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Upscaling of 1D two‐phase flows in heterogeneous porous media is important in interpretation of laboratory coreflood data, streamline quasi 3D modeling, and numerical reservoir simulation. In 1D heterogeneous media with properties varying along the flow direction, phase permeabilities are coordinate‐dependent. This yields the Buckley‐Leverett equation with coordinate‐dependent fractional flow f = f(s, x), which reflects the heterogeneity. So, an x‐dependency is considered to reflect microscale heterogeneity and averaging over x—upscaling. This work aims to average or upscale the heterogeneous system to obtain the homogenized media with such fractional flow function F(S) that provides the same water‐cut history at the reservoir outlet, x = 1. Thus, F(S) is an equivalent property of the medium. So far, the exact upscaling for 1D micro heterogeneous systems has not been derived. With the x‐dependency of fractional flow, the Riemann invariant is flux f, which yields exact integration of 1D flow problems. The novel exact solutions are derived for flows with continuous saturation profile, transition of shock into continuous wave, transition of continuous wave into shock, and transport in heterogeneous piecewise‐uniform rocks. The exact procedure of upscaling from f = f(s, x) to F(S) is as follows: the inverse function to the upscaled F(S) is equal to the averaged saturation over x of the inverse microscale function s = f −1(f, x). It was found that the Welge's method as applied to heterogeneous cores provides the upscaled F(S). For characteristic finite‐difference scheme, the fluxes for microscale and upscaled‐numerical‐cell systems, coincide in all grid nodes. Plain Language Summary Natural or industrial two‐phase flow of CO2, water and other fluids occurs in highly heterogeneous porous media. The flow dynamics is modeled by transport equations with highly oscillating coefficients, which require extensive computational resources. This study aims to develop an upscaling technique for the coordinate‐dependent flux resulting from the heterogeneity of the porous medium. The upscaling technique relies on the flux history (water‐cut) and saturation profiles across the porous medium. It is determined that, for a given sequence or configuration of numerical cells or laboratory core samples, the upscaling of the coordinate‐dependent flux is achievable by saturation averaging. It is observed that results from water‐cut based upscaling depend on length L while those of saturation profile‐based upscaling depend on the time interval T. Key Points Exact solutions for 1D two phase flow in heterogeneous porous media Implicit formula for upscaling of x‐dependent fractional flow function Flux‐history and saturation‐profile based upscaling yield the same equation for the upper‐scale fractional flow

In this paper, using hawthorn leaves as raw materials, the effect of extracting total flavonoids from hawthorn leaves by aqueous two-phase system (ATPS) combined with ultrasonic assisted was studied. Through single factor test and response surface method Box-Behnken design (response surface method, BBD), according to the regression equation, the optimal process conditions were obtained as follows: the ratio of solid to liquid 1:37, ultrasonic time 40 min, ultrasonic power 360 w, ultrasonic temperature 65°C, and the yield of flavonoids was 2.869±0.0004%. This study shows that ultrasound combined with aqueous two-phase system (ATPS) is an effective method to extract total flavonoids from hawthorn leaves.

This paper presents a new, generalized two‐phase debris flow model that includes many essential physical phenomena. The model employs the Mohr‐Coulomb plasticity for the solid stress, and the fluid stress is modeled as a solid‐volume‐fraction‐gradient‐enhanced non‐Newtonian viscous stress. The generalized interfacial momentum transfer includes viscous drag, buoyancy, and virtual mass. A new, generalized drag force is proposed that covers both solid‐like and fluid‐like contributions, and can be applied to drag ranging from linear to quadratic. Strong coupling between the solid‐ and the fluid‐momentum transfer leads to simultaneous deformation, mixing, and separation of the phases. Inclusion of the non‐Newtonian viscous stresses is important in several aspects. The evolution, advection, and diffusion of the solid‐volume fraction plays an important role. The model, which includes three innovative, fundamentally new, and dominant physical aspects (enhanced viscous stress, virtual mass, generalized drag) constitutes the most generalized two‐phase flow model to date, and can reproduce results from most previous simple models that consider single‐ and two‐phase avalanches and debris flows as special cases. Numerical results indicate that the model can adequately describe the complex dynamics of subaerial two‐phase debris flows, particle‐laden and dispersive flows, sediment transport, and submarine debris flows and associated phenomena. Key Points This paper presents a new, generalized and unified two‐phase debris flow model Includes non‐Newtonian viscous stress, virtual mass, generalized drag, buoyancy New model adequately describes complex two‐phase debris flow, sediment transport

An effective way to improve the formation of gas hydrate is to increase the gas-liquid contact area, which can also improve the gas-liquid heat and mass transfer efficiency. Designed a natural gas hydrate formation flow experimental device, and a set of folding pipes are the gas hydrate formation units. The folding pipe hydrate formation units are composed of many U-type pipes, which are the main carrier of hydrate formation. The gas-liquid flow law in the U-type pipe has the great significance on gas hydrate formation. The gas-liquid two phase flow in a single U-type pipe has been simulated by Fluent, gas distribution rule and flow characteristics in the U-type pipe has been investigated. The range of the entrance gas volume fraction is 0.1～0.6. Calculation results show that there is a certain degree of mixture between gas and liquid in the former straight section. The gas and liquid began to layer in the front of bend, the gas and liquid stratified obviously in the process of bend. The gas and liquid began to mix in the later straight section, but the degree of mixture is lower than the former. The liquid and gas flow phenomenon is different with disparate gas volume fraction. The gas and liquid stratified more obviously in the bend with the higher gas volume fraction. The law that the gas and liquid have a better mixture when gas volume fraction change range is 0.2～0.4 has been found, which is beneficial to hydrate formation.

