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The Froude number is based on the speed–length ratio which he defined as: [2] [3] = where u is the local flow velocity (in m/s), g is the local gravity field (in m/s 2), and L is a characteristic length (in m). The Froude number has some analogy with the Mach number.
In conclusion, by choosing a scale of 1:25 for the lengths and by complying with Froude's law, the engineers at Sogreah – Port Revel built models 25 times smaller, operating 5 times more slowly, but as the distances are 25 times less, things occur 5 times faster. The ships are 78 125 times less powerful.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Froude's method tends to overestimate the power for very large ships. [1] Froude had observed that when a ship or model was at its so-called Hull speed the wave pattern of the transverse waves (the waves along the hull) have a wavelength equal to the length of the waterline. This means that the ship's bow was riding on one wave crest and so was ...
William Froude (/ ˈ f r uː d /; [1] 28 November 1810 in Devon [2] – 4 May 1879 in Simonstown, Cape Colony) was an English engineer, hydrodynamicist and naval architect.He was the first to formulate reliable laws for the resistance that water offers to ships (such as the hull speed equation) and for predicting their stability.
He validated his theoretical models with extensive empirical testing, using scale models for the different hull dimensions. He established a formula (now known as the Froude number) by which the results of small-scale tests could be used to predict the behaviour of full-sized hulls. He built a sequence of 3, 6 and (shown in the picture) 12 foot ...
In physics, a characteristic length is an important dimension that defines the scale of a physical system. Often, such a length is used as an input to a formula in order to predict some characteristics of the system, and it is usually required by the construction of a dimensionless quantity, in the general framework of dimensional analysis and in particular applications such as fluid mechanics.
I can't decide whether to add a section on Froude's Law here or create a new (small) page. Perhaps a more experienced Wikipedian will know what to do. Here is a start on the content: Froude's law states that the velocity of a water-born creature or craft is proportional to the square root of it length. Reference: Thompson, D W., 1992.