(The) converging of a viscoelastic fluid점탄성유체의 수축 흐름

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For a viscoelastic fluid, the characteristics of normal stress and normal stress difference in a converging channel was analyzed. In a constrained converging flow, the stress equation was obtained by perturbation method and Coleman-Noll and connected Maxwell models were used as a constitutive equation. An extensional stress, $-\tau$ rr, shows a same increasing -decreasing phenomena along the centerline in above two models. But in the profiles of normal stares difference, -($\tau$ rr-$\tau\,\theta\,\theta$), two models show difference. -($\tau$ rr-$\tau\,\theta\,\theta$) has a maximum peak in Coleman-Noll model but this value increases monotonously in Maxwell model. In a free converging flow, computer simulation was used with ColemanNoll model. A normal stress difference, $\tau$ xx-$\tau$ yy, represents increasingdecreasing phenomena along the centerline in this geometry as same as in the constrained converging geometry. But an extra stress, Sxx, is increasingdecreasing, thereafter, decreasing-increasing whereas the extra stress is increasing monotonously in case of constrained converging flow. The temperature distribution in a free converging channel was obtained considering heat dissipation. Coleman-Noll model, which have a temperaturedependent constant, was used. At the vicinity of abrupt contraction, temperature-rise is high and has a maximum value. Temperature -rise is strongly affected by Brinkman number and Pechlet number. At high heat dissipation, the normal stress difference is affected by heat dissipation and the value of this is decreased. With an introduction of molecular dynamics, the constitutive equation was developed. We extended Doi``s theory by proposing a new process of equilibrium across slip-links of polymer. The stress equation developed allows a smooth transition from Doi``s process A to B at the initial stage of stress relaxation in the simple shear deformation. The relaxation spectrum of normal stress difference was obtained for differen...
Advisors
Chung, In-Jae정인재
Description
한국과학기술원 : 화학공학과,
Publisher
한국과학기술원
Issue Date
1990
Identifier
61487/325007 / 000775527
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학공학과, 1990.2, [ [v], 127 p. ]

URI
http://hdl.handle.net/10203/29222
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=61487&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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