Viscosity vs Kinematic Viscosity | Dynamic Viscosity, Absolute Viscosity
Viscosity yog qhov tseem ceeb heev uas tau tham hauv cov tshuab ua kua. Viscosity thiab kinematic viscosity muaj ntau yam kev siv hauv thaj chaw xws li dej dynamics, dej mechanics, aerodynamics, chemistry thiab txawm tias kev kho mob science. Kev nkag siab zoo hauv cov ntsiab lus ntawm viscosity thiab kinematic viscosity yuav tsum tau ua kom tau zoo hauv cov lus hais saum toj no. Hauv tsab xov xwm no, peb yuav tham txog dab tsi viscosity thiab kinematic viscosity yog, lawv cov ntsiab lus, kev siv viscosity thiab kinematic viscosity, qhov zoo sib xws thiab thaum kawg qhov sib txawv ntawm kinematic viscosity thiab viscosity.
Viscosity
Viscosity txhais tau tias yog qhov ntsuas ntawm qhov tsis kam ntawm cov kua dej, uas yog deformed los ntawm kev ntxhov siab los yog tensile stress. Hauv ntau lo lus, viscosity yog "kev sib txhuam sab hauv" ntawm cov kua dej. Nws tseem hu ua lub thickness ntawm cov kua. Viscosity tsuas yog kev sib txhuam ntawm ob txheej ntawm cov kua dej thaum ob txheej txav mus rau ib leeg. Sir Isaac Newton yog ib tug pioneer hauv dej mechanics. Nws postulated tias, rau ib tug Newtonian kua, lub shear kev nyuaj siab ntawm cov khaubncaws sab nraud povtseg yog proportional rau lub ceev gradient nyob rau hauv cov kev taw qhia perpendicular mus rau lub txheej. Qhov proportional tas li (proportionality factor) siv ntawm no yog viscosity ntawm cov kua. Lub viscosity feem ntau txhais los ntawm Greek tsab ntawv "µ". Viscosity ntawm cov kua tuaj yeem ntsuas tau siv Viscometers thiab Rheometers. Cov chav nyob ntawm viscosity yog Pascal-thib ob lossis Nm-2s. Lub cgs system siv chav tsev "poise", npe tom qab Jean Louis Marie Poiseuille, los ntsuas viscosity. Viscosity ntawm cov kua kuj tuaj yeem ntsuas los ntawm ntau qhov kev sim. Lub viscosity ntawm cov kua yog nyob ntawm qhov kub thiab txias. Lub viscosity txo qis raws li qhov kub thiab txias.
τ=μ (∂u/∂y)
Viscosity sib npaug thiab cov qauv yog qhov nyuaj heev rau cov kua dej uas tsis yog Newtonian. Muaj ob lub ntsiab ntawm viscosity. Lawv yog cov dynamic viscosity thiab kinematic viscosity. Dynamic viscosity tseem hu ua qhov viscosity kiag li. Dynamic viscosity yog qhov kev ntsuas viscosity dav siv hauv feem ntau ntawm kev suav. Qhov no txhais tau tias yog µ lossis ɳ. SI unit ntawm dynamic viscosity yog Pascal vib nas this. Yog tias cov kua dej uas muaj viscosity ntawm 1 Pascal vib nas this tau muab tso rau ntawm ob daim hlau thiab ib lub phaj raug thawb mus rau sab nrog ib qho kev nyuaj siab ntawm 1 Pascal, nws txav deb ntawm qhov sib npaug ntawm cov thickness ntawm cov phaj hauv 1 thib ob.
Kinematic Viscosity
Qee zaum, lub zog inertial ntawm cov kua kuj tseem ceeb rau kev ntsuas viscosity. Lub zog inertial ntawm cov kua yog nyob ntawm qhov ntom ntawm cov kua. Yog li ntawd, ib lo lus tshiab hu ua kinematic viscosity yog txhais, los pab xws li kev suav. Lub kinematic viscosity yog txhais raws li qhov piv ntawm cov dynamic viscosity rau qhov ntom ntawm cov kua. Lub kinematic viscosity raug xa mus los ntawm lo lus ν (Greek tsab ntawv nu). Kinematic viscosity muaj units ntawm meters squared muab faib los ntawm vib nas this. Chav tsev stoke kuj yog siv los ntsuas qhov kinematic viscosity.
Qhov txawv ntawm Viscosity thiab Kinematic Viscosity yog dab tsi?
• Lub sij hawm viscosity feem ntau yog hais txog ob qho tib si viscosity thiab kinematic viscosity.
• Dynamic viscosity yog ywj siab ntawm qhov ntom ntawm cov kua, tab sis kinematic viscosity nyob ntawm qhov ntom ntawm cov kua.
• Kinematic viscosity yog sib npaug rau dynamic viscosity faib los ntawm qhov ntom ntawm cov kua.
