Pressure drop depends on velocity, diameter, length and roughness.
Flow in pipes is driven by pressure drop to overcome wall friction. Laminar: ΔP=128μLQ/(πD⁴), so flow varies with D⁴. Turbulent requires empirical friction factors. Entry length L_e≈0.06 Re D (laminar). Design balances pipe size against pumping cost.
Halving diameter in laminar flow cuts flow by 16 at the same pressure drop.
Pipe flow pressure drop determines pump size and energy use, so it is central to water, oil and gas distribution design.
Pressure drop depends on velocity, diameter, length and roughness.
Pipe flow pressure drop determines pump size and energy use, so it is central to water, oil and gas distribution design.
Velocity, diameter, length, roughness and fluid properties, with the pressure drop rising with the square of velocity.
Velocity rises for the same flow, so friction losses grow rapidly, which increases pumping power.
Typical applications include sizing a pump for a water main that serves a village, choosing a pipe diameter that keeps pressure loss acceptable and estimating the flow rate that a given pressure difference can deliver.
Study "Reynolds number" first (topic 57 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Fully developed flow. Roughness effects. Economic diameter.
Halving diameter in laminar flow cuts flow by 16 at the same pressure drop.
The next topic is "Darcy-Weisbach equation", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 58 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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