Figure 2: Spatial and temporal variation of the flow velocity. | Nature Communications

Figure 2: Spatial and temporal variation of the flow velocity.

From: Fabrication of slender elastic shells by the coating of curved surfaces

Figure 2

(a) Schematic diagram of the coating problem; h(φ, t) is the thickness of the viscous film and u(φ, t) is the flow velocity during drainage. (bd) All data is for VPS-32 at 20 °C. (b) Instantaneous velocity field at t=60 s in a 1 × 1 cm2 region of the film located at φ=60° of a sphere (R=38 mm), obtained through PIV. (c) Dependence of the instantaneous local velocity (at t=60 s) on φ. (d) Time variation of the velocity, u(φ=60°, t) orange circles, and the viscosity, μ(t) blue triangles, of the polymer. The characteristic curing time, τc, separates the drainage and curing regimes for both u(φ, t) and μ(t). The dash-dot line is the best fit for the viscosity: equation (5) with μ0=7.1±0.2 Pa s, α=5.3±0.7, β=(2.06±0.09) × 10−3, and  s. The solid and dashed lines are the predictions from our model for the velocity field using equation (4) and direct numerical simulations, respectively.

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