流体力学--aps审核

EngineeringFluidMechanicsAtthebeginningofthiscourse,theteacherintroducedsomebasicdefinitions,suchasthecompressibility压缩性(weusethecompressioncoefficienttodenotethecompressibility,itmeansweremainthetemperatureconstantly,asweincreasingthepressure,thecorrespondingamountofincreasingvolumeofeachunit.P3),theexpansibility膨胀性(thesame)andtheviscosity粘性（toexplaintheviscosity,wemustconcernNewtoninnerfrictionlaw:wecaneducetheNewtoninnerfrictionfunctionfromthisfunction(图P5),itmeansthepullforceisproportionaltovelocityofBandthecontactarea,inverselyproportionaltothedistanceorheight.Ifthechangeofvelocityisnotlinear,isnonlinear,wecantakedifferentialtoexpressthefriction,itmeansthefluidinnerfrictionisrelativetothepropertyoffluid,proportionaltothevelocitygradient速度梯度）.Thisfunctionisverybasicbutusefulforthecontentwelearntlater.Vector(矢量)coordinates(坐标系)projection(投影)Ithinkthiscoursecanbedividedtotwoparts:thehydrostaticsandhydrodynamics.InthehydrostaticspartthemostbasicandrepresentativecontentistheEulerequation(P14),itdenotestherelationshipofmassforce(质量力theforceactingoneachfluidmassparticle)，density(密度)andpressuregradient(压力梯度).Inthehydrodynamicspart,IthinkthemostimportantandrepresentativecontentistheBernoulliequation(P67).TheBernoulliequationiseducedfromtheEulermotionequation,buthassomerestrictions,forexamplethefluidcan’tbecompressedandwithgravityactingonit.Alsowecancomprehendthisequationfromphysicalaspect.Ithasaphysicalmeaningthatthemechanicenergyofthefluidisconservation(流体机械能守恒).Ithinkthismeaningiseasytocomprehend.