The current repository contains raw data in the shape of images collected during a systematic laboratory study, examining the usability of the fractal dimension in the characterization of the flow regime. The study is presented in the paper by Karadimitriou et al., 2024. The two fluids were the wetting phase (WP), FluorinertTM, FC-43, and the non-wetting phase (NWP), deionized water mixed with ink, and occasionally with a specific amount of Glycerol. The wetting phase was initially introduced into the pore space of a Poly-Di-Methyl-Siloxane (PDMS) micromodel, fully saturating it. Then, primary drainage scenarios were realized with the introduction of the non-wetting phase under controlled-flux conditions. The objective of the study was to investigate the usability of the fractal dimension of various geometrical entities, like the interfaces between phases, and the bulk non-wetting phase occupancy of the pore space, in the characterization of the flow regime.

Main data The dataset is populated with the raw images acquired during a primary drainage process. Every drainage process took place under a fixed boundary volumetric flux, which is depicted in the title of each file, in terms of the corresponding capillary number. Additionally, the title of each file also includes the viscosity ratio between the invading and the defending phase. A typical file name is in the form Ca=,M=.tar. In the images, the non-wetting phase, namely water, shows as dark, and the wetting phase, namely Fluorinert, shows as transparent within the boundaries of the pore network. Flow takes place from right to left.

Procedure followed for each constant Ca and M experiment The term “experiment” pertains to the breakthrough of the non-wetting phase from its own inlet to the outlet, at a constant boundary flux. For every experiment, a fixed capillary number value, Cai, i = 1,2,3, is maintained, whereas the viscosity ratio between the invading and the defending phase remains the same through a single experiment. In order for the viscosity ratio to be fixed on demand, Glycerol was added to water at specific concentrations, so as to achieve the desired viscosity of water. The Ca used were 10-2, 10-3, 10-4, and 10-5. The viscosity ratios used were 0.2, 1, and 10. The flow network has overall dimensions of 15 by 20 millimeters, with a mean pore size of 410 microns, and a depth of 100 microns. It is an exact replication of the network used in the work of Sivanesapillai et al., 2018. The micromodel is initially saturated with the wetting phase. Then, the non-wetting phase is injected into the microfluidic pore network. The non-wetting phase is injected at a fixed volumetric flux to maintain a constant value of the capillary number, Ca, during the entire experiment. The wetting phase is getting passively displaced during this process. Even though the experiment, for the needs of the corresponding publication, concludes at breakthrough, some more images are acquired for future purposes.

CETONI QMixElements, v20190108

StreamPix, 9

ImageJ, 1.53

Karadimitriou N., Terzis, A., Metaftsis, V., Vahid Dastjerdi, S., Lee, D., & Steeb H. (2024), The effect of flow regime on the phase and inter-phase fractal dimension, To be submitted to WRR.