胶粘剂分散液中的不连续剪切稀化,Physical Review Fluids

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胶粘剂分散液中的不连续剪切稀化
Physical Review Fluids ( IF 2.5 ) Pub Date : 2019-07-18 , DOI: 10.1103/physrevfluids.4.074307
Ehsan Irani , Pinaki Chaudhuri , Claus Heussinger

我们提供了在密实状态下模型胶粘剂分散体的稳态剪切流变学的模拟。我们改变了有吸引力的粒子间作用力的范围

ü

以及耗散的力量

b

。对于较大的耗散力，流变受魏森伯格数控制

无线网 〜 b \dot{γ} / ü

并显示Herschel-Bulkley表格

σ = σ_{ÿ} + C {无线网}^{ν}

有指数

ν = 0.45

。降低耗散强度，Wi的缩放比例会分解，并且会出现惯性效应。压力通过Johnson-Samwer定律降低

Δ σ 〜 Ť_{s}^{2个 / 3}

，温度

Ť_{s}

完全是由于剪切引起的振动。在流动过程中，粒子彼此滑行，从而它们的相对速度主要切向指向粒子表面。能量消耗的切向通道及其抑制导致流量曲线的不连续性以及相关的不连续的剪切稀化过渡。我们建立了一个与摩擦系统的类比，其中发生了不连续的剪切增稠现象。在这两种情况下，切向力（摩擦力或粘滞力）会介导从流量曲线的一个分支（切向损耗低）到切向损耗大的过渡。

"点击查看英文标题和摘要"

Discontinuous shear-thinning in adhesive dispersions

We present simulations for the steady-shear rheology of a model adhesive dispersion in the dense regime. We vary the range of the attractive interparticle forces

u

as well as the strength of the dissipation

b

. For large dissipative forces, the rheology is governed by the Weissenberg number

Wi \sim b \dot{γ} / u

and displays Herschel-Bulkley form

σ = σ_{y} + c {Wi}^{ν}

with exponent

ν = 0.45

. Decreasing the strength of dissipation, the scaling with Wi breaks down and inertial effects show up. The stress decreases via the Johnson-Samwer law

Δ σ \sim T_{s}^{2 / 3}

, where temperature

T_{s}

is exclusively due to shear-induced vibrations. During flow, particles slide past each other such that their relative velocities are primarily directed tangentially to the particle surfaces. This tangential channel of energy dissipation and its suppression leads to a discontinuity in the flow curve and an associated discontinuous shear-thinning transition. We set up an analogy with frictional systems, where the phenomenon of discontinuous shear-thickening occurs. In both cases, tangential forces, frictional or viscous, mediate a transition from one branch of the flow curve with low tangential dissipation to one with larger tangential dissipation.

更新日期：2019-07-18

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