Fluid System Research Articles

Sloshing reduction in microgravity: Thermocapillary-based control and passive baffles

In this work, we numerically analyze different thermocapillary-based strategies for active control of sloshing in microgravity. The fluid system considered is an open rectangular container holding a L×H=30 × 15 mm2 volume of liquid. A classical controller is implemented to reduce the natural sloshing motion of the system, which is characterized by its decay time τd. The controller produces an output signal ΔT that is applied anti-symmetrically at the lateral walls of the container, driving thermocapillary flow. Its performance is characterized via the functional P=(1−λ) τ̂+λ κ̂, which allows for a trade-off between the damping of unwanted sloshing modes and the cost of implementing the control, with normalized decay time τ̂ and cost κ̂, and modulated by λ∈[0, 1]. We optimize P for discrete values of λ and determine the optimal performance envelope. The results show that thermocapillary controllers are generally able to reduce τd by a 50% factor, with reasonable cost and controller output. A novel strategy combining thermocapillary controllers and passive baffles is further proposed and assessed. On their own, passive baffles can reduce the natural decay time of sloshing by an 80% factor at zero cost. In addition, they significantly alleviate the thermal requirements associated with the control, while providing additional improvements in τd. Finally, the aforementioned strategies are tested against a reboosting maneuver of the International Space Station, showing their potential for sloshing reduction in microgravity.

Płuczki wiertnicze w skomplikowanych warunkach: przegląd

The review in this article focuses on various aspects of drilling extended reach (ERD) wells. Reaching extreme depths and setting world records for deviation illustrates the importance of well design and operating strategies. Studies of articles describing various locations, including Sakhalin Island in Russia and offshore Vietnam, provide insight into ERD operations. Furthermore, the challenges of drilling in specific geological conditions, such as layered sandstones and reactive clay, are considered. Particular attention is paid to issues related to wellbore instability and drilling fluid optimization. The results of technical studies highlight the key role of maintaining wellbore stability in achieving successful ERD results. The articles emphasize the importance of understanding geomechanical factors, employing optimal mud weight, lubrication, and specialized drilling fluids to counteract instability. It demonstrates that maintaining appropriate mud weights and employing specific drilling techniques are crucial for mitigating instability-related issues. The integration of mechanical and chemical approaches is advocated for effectively managing shale-related instability. The utilization of innovative materials and fluid systems is central to the successful resolution of stability-related problems. The incorporation of micronized sealing polymers in conjunction with conventional plugging materials is detailed as an effective approach to counter wellbore instability. The synergistic combination of materials, additives and mud salinity is showcased to achieve effective shale stabilization and optimize drilling time. The authors emphasize the importance of selecting the optimal composition for each well based on experience and laboratory testing and present laboratory-tested solutions that have been successfully applied in field operations. In summary, these articles collectively offer insights into a range of strategies to combat wellbore instability. They cover the use of advanced materials, innovative fluid systems, and chemical approaches to maintain wellbore stability, improve drilling efficiency, and reduce nonproductive time.

On Entropy Generation and Heat Transfer Due to Magneto-Marangoni Convective γ Al2O3-H2O/C2H6O2 Nanofluid Flow Over a Porous Surface

A numerical analysis is carried out for water/Ethylene Glycol based γ Al2O3 nanofluid movement over a horizontal permeable sheet placed within a porous medium using MATLAB package Bvp4c solver. Other flow controlling conditions like Non-linear thermal radiation and uniform Magnetic field are also considered for this study. The present study is novel in terms of entropy generation and heat transfer rate investigation for mentioned fluid system in the existence of dissipation (an irreversible process) and heat generation/absorption impact. First, a mathematical pattern is prepared in the form of partial differential equations to represent the Marangoni convection flow and temperature, considering suitable boundary conditions. Using similarity parameters, we convert our mathematical model in dimensionless form and then solved it. Accuracy of obtained data is also cross-checked with another numerical technique “Runge-Kutta fourth order” along with shooting process. Using velocity and temperature fields, entropy is measured for present system. From the plots, it is noted that entropy as well as Bejan number is qualitatively changed for parameters namely, volume fraction parameter, radiation parameter, Brinkmann number and heat generation/absorption parameter. It is noticed that heat transfer rate and entropy generation number is higher for γ Al2O3-C2H6O2 nano fluid then γ Al2O3-H2O nano fluid.

