Li Linzhu, Iskander Magued
Civil and Urban Engineering Department, Tandon School of Engineering, New York University, 6 Metrotech Center, Brooklyn, NY 11201, USA.
J Imaging. 2022 Jan 30;8(2):32. doi: 10.3390/jimaging8020032.
Pore scale analysis of flow through porous media is of interest because it is essential for understanding internal erosion and piping, among other applications. Past studies have mainly focused on exploring macroscopic flow to infer microscopic phenomena. An innovative method is introduced in this study which permits visualization of interstitial fluid flow through the pores of a saturated synthetic transparent granular medium at the microscale. Several representative images of Ottawa sand were obtained using dynamic image analysis (DIA), for comparison with flow through perfect cylinders. Magnified transparent soil particles made of hydrogel were cast in 3D printed molds. Custom 3D printed jigs were employed for accurate positioning of the particles to ensure that particles have the same flow area within the soil. The pore fluid was embedded with silver-coated hollow microspheres that allowed for their florescence and tracking their movement within the model when illuminated by a laser light source. Images of the flow were captured from the model using a high-speed camera. This, along with particle image velocimetry (PIV) provided for the velocity and direction analysis of fluid flow movements within the pore space of a planar 2D model. Comparison of interstitial flow through homogeneous porosity-controlled Ottawa-shaped and cylindrical particles demonstrates that the magnitude of turbulence is related to particle roundness.
对多孔介质中的流动进行孔隙尺度分析很有意义，因为它对于理解内部侵蚀和管涌等应用至关重要。过去的研究主要集中在探索宏观流动以推断微观现象。本研究引入了一种创新方法，该方法允许在微观尺度上可视化饱和合成透明颗粒介质孔隙中的间隙流体流动。使用动态图像分析（DIA）获得了渥太华砂的几张代表性图像，以便与通过完美圆柱体的流动进行比较。由水凝胶制成的放大透明土壤颗粒被浇铸在3D打印模具中。使用定制的3D打印夹具对颗粒进行精确定位，以确保颗粒在土壤中的流动面积相同。孔隙流体中嵌入了镀银空心微球，当用激光光源照射时，这些微球能够发出荧光并跟踪它们在模型中的运动。使用高速相机从模型中捕获流动图像。这与粒子图像测速技术（PIV）一起，用于对平面二维模型孔隙空间内流体流动运动的速度和方向进行分析。通过均匀孔隙率控制的渥太华形状颗粒和圆柱形颗粒的间隙流动比较表明，湍流强度与颗粒圆度有关。
