多孔介质中快速三维X射线粒子追踪测速的直接轨迹重建
Direct Trajectory Reconstruction for Fast 3D X-ray Particle Tracking Velocimetry in Porous Media
- Ghent University（根特大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
针对多孔介质中快速流动的3D-3C测速，提出直接轨迹重建算法CTracks，绕过CT重建，实现最大可检测速度提升五倍。
AI中文摘要：
X射线层析粒子追踪测速是一种很有前景的工具，可提供不透明多孔介质内部流体流动的孔隙尺度洞察。这对于从地热能到电化学等应用至关重要。当前实现这种三维三分量（3D-3C）测速技术的方法使用传统的微计算机断层扫描（CT）工作流程来恢复示踪粒子轨迹。这些工作流程首先从跨越多个视角角度、按时间间隔顺序采集的射线照片中重建一系列三维CT图像。然后在这些CT图像中检测示踪粒子，最后将其连接成轨迹。然而，静态CT体积重建引起的运动模糊损害了快速移动示踪粒子的可检测性，严重限制了测速结果的时间分辨率和动态范围。在这项工作中，我们表明可以通过直接从采集的射线照片中显式恢复粒子轨迹来克服这一限制，绕过中间断层重建步骤以及传统三维CT重建的静态场景假设。我们在一个新的开源算法CTracks中实现了这种方法，并使用管流和通过复杂多孔介质流动的实验数据对其进行了验证，证明与最先进的方法相比，最大可检测速度提高了五倍。数值模拟进一步证实了在这些增加的速度下检测率得到提高且轨迹误差有界。因此，我们的工作表明，通过用直接粒子轨迹重建替代X射线断层图像重建，不透明微观几何中的3D-3C测速可以扩展到显著更快的流动。
英文摘要：
X-ray tomographic particle tracking velocimetry is a promising tool to provide pore-scale insight into fluid flow inside opaque porous media. This is critical for applications ranging from geo-energy to electrochemistry. Current approaches to implement this three-dimensional, three-component (3D-3C) velocimetry technique use conventional micro-computed tomography (CT) workflows to recover tracer particle trajectories. These workflows first reconstruct a sequence of 3D CT images from radiographs which are sequentially acquired at time intervals that span multiple viewing angles. The tracer particles are then detected in each of these CT images and finally linked into trajectories. However, motion-blurring induced by the static CT volume reconstruction impairs the detectability of fast-moving tracer particles, severely limiting the temporal resolution and dynamic range of the velocimetry outcome. In this work, we show that this limitation can be overcome by explicitly recovering particle trajectories directly from the acquired radiographs, bypassing the intermediate tomographic reconstruction step and the static-scene assumptions of traditional 3D CT reconstructions. We implement this approach in a new open-source algorithm, CTracks, and validate it using experimental data on pipe flow and on flow through a complex porous medium, demonstrating a five-fold increase in the maximum detectable velocity compared with state-of-the-art methods. Numerical simulations further confirm improved detection rates and bounded trajectory errors at these increased velocities. Our work thus demonstrates that 3D-3C velocimetry in opaque microscopic geometries can be extended to substantially faster flows by replacing X-ray tomographic image reconstruction with direct particle trajectory reconstruction.
