Kinematic viscosity yog ib qho tseem ceeb ntawm lub cev yam ntxwv ntawm tag nrho cov pa roj thiab kua xov xwm. Qhov ntsuas no yog qhov tseem ceeb hauv kev txiav txim siab ntawm kev txav ntawm lub cev thiab cov khoom thauj uas lawv tau ntsib. Raws li koj paub, hauv peb lub ntiaj teb, txhua qhov kev txav mus los tshwm sim hauv huab cua lossis dej ib puag ncig. Hauv qhov no, lub cev txav mus ib txwm cuam tshuam los ntawm lub zog uas nws vector yog qhov sib txawv ntawm qhov kev taw qhia ntawm kev txav ntawm cov khoom lawv tus kheej. Raws li, qhov ntau dua qhov kinematic viscosity ntawm nruab nrab, qhov muaj zog ntawm cov khoom tau ntsib los ntawm cov khoom. Dab tsi ntawm cov cuab yeej ntawm cov kua thiab roj no yog dab tsi?
Kinematic viscosity, txhais tau tias yog kev sib txhuam sab hauv, yog vim qhov hloov pauv ntawm cov tshuaj molecules perpendicular mus rau kev taw qhia ntawm kev txav ntawm nws cov khaubncaws sab nraud povtseg nrog ceev sib txawv. Piv txwv li, nyob rau hauv cov kua, txhua yam ntawm cov structural units (molecule) yog nyob ib ncig ntawm tag nrho cov sab los ntawm nws cov neeg nyob ze, nyob ze ntawm ib tug deb sib npaug zos rau lawv txoj kab uas hla. Txhua lub molecule oscillates nyob ib ncig ntawm ib qho kev sib npaug ntawm txoj hauj lwm, tab sis, siv lub zog los ntawm nws cov neeg nyob ze, nws ua rau dhia mus rau qhov chaw tshiab ntawm oscillation. Hauv ib thib ob, txhua chav tsev ntawm cov teeb meem no muaj sij hawm los hloov nws qhov chaw nyob txog ib puas lab lub sij hawm, ua rau ntawm jumps ntawm ib mus rau pua pua txhiab oscillations. Tau kawg, qhov muaj zog xws li molecular kev sib cuam tshuam, qis dua yuav yog qhov txav ntawm txhua chav tsev thiab, raws li, qhov ntau dua qhov kinematic viscosity ntawm cov khoom.
Yog tias ib qho molecule raug ua los ntawm cov quab yuam sab nraud los ntawm cov khaubncaws sab nraud povtseg, ces nyob rau hauv cov kev taw qhia no cov particle ua ntau displacements ib chav tsev ntawm lub sij hawm tshaj nyob rau hauv lub opposite direction. Yog li ntawd, nws chaotic wandering yog hloov mus rau hauv ib qho kev txiav txim txav nrog ib tug tej yam ceev, nyob ntawm seb lub zog ua rau nws. Qhov viscosity no yog ib txwm, piv txwv li, ntawm cov roj cav. Ntawm no, qhov tseeb hais tias sab nraud quab yuam siv rau cov particle nyob rau hauv kev txiav txim siab ua haujlwm ntawm ib hom kev thawb sib nrug ntawm cov khaubncaws sab nraud povtseg los ntawm qhov muab molecule squeezes kuj tseem ceeb. Xws li qhov cuam tshuam thaum kawg ua rau qhov nrawm ntawm thermal random motion ntawm hais, uas tsis hloov nrog lub sijhawm. Hauv lwm lo lus, cov kua dej yog tus cwj pwm los ntawm kev sib txawv, txawm hais tias muaj kev cuam tshuam tas mus li ntawm ntau qhov chaw sab nraud, vim tias lawv sib npaug los ntawm kev tiv thaiv sab hauv ntawm cov txheej txheem, uas tsuas yog txiav txim siab coefficient ntawm kinematic viscosity.
Nrog rau qhov kub thiab txias, kev txav ntawm cov molecules pib nce, uas ua rau qee qhov txo qis hauv qhov tsis kam ntawm cov khaubncaws sab nraud povtseg ntawm cov teeb meem, vim tias nyob rau hauv tej yam khoom uas muaj cua sov yog tsim rau kev txav mus los ntawm cov khoom dawb. ntawm lub zog siv. Qhov no tuaj yeem muab piv rau yuav ua li cas nws yooj yim dua rau tus neeg los nyem los ntawm cov neeg coob coob uas txav mus los ntawm qhov chaw nyob ruaj khov. Cov kev daws teeb meem polymer muaj qhov taw qhia tseem ceeb ntawm kinematic viscosity, ntsuas hauv Stokes lossis Pascal vib nas this. Qhov no yog vim muaj nyob rau hauv lawv cov qauv ntawm ntev rigidly khi molecular chains. Tab sis raws li qhov kub thiab txias, lawv viscosity poob sai heev. Thaum cov khoom yas raug nias, nws cov filamentous, intricately intertwined molecules raug yuam mus rau hauv txoj hauj lwm tshiab.
Cov viscosity ntawm cov roj av ntawm qhov kub ntawm 20 ° C thiab atmospheric siab ntawm 101.3 Pa yog ntawm qhov kev txiav txim ntawm 10 -5 Pas. Piv txwv li, kinematic viscosity ntawm huab cua, helium, oxygen thiab hydrogen nyob rau hauv xws li tej yam kev mob yuav muab sib npaug rau 1.8210 -5, feem; 1, 9610-5; 2, 0210-5; 0.8810-5 Pas. Thiab cov kua helium feem ntau muaj cov cuab yeej zoo ntawm superfluidity. Qhov tshwm sim no, nrhiav tau los ntawm Academician P. L. Kapitsa, lus dag nyob rau hauv lub fact tias cov hlau nyob rau hauv xws li ib tug lub xeev ntawm aggregation yuav luag tsis muaj viscosity. Rau nws, daim duab no yuav luag xoom.