Nonlocal phase coupling in turbulence spreading across the magnetic island

We study the nonlocal phase coupling during turbulence spreading across the magnetic island. It is found that the coherent convective cells (sharing similar features to quasi-coherent mode in experiment) on both sides of the O-point boundary are accumulated during the island formation. The phase entrainment of the convective cells on the turbulence both in the inner and the outer regions of the magnetic island sets up a nonlocal phase coupling channel and leads to a fast spreading of the outer turbulence into the magnetic island by conquering the flow shear at the O-point boundary. This nonlocal coupling mechanism of turbulence spreading is analogous to a turbulence version of the well-known enhanced diffusion of passive scalars in laminar convective flows of neutral fluid system.

Viscous effects on morphological and thermodynamic non-equilibrium characterizations of shock–bubble interaction

A two-fluid discrete Boltzmann model with a flexible Prandtl number is formulated to study the shock–bubble interaction (SBI). This paper mainly focuses on the viscous effects on morphological and thermodynamic non-equilibrium (TNE) characterizations during the SBI process. Due to the rapid and brief nature of the SBI process, viscosity has a relatively limited influence on macroscopic parameters but significantly affects the TNE features of the fluid system. Morphologically, viscosity affects the configuration of the vortex pair, increases both the amplitudes of gradients of average density and average temperature of the fluid field, and reduces circulation of the bubble. As a higher viscosity fluid absorbs more energy from the shock wave, it leads to an increase in both the proportion of the high-density region and the corresponding boundary length for a fixed density threshold. The spatiotemporal features of TNE quantities are analyzed from multiple perspectives. The spatial configuration of these TNE quantities exhibits interesting symmetry, which aids in understanding the way and extent to which fluid unit deviates from the equilibrium state. Theoretically, viscosity influences these TNE quantities by affecting the transport coefficients and gradients of macroscopic quantity. Meanwhile, the viscosity increases the entropy production rate originating from the non-organized momentum flux mainly through amplifying the transport coefficient and enhances the entropy production rate contributed by the non-organized energy flux by raising the temperature gradient. These multi-perspective results collectively provide a relatively comprehensive depiction of the SBI.

Size Controllable Micro-nano Fluidic Systems Based on Various Angle Sputtering Deposition

Micro-nano fluid systems are widely used in biochemistry and are important to MEMS research. For the fabrication of microfluidic systems, controllable size nanochannels have always been a research challenge. This article proposes a method for fabricating nanochannels based on angle deposition, which can regulate channel size at tens of nanometers. At the same time, DNA molecular stretching simulations and experiments were conducted to verify the application prospects of the sample in the biological field.

Particle-resolved direct numerical simulation of particle-laden turbulence modulation with high Stokes number monodisperse spheres

Graphic processing units (GPU)-accelerated direct numerical simulations of particle–fluid systems based on lattice Boltzmann method combined with discrete element method are successfully performed. This method is validated to be accurate and efficient in the four-way coupling simulation of particle–fluid systems. Particle-laden homogeneous isotropic turbulence under particle size dp=30.1η (the Kolmogorov length scale), a wide range of solid volume fraction ϕV=2%−20% and particle Stokes number St=503.87−50 387 are systematically studied. The additional energy dissipation rate εaddi induced by particles is quantitatively calculated. One criterion for turbulence enhancement or attenuation based on energy balance is proposed and successfully used in different particle-laden turbulence. The relative magnitude of two-way coupling rate ψ and particle-induced dissipation εaddi is the direct factor determining the modulation effect on turbulence. Turbulence laden with high Stokes number particles is enhanced. Turbulence laden with high volume fraction particles transited rapidly from enhancement to attenuation, which is attributed to the more rapid decay of ψ relative to εaddi in the freely decaying turbulence.

