RIASSUNTO
Abstract
Numerical predictions given by the Neumann-Michell linear-potentialflow theory have previously been reported and found to be in good overall agreement with experimental measurements of the drag, the sinkage and the trim experienced by a number of monohull ships, as well as the wave profiles along the ship hulls, within a range of (relatively low) Froude numbers. The Neumann-Michell theory has also been widely used for ship hull-form optimization, and found to be a robust practical method useful for design. For further validation, the theory is applied here to two catamarans. Numerical predictions and experimental measurements of the free-surface elevation along a longitudinal cut, the drag, the sinkage and the trim are found to be in good overall agreement for both the ‘Delft catamaran model’ and the ‘Series 60 catamaran model’, with (nondimensional) lateral distances s = S/L between the twin hulls of the catamarans equal to 0.167, 0.233, 0.300 (Delft) or 0.226, 0.307, 0.388 (Series 60), within the relatively wide ranges of high Froude numbers 0.3 ≤ F≤ 0.8 (Delft) or 0.3 ≤F ≤ 0.55 (Series 60). The Neumann-Michell theory is also used to compute the wave patterns of the Delft catamaran and the Series 60 catamaran at Froude numbers 0.3 ≤F ≤ 1.2. These computations show that, at high Froude numbers, the largest waves created by the catamarans are found inside the cusp lines of the Kelvin wake due to wave-interference effects, as previously explained by the authors.