Level 3 Engineering Principles - Fluid Systems Equations Sheet

1. LEVEL 3 ENGINEERING PRINCIPLES – FLUID SYSTEMS EQUATIONS Hydrostatics Equations Subject Equation Variables and Units ρ =m ρ = density in kilograms per cubic meter (kg/m3) Fluid Density V m = mass in kilograms (kg) ρ V = volume in cubic meters (m3) RD = Relative Density ρ? RD = relative density (dimensionless) ρw = density of water in kilograms per cubic meter (kg/m3) Hydrostatic Pressure P = ρgh P = hydrostatic pressure / pressure head in Pascals (Pa) g = gravity in meters per second squared (m/s2) F = ρghA Hydrostatic Force h = fluid depth in meters (m) F = thrust force in Newtons (N) M =ρgℎ?A Overturning Moment A = area of surface subjected to water pressure in meters squared (m2) 3 Tubes, Pipes and Ducts Subject Equation Variables and Units Q = volume flow rate in cubic meters per second (m3/s) Q = vA Volume Flow Rate v = fluid velocity in meters per second (m/s) A = cross sectional area of pipe or duct in meters squared (m2) v?A?= v?A? m ̇ = mass flow rate in kilograms per second (kg/s) m ̇ = ρQ ρ = density in kilograms per cubic meter (kg/m3) Mass Flow Rate