A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid

Three high-temperature resistant polymeric additives for water-based drilling fluids are designed and developed: weakly cross-linked zwitterionic polymer fluid loss reducer (WCZ), flexible polymer microsphere nano-plugging agent (FPM) and comb-structure polymeric lubricant (CSP). A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid was developed for deep drilling. The WCZ has a good anti-polyelectrolyte effect and exhibits the API fluid loss less than 8 mL after aging in saturated salt environment at 200 °C. The FPM can reduce the fluid loss by improving the quality of the mud cake and has a good plugging effect on nano-scale pores/fractures. The CSP, with a weight average molecular weight of 4804, has multiple polar adsorption sites and exhibits excellent lubricating performance under high temperature and high salt conditions. The developed drilling fluid system with a density of 2.0 g/cm3 has good rheological properties. It shows a fluid loss less than 15 mL at 200 °C and high pressure, a sedimentation factor (SF) smaller than 0.52 after standing at high temperature for 5 d, and a rolling recovery of hydratable drill cuttings similar to oil-based drilling fluid. Besides, it has good plugging and lubricating performance.

Multi-layer Rayleigh–Taylor instability: Consequences for naturally occurring stratified mixing layers

The present study investigates the behavior of multi-layer Rayleigh–Taylor instability (RTI) and enstrophy transport in the flow using a three-dimensional computational framework. The dynamics of RTI are explored in a monotonically unstable stratified fluid system composed of air at different constant temperatures, initially separated by insulating partitions. Our results illustrate the formation of a multi-layer RTI system and the growth of convective mixing layers from interfaces between consecutive layers. The behavior of single-layer and multi-layer RTI is compared by considering the influence of Atwood numbers on growth and characteristics of the mixing layers. We found that the presence of multiple layers affects the onset and development of RTI. The merging of top layers leads to accelerated mixing layer growth, while the bottommost layer experiences early-stage RTI. Furthermore, we utilize the compressible enstrophy transport equation to characterize dominant mechanisms controlling the spatiotemporal evolution of the multi-layer RTI. The results highlight the significance of viscous and compressibility terms, especially in the center. In contrast, the vortex stretching term dominates near side walls for later stages of the RTI. These insights enrich the understanding of multi-layer RTI and its effects on enstrophy transport and mixing in unstably stratified fluid systems, providing valuable data for validating numerical methods and informing future research in related fields.

The main features of compositional modeling algorithms of modern reservoir flow simulators

Modern industrial reservoir flow simulators are integrated software products consisting of several packages. Modeling of gas injection with various compositions, or hydrocarbon recovery from gas-condensate and oil-gas-condensate reservoirs, or thermal recovery methods requires a detailed account for composition of the fluid system. In these cases, compositional (multi-component) flow simulation is used to calculate component distribution between the coexisting phases, the number and the fractions of the phases, together with the flow equations for fluid components.. For this purpose, the flow simulator solves the thermodynamic subproblem using basic methods and algorithms analogous to the fluid modeling (PVT modeling) packages. The paper describes the main principles and specific features of implementation of the compositional modeling algorithms in several modern reservoir flow simulators. Keywords: compositional modeling; multicomponent flow model; reservoir flow simulator; isothermal and non-isothermal compositional modeling.

Dynamic mode decomposition with memory.

This study proposed a numerical method of dynamic mode decomposition with memory (DMDm) to analyze multidimensional time-series data with memory effects. The memory effect is a widely observed phenomenon in physics and engineering and is considered to be the result of interactions between the system and environment. Dynamic mode decomposition (DMD) is a linear operation-based, data-driven method for multidimensional time-series data proposed in 2008. Although DMD is a successful method for time-series data analysis, it is based on ordinary differential equationsand thus cannot incorporate memory effects. In this study, we formulated the abstract algorithmic structure of DMDm and demonstrate its utility in overcoming the memoryless restriction imposed by existing DMD methods on the time-evolution model. In the numerical demonstration, we utilized the Caputo fractional differential to implement an example of DMDm such that the time-series data could be analyzed with power-law memory effects. Thus, we developed a fractional DMD, which is a DMD-based method with arbitrary (real value) order differential operations. The proposed method was applied to synthetic data from a set of fractional oscillators and model parameters were estimated successfully. The proposed method is expected to be useful for scientific applications and aid in model estimation, control, and failure detection of mechanical, thermal, and fluid systems in factory machines, such as modern semiconductor manufacturing equipment.

