Structured by the official ETEC subject standard for this topic: every listed topic and learning outcome, with formulas, figures and worked examples. The full sections are available to members in the app.
SKU 4.1 · Fluid properties
Density, viscosity and Newton’s law of viscosity
What makes a substance a fluid, the mass properties (density, specific weight, specific gravity) and viscosity, the property that resists sliding.
Ideal, real, Newtonian and non-Newtonian fluids
How fluids are classified by the way they resist shear, with the models used for each class and how to tell them apart from test data.
Compressibility, surface tension and vapour pressure
Bulk modulus and the speed of sound, capillary rise, and why a liquid boils when its pressure drops to the vapour pressure (cavitation).
Fluid power: hydraulic and pneumatic basics
How a pressurised liquid or gas carries energy from a pump to an actuator: Pascal’s law, power as pressure times flow, and why oil and air behave so differently.
SKU 4.2 · Fluid statics and dynamics
Hydrostatic pressure and its measurement
Why pressure in a fluid at rest grows with depth and nothing else, absolute and gauge pressure, and how manometers turn a column height into a pressure.
Forces on submerged plane and curved surfaces
The resultant hydrostatic force on gates, walls and tank sides, where it acts (centre of pressure), and the two-component method for curved surfaces.
Buoyancy and stability of floating bodies
Archimedes’ principle, the fraction of a floating body that is submerged, and the metacentric height that decides whether a ship rights itself or capsizes.
Describing a flow: kinematics and flow types
Eulerian and Lagrangian views, steady and uniform flow, streamlines, pathlines and streaklines, and the acceleration of a fluid particle in a velocity field.
Systems, control volumes and conservation of mass
The three conservation laws, why fluid problems use a control volume rather than a system, the Reynolds transport theorem that links them, and the continuity equation.
Differential analysis: continuity and Navier–Stokes
The conservation laws written at a point: the differential continuity equation, the meaning of each term of the Navier–Stokes equation, and exact one-dimensional solutions between plates.
Bernoulli’s equation and flow measurement
The trade between pressure, speed and height along a streamline, its strict assumptions, and the venturi meter, orifice plate and Pitot tube built on it.
The momentum equation: jets, vanes and pipe bends
The integral momentum equation from the Reynolds transport theorem, and the forces it gives on plates and vanes struck by jets, on pipe bends and nozzles, and the thrust of a jet.
Internal flow: laminar and turbulent pipe flow
The Reynolds number and the two regimes of pipe flow, entrance length, the parabolic and turbulent velocity profiles, Hagen–Poiseuille flow and the hydraulic diameter of non-circular ducts.
Major losses: pipe friction and the Moody chart
The Darcy–Weisbach equation, reading the friction factor from the Moody chart or Colebrook equation, the three types of pipe problem, and pipes in series and parallel.
Minor losses and pipe-system energy balance
Loss coefficients of entrances, exits, expansions, bends and valves, the energy equation with pump and turbine heads, energy and hydraulic grade lines, and sizing a pump.
External flow: boundary layers, drag and lift
How a boundary layer grows on a surface, why it separates, the two parts of drag, drag and lift coefficients, and Stokes’ law for very slow flow.
Dimensional analysis and similitude
The Buckingham Π theorem, the dimensionless groups of fluid mechanics and what each compares, and how to scale a model test to the full-size machine.
Compressible flow: Mach number, isentropic flow and normal shocks
When density changes matter, stagnation properties, why a nozzle must converge then diverge to go supersonic, choking, and the jump across a normal shock.
Hydraulic components, pumps and their selection
What each part of a hydraulic power unit does, how positive-displacement pumps deliver flow, their volumetric, mechanical and overall efficiencies, and how to choose a pump or compressor.
Pneumatic system components
From the compressor to the cylinder: air production, treatment, storage and distribution, and how to estimate a cylinder’s free-air consumption.
Control valves and fluid-power symbols
Directional, pressure and flow control valves, how they are drawn in ISO 1219-1 symbols, and how to read a valve symbol and size a flow-control orifice.
Hydraulic and pneumatic actuators: sizing and performance
Force and speed of cylinders on extension and retraction, the regenerative connection, torque and speed of hydraulic motors, and sizing a cylinder for a load.
Basic hydraulic and pneumatic circuits and sequencing
The standard circuits for one actuator, speed control, regenerative and unloading circuits, the pneumatic logic valves, and how multi-actuator sequences are written and solved.
Fluid-power distribution and circuit design
Sizing lines from flow velocity, pressure loss and heat in lines, overall circuit efficiency, and a worked design of a press circuit from load to motor.
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