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Learn about pressure distribution, centroid, and center of pressure on surfaces exposed to fluids. Explore examples with plywood forms, concrete, and gates in this elementary fluid mechanics guide.
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Elementary Mechanics of Fluids CE 319 F Daene McKinney Hydrostatic Forces on Plane Surfaces
F Centroid Center of pressure Pressure on Plane Surface Surfaces exposed to fluids experience a force due to the pressure distribution in the fluid
Plywood Form (2.44m x 1.22m) Concrete (23.6 kN/m3) 2.44 m F Example
F Centroid Center of pressure Line of Action of Force • Lies below centroid, since pressure increases with depth
T F Example (3.59) • F as H ? • as H ? • is constant as H ? • T as H ? • T is constant as H ?
0.133 Fw,g 2 Fb,g Example (3.73) Find: Force of block on gate F
RA 6 3-0.4641 F Example (3.78)
Air G 5.01 ft 18 ft Water A Oil SG=0.75 gate 6 ft B Example Given: Gate AB is 4 ft wide, hinged at A. Gage G reads -2.17 psi Find: Horizontal force at B to hold gate. Solution: Convert negative pressure in tank to ft of water
A Air G 5.01 ft 3.03 ft 4ft 18 ft Fw Water Foil A FB Oil SG=0.75 gate 6 ft B B Example