Experimental Study of a One-Step Multifunctional Treatment Fluid for Water-Based Mud Filter-Cake Cleanup

Summary Filter-cake cleanup following the drilling and completion operation is important for reestablishing communication between the formation and wellbore. A dual-action cleanup system for water-based mud (WBM) was developed to dissolve the calcium carbonate (CaCO3) bridging agent and polymeric materials present in the filter cake. The novel treatment fluid contains a high concentration of nonencapsulated oxidizing salts and delayed acid generating materials and is gelled with a viscoelastic surfactant (VES)-based surfactant. The fluid provides many advantages over traditional fluids as it does not generate any residue on breaking, unlike the traditional polymeric gelling agent. The breakage or reduction in viscosity of this fluid can be accomplished by contact with the produced oil thereby disrupting the micelles. Traditional polymers on the other hand are broken by oxidizers, and if delayed breakage is desired, the breaker needs to be encapsulated. Another benefit of this system is that the VES gelation may enhance uniform filter-cake cleanup in extended reach horizontal sections of the wellbore. The novel fluid system contains a strong oxidizer, namely, sodium bromate (NaBrO3), that activates at temperatures above 160oF causing the breakdown of the polymer contained within the filter cake without affecting the VES surfactant or gelation which helps in mixing the fluid at the surface. Finally, the fluid contains an acid-generating precursor that is neutral at ambient temperature conditions. Once the fluid is heated up in the formation, acid is generated via ammonium oxidation, thereby lowering the viscosity of the gel and dissolving the CaCO3 bridging material. In summary, the fluid that can be prepared on the fly accomplishes multiple functions ranging from controlled gelation to clean break without residue or outside intervention to dissolution and degradation of inorganic and polymeric components.

Applicability of sawdust as a green additive to improve the rheological and filtration properties of water-based drilling fluid: an experimental investigation

Drilling fluid is essential to oil and gas drilling operations due to its diverse functionality. But the most commonly used drilling fluid additives are hazardous chemicals and are not biodegradable. As a result, the demand for environment-friendly additives has been raised to replace the hazardous chemical additives. Considering the rising interest toward green additive, this study examined the applicability of sawdust to be used as a biodegradable drilling fluid additive to improve the rheological and filtration properties of water-based mud. Sawdust was chosen for this study because of its high cellulose content, widespread availability, and low cost. Following the guidelines set by the American Petroleum Institute (API), we carried out laboratory experiments that encompassed three distinct concentrations of sawdust: sample 1 (with 0.25% sawdust), sample 2 (with 0.50% sawdust), and sample 3 (with 0.75% sawdust). The concentrations of sawdust were measured as a weight percentage of the total volume of the base water. Concentrations above 0.75% led to gelation issues. Results showed minimal impact on mud weight at 0.25% sawdust, while 0.50 and 0.75% concentrations caused slight weight reduction due to foam development. Plastic viscosity increased by 28.5, 42.8, and 71.4% for sample 1, sample 2, and sample 3, respectively, compared to the base mud. Sawdust-containing mud exhibited desirable gel strength and shear-thinning behavior. Moreover, sawdust significantly improved filtration properties by reducing fluid loss and mud cake thickness. Sample 2 (0.5% sawdust) performed well in terms of filtration properties. Mud cake permeability followed the trend: kBM>k0.75%sawdust>k0.25%sawdust>k0.50%sawdust\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${k}_{\\mathrm{BM}}>{k}_{0.75\\% \\mathrm{sawdust}}>{k}_{0.25\\% \\mathrm{sawdust}}>{k}_{0.50\\% \\mathrm{sawdust}}$$\\end{document}. Based on promising laboratory performance, lower concentrations of sawdust are recommended as a cost-effective and eco-friendly additive to enhance rheological and filtration properties of water-based drilling fluid systems.

