Kev sib txhuam vs viscosity
Kev txhuam thiab viscosity yog ob yam khoom ntawm cov teeb meem, uas yog qhov tseem ceeb hauv kev nkag siab txog tus cwj pwm ntawm cov teeb meem. Nws yog ib qho tsim nyog yuav tsum muaj kev nkag siab zoo ntawm viscosity thiab ntom kom piav qhia txog feem ntau ntawm cov xwm txheej tshwm sim hauv cov dej dynamics, kua dej statics, khoom statics, khoom dynamics, thiab yuav luag txhua txhua daim ntawv thov engineering. Cov phenomena no tau pom nyob rau hauv niaj hnub lub neej, thiab yog yooj yim to taub, muab hais tias, txoj kev yog coj. Hauv tsab xov xwm no, peb yuav tham txog qhov kev sib txhuam thiab viscosity yog dab tsi, lawv cov lus txhais, qhov sib xws, dab tsi ua rau kev sib txhuam thiab viscosity, thiab thaum kawg lawv qhov sib txawv.
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 units ntawm viscosity yog Pascal-thib ob (los yog 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. Nws tuaj yeem pom meej meej tias viscosity ib txwm ua nyob rau hauv ib qho kev taw qhia, los tawm tsam cov dej ntws. Lub zog viscous raug faib thoob plaws hauv lub ntim ntawm cov kua hauv ib qho kev mob dynamic.
Kev sib tw
Kev sib txhuam yog tej zaum qhov kev tawm tsam ntau tshaj peb tau ntsib txhua hnub. Kev sib txhuam yog tshwm sim los ntawm kev sib cuag ntawm ob qhov chaw ntxhib. Kev sib txhuam muaj tsib hom; Kev sib txhuam qhuav uas tshwm sim ntawm ob lub cev, kev sib txhuam ntawm cov kua dej, uas tseem hu ua viscosity, lubricated kev sib txhuam, qhov twg ob lub khib nyiab sib cais los ntawm cov kua txheej, cov tawv nqaij sib txhuam, uas tawm tsam cov khoom txav hauv cov kua, thiab cov kev sib txhuam sab hauv uas ua rau cov khoom sib txawv. Internal Cheebtsam ntawm ib qho khoom ua kom muaj kev sib txhuam. Txawm li cas los xij, lo lus "kev sib txhuam" feem ntau yog siv los ntawm kev sib txhuam qhuav. Qhov no yog tshwm sim los ntawm cov kab noj hniav ntxhib microscopic ntawm txhua qhov chaw haum rau ib leeg thiab tsis kam txav mus los. Qhov kev sib txhuam qhuav ntawm ob qhov chaw nyob ntawm qhov sib txhuam coefficient thiab lub zog reactive ib txwm rau lub dav hlau ua rau ntawm cov khoom. Qhov siab tshaj plaws kev sib txhuam zoo li qub ntawm ob qhov chaw tsuas yog siab dua qhov kev sib txhuam dynamic.
Dab tsi yog qhov sib txawv ntawm Friction thiab Viscosity?
• Viscosity yog, qhov tseeb, ib pawg ntawm kev sib txhuam, txawm li cas los xij, kev sib txhuam qhuav tsuas yog tshwm sim ntawm ob qhov chaw, thaum viscosity tshwm sim hauv cov kua nruab nrab ntawm ob txheej ntawm cov kua.
• Cov xwm txheej zoo li qub thiab zoo li qub tau txhais nyias rau kev sib txhuam qhuav. Rau viscosity, tsis muaj qhov zoo li qub vim tias cov kua molecules yog ib txwm mobile.
