Evaluation of Seakeeping Predictions

Analysis and algebraic­symbolic determination of conditions forsafe motion of a vessel in a non­stationary environment

“…In accordance with [9], the research undertaken over last decades has addressed integrated methods that would work well in two dimensions. In this case, there were difficulties in extending the accuracy of research results to three dimensions, especially under conditions of turbulence.…”

“…While a vessel sails the sea in stormy weather, its hull is exposed to various negative dynamic factors of wave influence. These include: resonance in pitching, position of the vessel on two edges of waves, turbulence zone, impacts from particularly large waves, as well as shoving waves that emerge during exposure to multiple wave systems (wind, swell, different directions of waves [3,4,9,11,19,21,25].…”

“…That is why at the second stage of enabling the adaptation of objects to environmental perturbations we must have time dimensions -evaluation of random field of sea waves. The prediction is made easier by the fact that time μ and spatial K frequencies of the same spectral components of sea waves are related via a dispersion relation 2 , gK m = (9) where g is the acceleration of gravity. If we managed to obtain for certain time t a two-dimensional spatial implementation of upheavals in wave relief z(x, y, t), then we shall perform a two-dimensional Fourier transform for the obtained implementation of a wave relief in the form of the sum of all flat spectral components ( , , ) (11) We shall change in time the components of phase .…”

“…First, when the degree of danger is within tolerance ε, then the law of control U(t, X, W), Х is the vector of parame-ters of the state of controlled movable object, W is the vector of threats of factors EAE, corresponds to the stabilization modes of internal parameters of the vessel and kinematic monitoring relative to the planned motion route on the navigating water area [6,7]. This is a normal long mode for a safe navigation area (SNA) at operation with EAE noises [8][9][10][11][12][13].…”

Energy-efficient large medium-speed catamarans: Hull form design by full-scale CFD simulations

“…Resolving the boundary layer flow with y + = 1, where the velocity increases linearly with increasing distance from the wall, would require a relatively small first cell height that results in a very fine boundary layer mesh for flows at high Reynolds numbers. It can be shown that y 1 scales with Re −0.93 which leads to a first cell height of 1,000 times finer at log(Re) = 9.75 compared to log(Re) = 6.5, which would increase the computational resource requirements and may cause numerical issues due to high aspect ratio cells (Stern et al, 2013). However, when using wall functions, the first cell height has to reach into the boundary layer where a logarithmic velocity applies.…”