Page 27 - ebook fluid mechanics_finalize

FLUID MECHANICS

Thus weight density of liquid = S x Weight density of water, water

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= S x 1000 x 9.81 N/m

The density of a liquid = S x Density of water, ρwater

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= S x 1000 kg/m . …..(1.1a)

If the specific gravity, S of a fluid is known, then the density of the fluid will be

equal to specific gravity of fluid multiplied by the density of water.

[Example : the specific gravity of mercury is 13.6, hence the density of mercury,

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ρmercury = 13.6 x 1000 = 13600 kg/m .]

2.2.4 Specific volume.

Specific volume, v is defined as the reciprocal of mass density. It is used to mean

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volume per unit mass and SI units, m /kg.

1 volume, V
 =  =
 OR mass, m

2.2.5 Viscosity.

Viscosity,  (called meu) is defined as the property of a fluid, due to cohesion and

interaction between molecules, which offers resistance to shear deformation. Different

fluids deform at different rates under the same shear stress. The ease with which a fluid
pours is an indication of its viscosity. Fluid with a high viscosity such as syrup deforms

more slowly than fluid with a low viscosity such as water. The viscosity is also known as

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-3
dynamic viscosity. Units: Ns/m or kg/ms Typical values: Water = 1.14x10 kg/ms; Air
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= 1.78x10 kg/ms

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