Research Progress on Micro/Nanopore Flow Behavior

Abstract

Fluid flow in microporous and nanoporous media exhibits unique behaviors that deviate from classical continuum predictions due to dominant surface forces at small scales. Understanding these microscale flow mechanisms is critical for optimizing unconventional reservoir recovery and other energy applications. This review provides a comparative analysis of the existing literature, highlighting key advances in experimental techniques, theoretical models, and numerical simulations. We discuss how innovative micro/nanofluidic devices and high-resolution imaging methods now enable direct observation of confined flow phenomena, such as slip flow, phase transitions, and non-Darcy behavior. Recent theoretical models have clarified scale-dependent flow regimes by distinguishing microscale effects from macroscopic Darcy flow. Likewise, advanced numerical simulations-including molecular dynamics (MD), lattice Boltzmann methods (LBM), and hybrid multiscale frameworks-capture complex fluid-solid interactions and multiphase dynamics under realistic pressure and wettability conditions. Moreover, the integration of artificial intelligence (e.g., data-driven modeling and physics-informed neural networks) is accelerating data interpretation and multiscale modeling, offering improved predictive capabilities. Through this critical review, key phenomena, such as adsorption layers, fluid-solid interactions, and pore surface heterogeneity, are examined across studies, and persistent challenges are identified. Despite notable progress, challenges remain in replicating true reservoir conditions, bridging microscale and continuum models, and fully characterizing multiphase interface dynamics. By consolidating recent progress and perspectives, this review not only summarizes the state-of-the-art but underscores remaining knowledge gaps and future directions in micro/nanopore flow research.

Keywords: artificial intelligence; confined flow behavior; experimental research; lattice Boltzmann method; microseepage; molecular dynamics simulation; nanoporous media; pore-scale modeling.

Figure 1

Schematic illustration of typical cross-domain applications enabled by micro/nanopore fluid dynamics.

Figure 2

World map showing the number of publications in micro/nanofluidic chip research by country (2015–2024). China is highlighted in red, reflecting its status as the second-largest contributor globally (after the United States) based on a meta-analysis of publication records.

Figure 3

Velocity distribution under different radii and slip lengths (P = 106 Pa, T = 296.15 K): (a,c,e) with no slip conditions; (b,d,f) with slip conditions [65].

Figure 4

Different types of flow models: (a) no slip; (b) negative slip; (c) positive slip.

Figure 5

Development of traditional core experiments to modern microfluidic technology. (a) Three-dimensional tomography images of real cracks are used to create micromodels [81]. (b) Irregular 2D silicon micromodels with dry etching of porous structures are achieved through microfabrication techniques, and 2D PDMS micromodels with regular patterns are established through soft lithography techniques [87,88]. The channel width ranges between 10 and 20 μm. (c) Image sequences of capillary flow in open rectangular channels with a width of 200 μm and a depth of 177 μm [89]; (d) Single pore channels and porous media channels established by simulating blind end fractures in shale reservoirs [90]. (e) The length of the single tube is 2 mm, the width is 3 μm, and the depths are 1000 and 30 nm, respectively. The mixed phase pressure is measured [91].

Figure 6

Micro/nano fluidic physical simulation system.

Figure 7

Comparison of visualization systems for three optical imaging technologies, each column including principle diagram, typical output image, and energy application example: (1) laser confocal microscope [95,96]; (2) scanning electron microscope [97,98]; (3) X-ray microscopy CT [99,100].