Comprehensive Study of Synergistic-Dual-Functional Mechanism of Kinetic and Thermodynamic Inhibitors in a Hydrate Drilling Fluid System

Comprehensive Study of Synergistic-Dual-Functional Mechanism of Kinetic and Thermodynamic Inhibitors in a Hydrate Drilling Fluid System

Solitary-Wave Solutions of Benjamin–Ono and Other Systems for Internal Waves: II. Dynamics

Considered here are two systems of equations modeling the two-way propagation of long-crested, long-wavelength internal waves along the interface of a two-layer system of fluids in the Benjamin–Ono and the Intermediate Long-Wave regime, respectively. These systems were previously shown to have solitary-wave solutions, decaying to zero algebraically for the Benjamin–Ono system, and exponentially in the Intermediate Long-Wave regime. Several methods to approximate solitary-wave profiles were introduced and analyzed by the authors in Part I of this project. A natural continuation of this previous work, pursued here, is to study the dynamics of the solitary-wave solutions of these systems. This will be done by computational means using a discretization of the periodic initial-value problem. The numerical method used here is a Fourier spectral method for the spatial approximation coupled with a fourth-order, explicit Runge–Kutta time stepping. The resulting, fully discrete scheme is used to study computationally the stability of the solitary waves under small and large perturbations, the collisions of solitary waves, the resolution of initial data into trains of solitary waves, and the formation of dispersive shock waves. Comparisons with related unidirectional models are also undertaken.

A study of non-equilibrium wave groups in two-phase flow in high-contrast porous media with relative permeability hysteresis

Non-equilibrium models are applicable in various physical situations, including phase transitions, hysteresis, and chemical reactions, among others. To model the dynamics of such phenomena, partial differential equations are employed with source terms, as seen in Eq. (1.1). This work focuses on situations where we connect states in equilibrium while allowing for non-equilibrium times. In our model, we model non-equilibrium through relaxation. The source term, in this case, acts as an attractor, and the model’s dynamics allow only a small-time far from equilibrium. We use this theory to model a two-equation system in a two-phase fluid in porous media, where different permeabilities of the flow lead to hysteresis phenomena. We show several examples and study the Riemann solution to gain a better understanding of the solution. We investigate the interplay between nonlinear wave groups of water–oil saturation with different permeabilities in the non-wetting phase and the high-contrast heterogeneity of the porous medium in two-space dimensions. This phenomenon is described by a coupled set of time-dependent partial differential equations of hyperbolic–parabolic–elliptic mixed type. We present and discuss a new projection method with relaxation to obtain 1D-analytical Riemann solutions in an idealized homogenized medium, and we use this solution to validate our numerical method. The primary components of obtaining these solutions are shocks, rarefactions, and bifurcations. We obtain 2D-numerical solutions using an operator splitting approach based on physics, highlighting the discretization methods used. We provide robust analytical–numerical examples to verify the theory and illustrate the approach’s capabilities. In particular, we discuss the 1D-2D behavior of wave groups in situations driven by water–oil infiltration problems of permeable reservoir rocks.

Sensitivity Evaluation and Stimulation Optimization of Ultralow Permeability Sandstone Reservoir.

Acidizing operation is normally applied in low permeability reservoirs, but if the acid system is not utilized properly, it will cause sensitive damage to the reservoir. As for the Sanjianfang Formation of the sandstone reservoir in the Shanshan oilfield, the problems existing in acidizing are especially serious. For these problems, the basic characteristics, sensitivity characteristics, and damage mechanisms were obtained by means of X-ray diffraction (XRD) analysis and scanning electron microscopy. Meanwhile, gas porosity and permeability were measured, and reservoir sensitivity characteristics were evaluated. The results showed that the reservoir rocks are mainly feldspar lithic sandstone and the clay minerals are mainly kaolinite and montmorillonite, which belong to the high clay mineral reservoir. It is an unsaturated reservoir with normal formation pressure that has low porosity and ultra-low permeability, heavy crude oil, and low porosity. The reservoir is highly stress sensitive, moderately weak velocity sensitive, alkali sensitive, water sensitive, salt sensitive, and weak acid sensitive. Based on these results, a multinanoscale stimulating liquid system was developed in the laboratory, and field application of this fluid system combined with mud acid was carried out. The combination system of multinanoscale highly efficient stimulation fluid and mud acid can meet the optimal dissolution rate of rock during the acidizing process and can increase the permeability of the targeted reservoir by 2.68 times, with a remarkable field application effect. The research results can provide a scientific basis for acidizing and stimulation of ultralow permeability sandstone reservoir.

