Liquid Transport Research Articles

Solution landscape of droplets on rough surfaces: wetting transition and directional transport.

Droplets on rough surfaces can exhibit various stationary states that are crucial for designing hydrophobic materials and enabling directional liquid transport. Here, we introduce a phase-field saddle dynamics method to construct the solution landscape of wetting transition and directional transport on pillared substrates. By applying this method, we reveal the full range of Cassie-Baxter and Wenzel states, along with the complete wetting transition paths. We further elucidate the mechanisms of directional droplet transport on both hydrophobic and hydrophilic surfaces, demonstrating how surface design can influence directional movement.

Preparation of Long-Range Ordered 1D Nanowire Arrays on PVP-Modified Hydrophobic Highly Adhesive Templates Using Conical Fiber Arrays.

Suspended nanoscale one-dimensional (1D) arrays have attracted substantial interest due to their promising applications in nanodevice fabrication. In this study, we propose a novel strategy for fabricating precisely positioned, long-range ordered nanowire arrays by controlling the directional liquid transport of conical fiber arrays (CFAs) on asymmetrically modified silicon templates patterned with periodic spindle-shaped micropillars. The intrinsic properties of CFAs and the tailored wettability of silicon templates play critical roles in nanowire fabrication. CFAs generates quasi-unidirectional surface tension (Fγ), facilitating precise control over the retraction of liquid films and ensuring strict nanowire alignment in the dewetting direction. Meanwhile, high-adhesion hydrophobic surfaces effectively enhance the pinning behavior of the three-phase contact line during the retraction process, thereby improving the liquid bridge stability. It is noteworthy that the method developed for preparing high-yield arrays of ultralong nanowires exhibits remarkable universality. This approach can be widely applied to the synthesis of suspended nanowires using diverse polymers such as polystyrene sulfonic acid, poly(vinyl alcohol), polyvinylpyrrolidone, polyethylene glycol, and sodium alginate as solutes, achieving a robust formation rate exceeding 80% for nanowires that surpass 16 μm in length. These findings contribute valuable knowledge for the scalable production of suspended 1D nanostructures, furthering advancements in nanoscale device development.

Compositional-Asymmetry-Induced Transition of Directional Liquid Transport on Tilted and Janusian Nanohair Arrays.

Anisotropic wetting on certain surfaces endowed with structural asymmetry or compositional gradients commonly impedes the directional adjustment of liquid transport. We report here that directional liquid transport (DLT) against the tilt direction of nanohair and in the reverse direction was achieved on tilted-nanohair arrays (TNAs) and tilted-Janusian-nanohair arrays (TJNAs), respectively. Janusian compositional asymmetry on the surface of TJNAs was created by plasma polymer deposition on structurally asymmetric TNAs previously fabricated by Faraday-cage-assisted plasma nanotexturing. The structurally asymmetric TNAs led to DLT against the tilting direction due to the asymmetric wetting under the capillary imbibition between tilted nanohairs and the preferential coalescence of liquid against the tilt direction. The Janusian compositional asymmetry of TJNAs changing the capillarity imbibition condition between tilted nanohairs resulted in the transition of the liquid spreading direction along the tilt direction. The spreading direction along and against the tilt direction is predicted through a comprehensive analysis of the structural and compositional asymmetries of the TNAs and TJNAs.

Nanocapillary Core-Annular Flows of Immiscible Active and Non-Active Liquids Trigger External-Drive-Free Nanofluidic Liquid Transport.

