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4D Synchrotron X-Ray Multi Projection Imaging (XMPI) for studying multiphase flow dynamics and flow instabilities in porous networks

Patrick Wegele, Zisheng Yao, Jonas Tejbo, Julia K. Rogalinski, Zhe Hu, Yuhe Zhang, Erfan Oliaei, Saeed Davoodi, Alexander Groetsch, Kim Nygård, Eleni Myrto Asimakopoulou, Tomas Rosén, Pablo Villanueva-Perez, L. Daniel Söderberg

Abstract

Flow instabilities such as Haines jumps in porous media are common phenomena that occur on sub-second timescales. X-rays are particularly suitable for investigating these processes because they provide non-destructive three-dimensional insight into the network structure and the liquid distribution within porous media. Studying imbibition events in four dimensions (three spatial dimensions plus time) is inherently challenging with conventional tomography because the required rapid sample rotation imposes significant centrifugal forces that alter the flow. Here, we demonstrate synchrotron X-ray multi-projection imaging (XMPI) to capture four-dimensional flow in an additively manufactured, homogeneous spherical pore network at 1.3 $μ$m effective pixel size and 50 Hz temporal resolution without the need for high rotational speeds. This enables in situ visualization of non-repeatable pore-scale events in both space and time, a capability unachievable with classical X-ray tomographic approaches. We compare the results to Shan-Chen multiphase Lattice Boltzmann simulations performed on the same geometry, finding both qualitative agreements and systematic differences in filling sequences and timescales. These discrepancies expose key limitations of current simulation methods in representing contact-line dynamics and realistic boundary conditions limitations that XMPI can directly overcome. By enabling high-resolution, real-time imaging of flow instabilities in opaque porous media, synchrotron XMPI provides a unique platform that bridges the gap between pore-scale experiments and simulations.

4D Synchrotron X-Ray Multi Projection Imaging (XMPI) for studying multiphase flow dynamics and flow instabilities in porous networks

Abstract

Flow instabilities such as Haines jumps in porous media are common phenomena that occur on sub-second timescales. X-rays are particularly suitable for investigating these processes because they provide non-destructive three-dimensional insight into the network structure and the liquid distribution within porous media. Studying imbibition events in four dimensions (three spatial dimensions plus time) is inherently challenging with conventional tomography because the required rapid sample rotation imposes significant centrifugal forces that alter the flow. Here, we demonstrate synchrotron X-ray multi-projection imaging (XMPI) to capture four-dimensional flow in an additively manufactured, homogeneous spherical pore network at 1.3 m effective pixel size and 50 Hz temporal resolution without the need for high rotational speeds. This enables in situ visualization of non-repeatable pore-scale events in both space and time, a capability unachievable with classical X-ray tomographic approaches. We compare the results to Shan-Chen multiphase Lattice Boltzmann simulations performed on the same geometry, finding both qualitative agreements and systematic differences in filling sequences and timescales. These discrepancies expose key limitations of current simulation methods in representing contact-line dynamics and realistic boundary conditions limitations that XMPI can directly overcome. By enabling high-resolution, real-time imaging of flow instabilities in opaque porous media, synchrotron XMPI provides a unique platform that bridges the gap between pore-scale experiments and simulations.
Paper Structure (14 sections, 22 equations, 14 figures, 1 table)

This paper contains 14 sections, 22 equations, 14 figures, 1 table.

Table of Contents

  1. Introduction
  2. Materials
  3. Methods
  4. Viscous and capillary pressure drop during pore filling
  5. XMPI experimental setup
  6. Data processing and 4D reconstruction
  7. Multiphase Lattice Boltzmann Simulation
  8. Results and Discussion
  9. Simulation Results
  10. Experimental results
  11. Comparison
  12. Conclusion
  13. XMPI data preprocessing
  14. 4D reconstruction using X-Hexplane

Figures (14)

  • Figure 1: Cut through the 3D model of the capillary that was used during the experiment. The hollow-spherical structure is visible in the middle, while a circular section above and below is used to provide in- and outflow areas
  • Figure 2: Schematic pore filling mechanism of a network of intersecting hollow spheres.
  • Figure 3: XMPI experimental setup. Crystals 1-3 are used to split the central beam into two beamlets that intersect within the investigated object. Afterwards, the beamlets are captured by X-ray detector systems Cam 1 and Cam 2.
  • Figure 4: Tomographic rotation stage with PMMA cylinder and a mounted sample. The beamlets intersect within the sample after transmitting the PMMA holder while a connection to Kapton tubing allows for generating a flow through the sample.
  • Figure 5: Process of creating a binarized simulation geometry out of the synchrotron tomograph. Process is shown for stack image 34 in the yz-plane.
  • ...and 9 more figures