Waterlike density anomaly in fermions

In this work we explore the one-dimensional extended Hubbard model as a fluid system modeling liquid phases of different densities. This model naturally displays two length scales of interaction, which are connected with waterlike anomalies. We analyze the density anomaly as a function of the model parameters, namely the hopping, on-site and first neighbor interactions. We show that this anomaly is present for a wide range of model parameters and is connected to a ground-state liquid–liquid critical point.

Three-Dimensional Scaffolds for Intestinal Cell Culture: Fabrication, Utilization, and Prospects.

The intestine is a visceral organ that integrates absorption, metabolism, and immunity, which is vulnerable to external stimulus. Researchers in the fields such as food science, immunology, and pharmacology have committed to developing appropriate in vitro intestinal cell models to study the intestinal absorption and metabolism mechanisms of various nutrients and drugs, or pathogenesis of intestinal diseases. In the past three decades, the intestinal cell models have undergone a significant transformation from conventional two-dimensional cultures to three-dimensional (3D) systems, and the achievements of 3D cell culture have been greatly contributed by the fabrication of different scaffolds. In this review, we first introduce the developing trend of existing intestinal models. Then, four types of scaffolds, including Transwell, hydrogel, tubular scaffolds, and intestine-on-a-chip, are discussed for their 3D structure, composition, advantages, and limitations in the establishment of intestinal cell models. Excitingly, some of the in vitro intestinal cell models based on these scaffolds could successfully mimic the 3D structure, microenvironment, mechanical peristalsis, fluid system, signaling gradients, or other important aspects of the original human intestine. Furthermore, we discuss the potential applications of the intestinal cell models in drug screening, disease modeling, and even regenerative repair of intestinal tissues. This review presents an overview of state-of-the-art scaffold-based cell models within the context of intestines, and highlights their major advances and applications contributing to a better knowledge of intestinal diseases. Impact statement The intestine tract is crucial in the absorption and metabolism of nutrients and drugs, as well as immune responses against external pathogens or antigens in a complex microenvironment. The appropriate experimental cell model in vitro is needed for in-depth studies of intestines, due to the limitation of animal models in dynamic control and real-time assessment of key intestinal physiological and pathological processes, as well as the "R" principles in laboratory animal experiments. Three-dimensional (3D) scaffold-based cell cultivation has become a developing tendency because of the superior cell proliferation and differentiation and more physiologically relevant environment supported by the customized 3D scaffolds. In this review, we summarize four types of up-to-date 3D cell culture scaffolds fabricated by various materials and techniques for a better recapitulation of some essential physiological and functional characteristics of original intestines compared to conventional cell models. These emerging 3D intestinal models have shown promising results in not only evaluating the pharmacokinetic characteristics, security, and effectiveness of drugs, but also studying the pathological mechanisms of intestinal diseases at cellular and molecular levels. Importantly, the weakness of the representative 3D models for intestines is also discussed.

Synthesis and performance evaluation of a micron-size silica-reinforced polymer microsphere as a fluid loss agents

A silica-reinforced polymer microsphere was prepared by reverse suspension polymerization using acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and silica nanoparticles modified with methacryloyloxypropyltrimethoxysilane as a filtrate reductant resistant to high temperature and salt contamination. The filtration volume of American Petroleum Institute (API) sodium-based bentonite fluids was reduced by 63.5% after aging with the addition of 3.0 wt% M-SiO2/ZMD at 150 °C. M-SiO2/ZMD also exhibited significant salt resistance when compared to ZMD. The test results demonstrate that M-SiO2/ZMD exhibits excellent rheological and filtration properties even at elevated temperatures. A significant filtration reduction effect was also shown in the water-based drilling fluid system. The filtrate volumes before and after aging at 150 °C were 5.2 mL and 5 mL, respectively, when the addition amount was 1.0 wt%. Finally, the possible filtration loss reduction mechanisms involved in M-SiO2/ZMD are also discussed. This study provides a new heat- and salt-resistant fluid loss reduction material for water-based drilling fluids in oilfields, and provides theoretical support for its practical application.