Chapter.5Fluid Mechanics
Chapter 5 Fluid Mechanics
$1.Ideal fluidl-1 Definition Fluid Statics(density) and pWe consider the relation between P (pressure).We should establish an simple model①p=constantincompressible（△visnegligible)samein solidNoviscous force“dryfluidNo shearing stress like the pressure in static fluid"P is independent of the“orientation of area "", butdepend on the position and velocity (when it flows)
§1. Ideal fluid 1-1 Definition Fluid Statics We consider the relation between (density) and P (pressure). We should establish an simple model: v =constant incompressible ( is negligible ) same in solid No viscous force “dry fluid”. No shearing stress like the pressure in “static fluid”. P is independent of the “ orientation of area ” , but depend on the position and velocity (when it flows). P
1-2 Streamline and stream tubuleFlow field V = v(x, y,z)Curve: tangential line indicate the direction of like “electric line of force""For any point , y is uniqueStream tubeNo crossNoflow through
1-2 Streamline and stream tubule v = v(x, y,z) v Flow field Curve: tangential line like “electric line of force”. indicate the direction of For any point , is unique. Stream tube: v No cross. No flow through.
1-3 Steady flow and unsteady flowSteady flow = v(x, y,z) path lineUnsteady flowstream lineds1-4 Fluid fluxdv=vcosdsdtdm = pvcos dsdt
v = v(x, y,z) 1-3 Steady flow and unsteady flow Unsteady flow stream line path line Steady flow 1-4 Fluid flux dv = v cos dsdt dm = v cos dsdt n v ds
Volume flux: dQ, = vcosOds = ·dsMass flux:dQm = pvcosOds = pv·dsI = pe,vdcurrentFinite surfaceOm=JdOm=JpvdsSimilar:of Ed(s)(S)Φβ=[BdQ,= [dQ, = [vds(s)(s)
dQ v ds v ds v = cos = dQ v ds v ds m = cos = I en vd = = = (s) (s) v v Q dQ vds = = (s) (s) m m Q dQ vds Volume flux: Mass flux: current Finite surface Similar: E = Ed B = Bd