beneath linear propagating waves with an angle of attack on current

The effect of bottom roughness on sediment transport due to three-dimensional wave-induced streaming in the seabed boundary layer has been investigated for following and opposing linear propagating waves and current where the wave propagation forms a non-zero angle with the current. Visualizations are given by mean Eulerian wave-averaged suspended flux profiles, as well as the time series of bed shear stress over a wave period. The bedload transport rate along with suspended flux and total sediment transport rate have been presented. For linear propagating waves, the turbulence is induced by the Longuet-Higgins streaming and the classical wave-current interaction. Sediment transport is always in the wave propagation direction for the Longuet-Higgins streaming and increases with decreasing bottom roughness, or as the mean grain diameter decreases

Scour below marine pipelines due to random waves on mild slopes

This paper provides a practical stochastic method by which the maximum equilibrium scour depth beneath a marine pipeline exposed to random waves on mild slopes can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Battjes and Groenendijk (2000) wave height distribution for mild slopes including the effect of breaking waves, and using the empirical formulas for the scour depth on the horizontal seabed by Sumer and Fredsøe (1996). Results will be presented and discussed by varying the seabed slope and water depth. An approximate method is also proposed, and comparisons are made with the present stochastic method. Generally, it appears that the approximate method can replace the stochastic method

Some probabilistic properties of surf parameter

This article is supplementary to Myrhaug (2018) and presents some probabilistic properties of the surf parameter for individual waves and the spectral surf parameter for sea states by using distributions based on data from the Norwegian continental shelf. The average statistical features given by the mean value and the standard deviation of the two surf parameters are considered. Examples of results for the surf parameter are provided for a Phillips spectrum and a family of JONSWAP spectra for wind sea, and for sea states using a joint frequency table of significant wave height and mean zero-crossing wave period for combined wind sea and swell. The spectral surf parameter results are obtained by using a joint distribution of significant wave height and spectral surf parameter, and the mean statistical properties are given for joint frequency tables of significant wave height and mean zero-crossing wave period from three deep water locations on the Norwegian continental shelf. It is also demonstrated how the results can be applied to calculate the vertical wave runup elevation for breaking waves