Mostfluidflowsinnatureandengineeringapplicationsareinthestateofturbulence.Turbulentmotionsusuallyexhibitawiderangeofspatialandtemporalscales,suchastheflowofnaturalgasandoilinpipelines,thewakesofcarsandsubmarines,theboundarylayerofanaircraft,thecurrentintheoceansurface,theatmosphericboundarylayer,theinterstellargasclouds(gaseousstars),andtheEarth’swakeinthesolarwind.Turbulencecangreatlyimprovetheheatandmasstransferefficiencyofmacroscopicflow.Forexample,chemicalengineersuseturbulencetomixupandhomogenizefluidcomponentsandtoincreasechemicalreactionratesinliquidsorgases.However,turbulencecanalsoleadtoincreasesindrag,aerodynamicheat,andhydrodynamicandaerodynamicnoise.Forinstance,theaerodynamicloadingofhigh-speedaircraftcanbesignificantlyincreasedduetoturbulence.
