The Norwegian North Polar Expedition, 1893-1896; Scientific Results Volume 5

The Norwegian North Polar Expedition, 1893-1896; Scientific Results Volume 5

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...resistance and the frictional resistance cannot be quite independent of each other, and the method should consequently not be allowed; but the experiments seem to show--as might be expected a priori--that it is practically correct. 1 This artifice may often be of use in solving problems concerning the motion of the water-layers in the sea. See White's 'Manual', p. 479 seq. It may be pointed out that the two rules above, hold approximately even if the whole resistance be considered. For the frictional resistance varies approximately as the wetted area of the vessel and as the square of the velocity, so that it is obvious it will vary approximately according to the two rules given. The eddy-making resistance is of smaller importance; the same rules hold true for it, provided the motions are really "similar," because it is a resultant of pressure. It could not, however, be taken into account when deducing the rules, because it should not exist at all in a frictionless fluid. Besides the viscosity, we must also take account of the capillary forces, which influence the small scale experiments more strongly than those on a full scale, and thus disturb the similarity. On the one hand, these forces prevent the creation of ordinary surface waves in the experiments; on account of capillarity these waves cannot move with a velocity slower than 20 or 23 cm. per second, and the boat-models were towed at still smaller velocities. This effect of capillarity is, however, of no importance, because, at the slow speeds at which dead-water occurs, even full-sized ships do not produce any appreciable surface-waves. The secondary waves in the surface which are produced by the boundary-waves, are--on account of their greater length--not appreciably influenced...
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Product details

  • Paperback | 94 pages
  • 189 x 246 x 5mm | 181g
  • United States
  • English
  • black & white illustrations
  • 1236493621
  • 9781236493620