Page 14 - ebook fluid mechanics_finalize

FLUID MECHANICS

1.1.2 Describe the Characteristics of Fluid

Material Molecular Structure/Characteristics

Solid
• The molecules can be fictitiously linked each other with springs.

• Fix shape.

• Elastic (return to original shape when stress is removed).
• Stress proportional to strain.

• Molecules can move freely but are constrained through a traction force
called cohesion which is interchangeable from each other.
Liquid
• On the surface to cohesion forms a resultant force directed into the liquid
region.

• The combination of cohesion forces between adjacent molecules from a

tensioned membrane known as free surface.
• Occupies a fixed volume and will take the shape of the container

• Stress proportional to rate of shear stress strain

Gas

• No definite shape.
• No definite volume

• All molecules move freely in any direction fill up its container

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