IV. The coefficient of viscosity of air

doi:10.1098/rspl.1886.0008

IV. The coefficient of viscosity of air

Proceedings of the Royal Society of London ◽

10.1098/rspl.1886.0008 ◽

1886 ◽

Vol 40 (242-245) ◽

pp. 40-42 ◽

Cited By ~ 2

Keyword(s):

Internal Friction ◽

Torsional Vibrations ◽

Coefficient Of Viscosity ◽

Cylinders And Spheres

The author has had occasion, whilst investigating the internal friction of metals, to determine the coefficient of viscosity of air. The viscosity of air has already engaged the attention of several distinguished experimenters, amongst others, of G. G. Stokes, Meyer, and Clerk Maxwell. The results obtained, however, differ so widely that it was considered necessary to institute fresh researches into the same subject. The author employed the torsional vibrations of cylinders and spheres, suspended vertically from a horizontal cylindrical bar, and oscillating in a sufficiently unconfined space.

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I. The influence of stress and strain on the physical properties of matter. Part I. Elasticity— continued . The internal friction of metals

Proceedings of the Royal Society of London ◽

10.1098/rspl.1886.0028 ◽

1886 ◽

Vol 40 (242-245) ◽

pp. 240-242

Keyword(s):

Internal Friction ◽

Physical Properties ◽

Stress And Strain ◽

Vibrating Wire ◽

Coefficient Of Viscosity ◽

Molecular Friction

An abstract of a paper on this subject has been already published, but the paper itself was withdrawn for the purpose of revision. The fresh experiments which have been for this purpose instituted during the last year were made with improved apparatus, and the coefficient of viscosity of air redetermined, with a view of enabling the author to make more accurate correction for the effect of the resistance of the air. These more recent experiments on the loss of energy of a torsionally vibrating wire, besides confirming the results of the older ones, as far as the latter have been published, have furnished, more or less in addition, the following facts relating to the internal molecular friction of metals.

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XIX. The coefficient of viscosity of air

Philosophical Transactions of the Royal Society of London ◽

10.1098/rstl.1886.0020 ◽

1886 ◽

Vol 177 ◽

pp. 767-799 ◽

Cited By ~ 8

Keyword(s):

Internal Friction ◽

Tangential Force ◽

Absolute Temperature ◽

Spare Time ◽

The Coefficient Of Friction ◽

The Many ◽

Coefficient Of Viscosity ◽

Lower Plane ◽

Different Parts

Origin and Purpose of the Investigation . Three years ago I entered on a series of researches relating to the internal friction of metals, little calculating, when I did so, that the task which I had set myself would occupy almost the whole of my spare time from that date to this. So, however, it has been, and one of the many causes of delay has been the necessity of making a re-determination of the coefficient of viscosity of air; for the resistance of the air played far too important a part in my investigations to permit of its being either neglected or even roughly estimated. The coefficient of viscosity of air may, according to Maxwell, be best defined by considering a stratum of air between two parallel horizontal planes of indefinite extent, at a distance r from one another. Suppose the upper plane to be set in motion in a horizontal direction with a velocity of v centimetres per second, and to continue in motion till the air in the different parts of the stratum has taken up its final velocity, then the velocity of the air will increase uniformly as we pass from the lower plane to the upper. If the air in contact with the planes has the same velocity as the planes themselves, then the velocity will increase v/r centimetres per second for every centimetre we ascend. The friction between any two contiguous strata of air will then be equal to that between either surface and the air in contact with it. Suppose that this friction is equal to a tangential force f on every square centimetre, then f = μ v/r , where μ , is the coefficient of friction. If L, M, T represent the units of length, mass, and time, the dimensions of μ are L -1 MT -1 . Several investigators have attempted to determine the coefficient of viscosity of air, and the following table shows how very widely the results obtained differ among each other :— Further, Maxwell finds the coefficient of viscosity of air to be independent of the pressure and to vary directly as the absolute temperature. The above author gives the following formula for finding fit the coefficient of viscosity, at any temperature θ ° C.:— μ = .0001878(1 + .00365 θ ).

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Internal friction in certain tidal currents

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1929.0103 ◽

1929 ◽

Vol 124 (793) ◽

pp. 150-163 ◽

Cited By ~ 3

Keyword(s):

Internal Friction ◽

Turbulent Motion ◽

Viscous Forces ◽

Frictional Forces ◽

Kinematic Coefficient ◽

The Subject ◽

North Polar ◽

Coefficient Of Viscosity ◽

Hydrodynamical Theory

1. In the application of hydrodynamical theory to the motion of the water in the sea or ocean it has long been desirable to obtain some measure of the internal friction. Most writers on the subject have considered this to be equivalent to the determination of a "virtual kinematic coefficient of viscosity" ( k ), taken to represent the combined effect of molecular viscosity and eddy viscosity, and which was supposed to play a part in turbulent motion analogous to that of ordinary viscosity in non-turbulent motion, except that k might vary from place to place. The validity of this supposition has, however, recently been questioned. The importance of a knowledge of the internal friction was realised in 1902, when Nansen published the results of the Norwegian North Polar Expedition of 1893-96. Subsequently methods for the determination of k were proposed, the majority of which, however, involve the assumption that at a particular place k may be considered to be independent of the depth. The only tidal work on the subject is due to J. Proudman and J. H. Powell. At the present time, however, no laws are known for the accurate prescription of the internal frictional forces, they are certainly not the simply viscous forces of non-turbulent motion.

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