منابع مشابه
Viscosity Solutions for a Polymer Crystal Growth Model
We prove existence of a solution for a polymer crystal growth model describing the movement of a front (Γ(t)) evolving with a nonlocal velocity. In this model the nonlocal velocity is linked to the solution of a heat equation with source δΓ. The proof relies on new regularity results for the eikonal equation, in which the velocity is positive but merely measurable in time and with Hölder bounds...
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Lu = aij(x)Diju for u ∈ C(Ω). Suppose u ∈ C(Ω) is a supersolution in Ω, i.e. Lu ≤ 0. Then if φ ∈ C(Ω) satisfies Lφ > 0, we get L(u− φ) < 0 in Ω, hence by the maximum principle, u− φ does not have interior local minima in Ω. Put differently, if φ ∈ C(Ω) is such that u− φ has a local minimum at x0 ∈ Ω, then necessarily Lφ(x0) ≤ 0. Geometrically, u− φ having a local minimum at x0 means that the gr...
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We use a modified filament stretching rheometer to quantify the influence of a known controlled pre-shear history on the transient extensional viscosity of a dilute polymer solution. Two different types of pre-deformation are explored; both influence the subsequent stretching significantly, albeit in opposite ways. Small-amplitude oscillatory straining parallel to the direction of stretching en...
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Polymer flooding is now considered a technicallyand commercially-proven method for enhanced oil recovery (EOR). The viscosity of the injected polymer solution is the key property for successful polymer flooding. Given that the viscosity of a polymer solution has a non-linear relationship with various influential parameters (molecular weight, degree of hydrolysis, polymer concentration, cation c...
متن کاملViscosity enhancement In non-Newtonian flow of dilute polymer solutions through crystallographic porous media
In many practical flow situations solutions of flexible polymers are found to exhibit a well-known non-Newtonian viscosity enhancement effect. This is likely to be due to extensional components in the flow field, which can cause flexible polymer molecules to stretch and orientate, causing an increase in the extensional viscosity. This viscosity enhancement is important in many industrial applic...
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ژورنال
عنوان ژورنال: Journal of Chemical Education
سال: 1992
ISSN: 0021-9584,1938-1328
DOI: 10.1021/ed069p818.1