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Unformatted text preview: Lecture 20 Fluid dynamics, Bernoulli's Equation Fluid flow Laminar flow : no mixing between layers Turbulent flow : a mess… Dry water, wet water Real (wet) fluid: friction with walls and between layers (viscosity) Slower near the walls Faster in the center Ideal (dry) fluid: no friction (no viscosity) Same speed everywhere Within the case of laminar flow: Flow rate Consider a laminar, steady flow of an ideal, incompressible fluid at speed v though a tube of crosssectional area A Volume flow rate Δ V Δ t = Av A Δ V = Av Δ t v Δ t Mass flow rate Δ m Δ t = ρ Av Continuity equation A 1 A 2 v 1 v 2 The mass flow rate must be the same at any point along the tube (otherwise, fluid would be accumulating or disappearing somewhere) If fluid is incompressible (constant density): ρ 1 ρ 2 A 1 v 1 = A 2 v 2 Volume flow rate is constant Conservation of mass: ρ A 1 v 1 = ρ 2 A 2 v 2 Example: Garden hose When you use your garden faucet to fill your 3 gallon watering can, it takes 15 seconds. You attach this faucet to your 1.5 cm thick garden hose fitted with a nozzle with 10 holes at the end. Each of the holes is 0.48mm in diameter....
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 Summer '08
 B
 Fluid Dynamics, Friction, volume flow rate, Bernouilli

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