In this paper, we develop analytical solutions for investigating the nanocapillary core-annular transport of an active liquid and an immiscible non-active liquid. The active liquid contains active particles that show vortex defects, which trigger a circular polarization field, eventually enabling the generation of an induced pressure-driven flow inside the active fluids in the presence of an axial gradient in the activity (or the concentration of the active particles). Here we consider two separate scenarios. For the first (second) case, the active liquid occupies the core (annular) region while the non-active liquid occupies the annular (core) region. Our main finding is that for both of these cases, the active flow drives the non-active flow and can achieve a significant volume flow rate (of the non-active flow) in the presence of an appropriate strength of activity (or concentration of the active particles); therefore, such significant nanofluidic transport of the driven fluid occurs with no external driving (such as an external pressure gradient or an applied axial electric field). Also, for both of these cases, a greater thickness of the active liquid layer increases the flow strength across the entire nanocapillary but causes a nonmonotonic variation of the volume flow rate of the non-active liquid. Furthermore, for the case where the active liquid occupies the core, a larger active:non-active liquid viscosity ratio significantly enhances the overall transport; however, for the other case, the viscosity ratio has no effect. Finally, we provide our analytical results for the case where there is a finite slip at the nanocapillary walls. We find that depending on the scenario (active liquid occupying the core or the annular region), different signs of the slip lengths have different influences on the overall magnitude and direction of the velocity field in the system and the flow rate in the driven liquid.

A Column-Generation-Based Exact Algorithm to Solve the Full-Truckload Vehicle-Routing Problem

This study addresses a specialized variant of the full-truckload delivery problem inspired by a Turkish logistics firm that operates in the liquid transportation sector. An exact algorithm is proposed for the relevant problem, to which no exact approach has been applied before. Multiple customer and trailer types, as well as washing operations, are introduced simultaneously during the exact solution process, bringing new aspects to the exact algorithm approach among full-truckload systems in the literature. The objective is to minimize transportation costs while addressing constraints related to multiple time windows, trailer types, customer types, product types, a heterogeneous fleet with limited capacity, multiple departure points, and various actions such as loading, unloading, and washing. Additionally, the elimination or reduction of waiting times is provided along transportation routes. In order to achieve optimal solutions, an exact algorithm based on the column generation method is proposed. A route-based insertion algorithm is also employed for initial routes/columns. Regarding the acquisition of integral solutions in the exact algorithm, both dynamic and static sets of valid inequalities are incorporated. A label-setting algorithm is used to generate columns within the exact algorithm by being accelerated through bi-directional search, ng-route relaxation, subproblem selection, and heuristic column generation. Due to the problem-dependent structure of the column generation method and acceleration techniques, a tailored version of them is included in the solution process. Performance analysis, which was conducted using artificial input sets based on the real-life operations of the logistics firm, demonstrates that optimality gaps of less than 1% can be attained within reasonable times even for large-scale instances relevant to the industry, such as 120 customers, 8 product and 8 trailer types, 4 daily time windows, and 40 departure points.

Janus Textile: Advancing Wearable Technology for Autonomous Sweat Management and Beyond.

To alleviate the discomfort caused by excessive sweating, there is a growing emphasis on developing wearable textiles that can evacuate sweat autonomously. These advanced fabrics, unlike their absorbent and retention-prone predecessors, harness the Janus structure-distinguished by its asymmetric wettability-to facilitate one-way transport of liquid. This unique characteristic has significant potential in addressing issues related to excessive bodily moisture and propelling the realm of smart wearables. This review offers a comprehensive overview of the advancements in Janus-structured textiles within the wearable field, delving into the mechanisms behind their unidirectional liquid transport, which rely on chemical gradient and curvature gradient strategies, alongside the methodologies for achieving asymmetric wettability. It further spotlights the multifaceted applications of Janus-based textiles in wearables, including moisture and thermal management, wound care, and sweat analysis. In addition to examining existing hurdles, the review also explores avenues for future innovation, envisioning a new era of Janus textiles tailored for personalized comfort and health monitoring capabilities.

