Fluid Mechanics and Fluid Transport
This domain covers fluid statics and dynamics, pipe flow, pumps and compressors. Master: viscosity and Newtonian vs non-Newtonian behavior; Reynolds number and its regimes; the Bernoulli equation and its limitations (steady, incompressible, inviscid, along a streamline); the mechanical energy balance with friction losses; Darcy-Weisbach and friction factor (Moody chart, Colebrook equation); minor losses (K factors, equivalent length); pump curves, system curves, NPSH and cavitation; and flow measurement (orifice, venturi, rotameter).
Traps: applying Bernoulli across a pump or with significant friction; confusing volumetric and mass flow; forgetting that NPSH_available must exceed NPSH_required to avoid cavitation; and mixing laminar (f = 64/Re) with turbulent friction correlations. Questions about pipe diameter changes often hinge on continuity (A₁v₁ = A₂v₂) rather than Bernoulli alone.
Worked example (rule of thumb): Re = ρvD/μ = 4ṁ/(πDμ). Laminar if Re < 2100, turbulent if Re > 4000. For turbulent flow, use the Moody chart or Colebrook: 1/√f = −2 log[(ε/D)/3.7 + 2.51/(Re√f)]. For a quick estimate, f ≈ 0.02–0.03 for commercial steel pipe at high Re.