Breakup of shear-thickening suspension

The influence of rheological properties on the breakup process of shear-thickening suspensions is studied in this paper. Using high-speed photography, we analyze the breakup morphology of cornstarch-water suspensions with different rheological behaviors. The processes of droplet formation and breakup of the cornstarch-water suspensions is divided into three stages: thinning stage, thickening stage, and diluted stage. In the thickening stage, shear-thickening behavior apparently slows the deformation of the droplet throat, and the throat diameter $D_m$ follows a power law with breakup time, $D_m\propto {\left(t_p-t\right)}^{1/5}$. A unique solidlike phenomenon occurs when the volume fraction of the suspension is $\phi >43\%$ and a slip plane forms, which resembles a cylindrical metal rod stretched by uniaxial tensile loading.

Figure 1

The cumulative size distribution of the cornstarch.

Figure 2

(a) Schematic of the experimental equipment. (b) Sketch of the throat diameter.

Figure 3

Rheological property measurements: (a) apparent viscosity η vs shear rate $\dot{\gamma }$; (b) apparent viscosity η vs shear stress τ, where the solid line with $\mathrm{slope}=1$ represents a constant shear rate that is related to DST behavior.

Figure 4

The breakup and throat morphology near the breakup of a droplet of suspension at volume fractions of (a) $\phi =35\%$ and (b) $\phi =41\%$, where $t_p$ is the time of breakup.

Figure 5

Development of the throat diameter $D_m$ for $\phi =35\%\text{–}43\%$, where $t_p$ is the time of breakup.

Figure 6

The breakup and throat morphology near the breakup of a droplet of suspension at volume fractions of (a) $\phi =45\%$ and (b) $\phi =49\%$.

Figure 7

The development of the throat diameter $D_m$ for $\phi =45\%\text{–}51\%$, where $t_p$ is the time of breakup.

Figure 8

The angle of the slip plane of the suspension at various volume fractions prior to breakup.

Figure 9

The angle of the slip plane at various volume fractions of the suspension.

Figure 10

The phase diagram of suspension breakup for different rheological properties.

Figure 11

Development of surface roughness during the breakup process.

Figure 12

(a) The throat morphology near the breakup of a cornstarch-water suspension droplet. (b) Slip lines in the area of plastic deformation in a metal rod consisting of single crystals. (c) Force analysis of a cylindrical metal rod under a uniaxial tensile force.