Impact of detailed liquid water transport in channel on mass transfer and performance of proton exchange membrane fuel cell

Impact of detailed liquid water transport in channel on mass transfer and performance of proton exchange membrane fuel cell

Fluctuation and aggregation dynamics of solid–liquid flow in deep-sea mining pipelines under lateral vibration

Research on the fluctuation characteristics and the transition mechanisms of particle group motion in vibrating deep-sea mining pipelines is insufficient currently. To clarify the mechanisms behind the effects of vibration parameters and transport concentration on local particle aggregation and velocity fluctuations, this study investigates the fluctuation and unsteady characteristics of solid–liquid two-phase transport in large-scale vertical deep-sea mining rigid pipelines under lateral vibration conditions. Using a coupled Euler–Lagrange framework for simulation, the study mainly focuses on individual variables, quantitatively assessing the impact of particle concentration, pipeline amplitude, and frequency on particle velocity and local volume concentration fluctuations, elucidating the formation and transition mechanisms of particle motion patterns under different operating conditions. The results show that low-frequency vibrations promote spiral flow along the pipeline wall, enhancing the uniformity of particle distribution. Special-frequency vibrations of 0.75 Hz exacerbate local particle aggregation, increasing the concentration fluctuation rate by an additional 5% by resonance effects. An amplitude threshold exceeding 1.5 A* nonlinearly increased the unsteady characteristics within the pipeline, resulting in a notable increase in approximately 10% in the maximum particle volume concentration fluctuation. When particle concentration exceeds 50% of the rated concentration, the axial particle velocity fluctuation rate nearly doubles. These findings suggest that controlling vibration parameters and optimizing particle concentration are key to managing fluctuation characteristics, avoiding specific pipeline frequencies and ensuring the vibration amplitude below a certain threshold can help reduce aggregation and blockage risks. This is crucial for ensuring stable and efficient particle transport during deep-sea mining operations.

Cross-scale modeling and 6E analysis of a cold storage Rankine-Carnot battery and PEMFC coupled system for liquid hydrogen maritime transportation

Cross-scale modeling and 6E analysis of a cold storage Rankine-Carnot battery and PEMFC coupled system for liquid hydrogen maritime transportation

The mass transport characteristics and performance improvement with the nonuniform block flow channel in a proton exchange membrane fuel cell

The gas flow field significantly impacts the output power of proton exchange membrane fuel cells (PEMFCs). A nonuniform design is developed in this study to optimize the arrangement of blocks in the flow field, thereby enhancing PEMFC output power. Numerical simulations indicate nonuniform block arrangements significantly enhancing mass transfer performance compared to uniform arrangements. Under 0.4 V working voltage, the new design has increased power density by 4.84%. The flow field with three blocks positioned near the outlet effectively leverages the entrance effect and disrupts the thicker boundary layer. This improvement in mass transfer increases the reactant concentration in the catalyst layer, enhancing the reaction process. The efficiency of liquid water transport has also been enhanced by blocks near the flow field outlet, helping to mitigate water flooding. The impact of varying block arrangements and quantities on gas flow resistance is assessed through pumping power of cathode. Results indicate that for the same number of blocks, the pumping power remains identical in both uniform and nonuniform flow fields. With the same rear block arrangement, increasing the number of blocks significantly raises pumping power. As the block count increases from 3 to 7, the pumping power increases by as much as 64.7%. However, the change in current density is not significant. Therefore, adopting a nonuniform block arrangement in the flow field is a simple yet effective strategy to enhance PEMFC performance.

PAN/Zein/BiOCl fibrous membranes with ultrafast liquid transport channels and petal-textured energy conversion layers for oil–water separation and photocatalytic degradation

PAN/Zein/BiOCl fibrous membranes with ultrafast liquid transport channels and petal-textured energy conversion layers for oil–water separation and photocatalytic degradation

A Janus Fabric with Hexagonal Microcavity Channels for Efficient Urine Transport and Accurate Physiological Monitoring.

