AI 中文总结
本研究采用光学相干断层扫描（OCT），首次在一次沉降实验中连续同步获取浓土豆淀粉悬浮液的沉降速度与颗粒浓度，验证了其可作为探测浓悬浮液内部动力学的可行工具。
AI 中文摘要
本文展示光学相干断层扫描（OCT）可作为浓、光学不透明悬浮液的测量技术，传统光学方法无法探测这类悬浮液的内部结构，而OCT能将单个土豆淀粉颗粒（约20μm）分辨为独立散射体，即便该悬浮液肉眼看似不透明。通过追踪同一OCT图像序列中载粒层的垂直重心位置⟨Z⟩(t)和上清液边界Z_sup(t)，我们可同时且连续地获取瞬时沉降速度V(t)和随时间演化的有效体积分数φ_eff(t)。据我们所知，这是首次在一次沉降实验中同时测量沉降速度和颗粒浓度的单一连续轨迹，传统批量测量每次实验仅能得到一个速度值。我们将该方法应用于浓土豆淀粉悬浮液，采用多钨酸钠水溶液，使初始体积分数φ_0在0.30至0.50之间变化，溶剂密度ρ_L在1.0至1.3×10³kg·m⁻³之间变化。归一化速度V/V_Stokes对φ_eff作图，在φ_eff≈0.30至0.52范围内呈现出与Krieger-Dougherty模型和Richardson-Zaki定律均一致的共同趋势，证实该方法能捕捉到物理上合理的受阻沉降行为。这些结果确立了OCT作为探测此前光学测量无法触及的浓悬浮液内部动力学的可行工具。
英文摘要
We demonstrate optical coherence tomography (OCT) as a measurement technique for dense, optically opaque suspensions. Conventional optical methods cannot access the interior of such suspensions. OCT resolves individual potato-starch particles (${\sim}20~\mathrm{μm}$) as distinct scatterers, even though the suspension appears opaque to the eye. By tracking the vertical centroid position of the particle-laden layer $\langle Z \rangle(t)$ and the supernatant boundary $Z_\mathrm{sup}(t)$ in the same OCT image sequence, we obtain the instantaneous settling velocity $V(t)$ and the time-evolving effective volume fraction $ϕ_\mathrm{eff}(t)$ simultaneously and continuously in time. To our knowledge, this is the first measurement to combine settling velocity and particle concentration into a single continuous trajectory within one sedimentation run. Conventional batch measurements yield only one velocity value per run. We applied this method to dense potato-starch suspensions, varying the initial volume fraction $ϕ_0$ from 0.30 to 0.50 and the solvent density $ρ_\mathrm{L}$ from 1.0 to $1.3{\times}10^3~\mathrm{kg~m^{-3}}$ using aqueous sodium polytungstate solutions. The normalized velocity $V/V_\mathrm{Stokes}$ plotted against $ϕ_\mathrm{eff}$ collapses onto a common trend consistent with both the Krieger--Dougherty model and the Richardson--Zaki law over $ϕ_\mathrm{eff} \simeq 0.30$--$0.52$, confirming that the method captures physically reasonable hindered-settling behavior. These results establish OCT as a viable tool for probing internal dynamics in dense suspensions that were previously inaccessible to optical measurement.
Comments8 pages, 5 figures