The current research on wearable electrochemical sensors for urine monitoring is relatively rare, which is primarily limited by the lack of an active management mechanism to effectively manipulate the transportation of excessive liquids. In this work, a Janus fabric with hexagonal microcavity channels (HMJ-FT) was assembled based on a disposable facial towel, which was further introduced to develop the wearable electrochemical sensor (HMJ-Sensor) for the directional manipulation of urine transportation and simultaneous detection of dopamine (DA) and uric acid (UA). The designed hexagonal microcavity structure can synergistically promote horizontal migration and vertical transport of liquid, thus ensuring efficient and rapid manipulation of urine transportation and preventing its accumulation and reflux, which are essential for accurate, real-time monitoring. Therefore, the constructed HMJ-Sensor demonstrated a lower limit of detection (LOD) compared to most reported wearable sensors, which is 10.0770 nM for DA and 1.4100 nM for UA, respectively. Additionally, it also has the widest detection range known to date (DA: 0.0360-4000 μM; UA: 0.0050-6000 μM), which can better adapt to the large volume of urine transport and significant fluctuations on urine concentration in practical applications. After being subjected to a 120-day storage period along with multiple bending, rubbing, and washing treatments, the HMJ-Sensor maintained its excellent detection performance, indicating its high stability and reliability. This work not only provided a novel strategy for the manipulation of urine transport but also enhanced the detection capabilities of urine monitoring, which holds significant potential for boosting wearable applications and medical monitoring in physiological and clinical settings.

Theory and Modeling of Transport for Simple Fluids in Nanoporous Materials: From Microscopic to Coarse-Grained Descriptions.

We present the state-of-the-art of theoretical modeling, molecular simulation, and coarse-graining strategies for the transport of gases and liquids in nanoporous materials (pore size 1-100 nm). Special emphasis is placed on the transport of small molecules in zeolites, active carbons, metal-organic frameworks, but also in nanoporous materials with larger pores such as ordered and disordered mesoporous oxides. We present different atomistic and mesoscopic methods as well as available theoretical formalisms to describe such a complex problem. Attention is given to the investigation of different molecular transport coefficients─including the self, collective and transport diffusivities─but also to the determination of free energy barriers and their role in overall adsorption/separation process rates. We further introduce other available approaches such as hierarchical simulations and upscaling strategies. This review focuses on simple fluids in prototypical nanoporous materials. While the phenomena covered here capture the main physical mechanisms in such systems, complex molecules will exhibit additional specific features. For the sake of clarity and brevity, we also omit multicomponent systems (e.g., fluid mixtures, electrolytes, etc.) and electrokinetic effects arising when charged systems are considered (ionic species, charged surfaces, etc.), both of which add to the complexity.

Rumen-Targeted Mining of Enzymes for Bioenergy Production.

Second-generation biofuel production, which aims to convert lignocellulose to liquid transportation fuels, could be transformative in worldwide energy portfolios. A bottleneck impeding its large-scale deployment is conversion of the target polysaccharides in lignocellulose to their unit sugars for microbial fermentation to the desired fuels. Cellulose and hemicellulose, the two major polysaccharides in lignocellulose, are complex in nature, and their interactions with pectin and lignin further increase their recalcitrance to depolymerization. This review focuses on the intricate linkages present in the feedstocks of interest and examines the potential of the enzymes evolved by microbes, in the microbe/ruminant symbiotic relationship, to depolymerize the target polysaccharides. We further provide insights to how a rational and more efficient assembly of rumen microbial enzymes can be reconstituted for lignocellulose degradation. We conclude by expounding on how gains in this area can impact the sustainability of both animal agriculture and the energy sector.

Liquid Transportation Distance Prediction Method for LNG Long-distance Pipeline Based on LSTM Algorithm

Liquid Transportation Distance Prediction Method for LNG Long-distance Pipeline Based on LSTM Algorithm

Construction of 3D-fabric-based triple-decker agar/sodium alginate/Ca2+ dual-network composite for wound dressing.

Construction of 3D-fabric-based triple-decker agar/sodium alginate/Ca2+ dual-network composite for wound dressing.

Directional Liquid Transport in Thin Fibrous Matrices: Enhancement of Advanced Applications.

Directional liquid transport fibrous matrices (DLTFMs) have the unique ability to direct liquid movement in a single direction through their thickness. Beyond their inherent liquid transport function, DLTFMs can also enhance the effectiveness of additional functionalities. This review focuses on recent advances in DLTFMs, particularly the role of DLTs in enhancing secondary functions. We begin with a brief overview of the historical development and major achievements in DLTFM research, followed by an outline of the classification, fabrication techniques, and basic functions derived from their natural liquid transport properties. The integration of DLT to enhance secondary functionalities such as responsiveness, thermal regulation, and wearable technology for innovative applications in various sectors is then discussed. The review concludes with a discussion of key challenges and prospects in the field, including the durability and reliability of DLT performance, the precise regulation of fluid transport rates, the resilience and longevity of DLTFMs in harsh environments, and the impact of DLT variations on performance enhancement. The goal of this review is to stimulate further innovative studies on DLTFMs and to promote their practical implementation in a variety of industries.

Direction-preferred liquid transportation on biomimetic hierarchical gradient microgrooves

Conventional understanding holds that droplets on microgrooves flow symmetrically toward both ends, which limits their utility in applications requiring direction-preferred droplet transport, such as vapor chambers. Inspired by the fog-collecting strategies of cactus spines, we propose a bioinspired hierarchical gradient microgroove (BHGM) that achieves the liquid transport in a preferred direction. By combining primary microgrooves with surface nanostructures, BHGM provides a strong initial driving force for liquid transport. Secondary microgrooves are introduced to increase the liquid–solid contact area, further enhancing capillary pressure. Additionally, gradient interfaces at structural discontinuities create unbalanced surface tension, driving direction-preferred liquid transport. This, in combination with the shape variation of the secondary grooves, regulates the meniscus and enables rapid and heterogeneous liquid movement. The BHGM demonstrates forward capillary wicking over a distance of up to 90 mm in just 12.5 s while reducing reverse wicking time by 53.7%. At the two gradient interfaces from bottom to top, speed reduction rates are only 7.7% and 2.3%, respectively. In addition, the BHGM maintains liquid transport capability even at bending angles of 90° and 120°. This hierarchical design enhances heterogeneous capillary transport efficiency while preserving scalability and adaptability, offering promising potential for practical applications, including improved thermal management in vapor chambers and more efficient fluid control in microfluidics.

Insight into the behavior and dynamics of extended thin films in shear-thinning liquids

Extended liquid thin films are essential and ubiquitous in the field of microfluidics. Mass and energy transfer in microfluidic systems, such as micro-scale heat pipes, falling film reactors, etc., depend on the forces acting near the three-phase contact line. Within the extended thin film region, the solid–liquid intermolecular force becomes significant along with the surface force. Several experiments have been conducted to understand and optimize the forces involved in mass and energy transport for Newtonian liquids. However, in real-world situations, these extended thin films are usually made of non-Newtonian liquids. The impact of high viscous forces and the complex rheology of non-Newtonian liquids on the extended thin film remains largely unexplored. This work pioneers a detailed experimental investigation into the extended thin film behavior of a shear-thinning polymeric liquid solution, offering new insights into this understudied phenomenon. The polymeric solution is supplemented with a surfactant to adjust the surface tension. The interplay between surfactant and the intrinsic nature of polymer solutions is studied by measuring their rheological properties. The extended thin film thickness is measured using image-analysis interferometry for polymer solutions with varying concentrations. The Hamaker constant is calculated from the slope and curvature profiles. A theoretical model is developed using the augmented Young–Laplace equation. The model can predict the extended film thickness profile near the three-phase contact line region. The model's predictions are favorably compared with experimental results. This work advances the understanding of extended thin film dynamics in non-Newtonian fluids, with broad implications for industrial and scientific applications.

Comparison of corrosion behavior of X52 steel in liquid and supercritical CO2 transport environments with multiple impurities

Comparison of corrosion behavior of X52 steel in liquid and supercritical CO2 transport environments with multiple impurities