We present an experimental and numerical study of immiscible two-phase flow of Newtonian fluids in three-dimensional (3D) porous media to find the relationship between the volumetric flow rate ( Q ) and the total pressure difference ( Δ P ) in the steady state. We show that in the regime where capillary forces compete with the viscous forces, the distribution of capillary barriers at the interfaces effectively creates a yield threshold ( P t ), making the fluids reminiscent of a Bingham viscoplastic fluid in the porous medium. In this regime, Q depends quadratically on an excess pressure drop ( Δ P - P t ). While increasing the flow rate, there is a transition, beyond which the overall flow is Newtonian and the relationship is linear. In our experiments, we build a model porous medium using a column of glass beads transporting two fluids, deionized water and air. For the numerical study, reconstructed 3D pore networks from real core samples are considered and the transport of wetting and non-wetting fluids through the network is modeled by tracking the fluid interfaces with time. We find agreement between our numerical and experimental results. Our results match with the mean-field results reported earlier.

The emergence of blockchains has fueled the development of resilient systems that deal with Byzantine failures due to crashes, bugs, or even malicious behavior. Recently, we have also seen the exploration of sharding in these resilient systems, this to provide the scalability required by very large data-based applications. Unfortunately, current sharded resilient systems all use system-specific specialized approaches toward sharding that do not provide the flexibility of traditional sharded data management systems. To improve on this situation, we fundamentally look at the design of sharded resilient systems. We do so by introducing ByShard , a unifying framework for the study of sharded resilient systems. Within this framework, we show how two-phase commit and two-phase locking —two techniques central to providing atomicity and isolation in traditional sharded databases—can be implemented efficiently in a Byzantine environment, this with a minimal usage of costly Byzantine resilient primitives. Based on these techniques, we propose eighteen multi-shard transaction processing protocols. Finally, we practically evaluate these protocols and show that each protocol supports high transaction throughput and provides scalability while each striking its own trade-off between throughput , isolation level , latency , and abort rate . As such, our work provides a strong foundation for the development of ACID-compliant general-purpose and flexible sharded resilient data management systems.

The main objective of the study is to propose a technical solution integrated into the pipeline for the transition of the flow regime from slug to bubbly two-phase flow. The object of research is isothermal two-phase gas–Newtonian-liquid flow in a horizontal circular pipeline. There is local resistance in the pipe in the form of a streamlined transverse mesh partition. The mesh partition ensures the transition of the flow from the slug regime to the bubbly regime. The purpose of the study is to propose a technical solution integrated into the pipeline for changing the flow regime of a two-phase flow from slug to bubbly flow. The method of research is a simulation using computational fluid dynamics (CFD) numerical simulation. The Navier–Stokes equations averaged by Reynolds describes the fluid motion. The k-ε models were used to close the Reynolds-averaged Navier–Stokes (RANS) equations. The computing cluster «Polytechnic—RSK Tornado» was used to solve the tasks. The results of simulation show that pressure drop on the grid did not exceed 10% of the pressure drop along the length of the pipeline. The mesh partition transits the flow regime from slug to layered one, which will help to increase the service life and operational safety of a real pipeline at insignificant energy costs to overcome the additional resistance integrated into the pipeline.

Hydrogen storage is a promising technology for storage of renewable energy resources. Despite its high energy density potential, the development of hydrogen storage has been impeded, mainly due to its significant cost. Although its cost is governed mainly by electrical energy expense, especially for hydrogen produced with alkaline water electrolysis, it is also driven by the value of the cell tension. The most common means of electrolyzer improvement is the use of an electrocatalyst, which reduces the energy required for electrochemical reaction to take place. Another efficient means of electrolyzer improvement is to use the Computational Fluid Dynamics (CFD)-assisted design that allows the comprehension of the phenomena occurring in the electrolyzer and also the improvement in the electrolyzer’s efficiency. The designed two-phase hydrodynamics model of this study has been compared with the experimental results of velocity profiles measured using Laser Doppler Velocimetry (LDV) method. The simulated results were in good agreement with the experimental data in the literature. Under the good fit with experimental values, it is efficient to introduce a new physical bubble transfer phenomenon description called “bubble diffusion”.

Multiphase flow and mineral reactions co‐exist in many subsurface systems, and thus elucidating and quantifying the impacts of multiphase flow on mineral reaction rates are crucial. Our study established a benchmark experiment on calcite dissolution in cylindrical pores in slug flow, and performed a series of simulations using a validated pore‐scale multiphase reactive transport model. The results revealed contrasting impacts of the two‐phase flow on transport in the aqueous phase and the effective surface area, and that the relative contribution of these factors determines whether the bulk reaction rate in two‐phase flow is lower (regime I) or higher (regime II) than that in single‐phase flow. Scaling laws were attempted to relate reaction rate with velocity to account for the enhanced transport by internal circulations, and variability in the effective surface area was also discussed. This study provides useful insights for upscaling mineral reaction rate in two‐phase flow in porous media.

Gas-liquid two-phase flow is widely used in various fields of chemical production because of its stability. The bubble coalescence behavior significantly impacts bubbles’ size, shape, and movement. These parameters are essential for interphase mass, heat transfer processes, and equipment performance. This paper presents a simulation study of the bubble coalescence behavior of Newtonian fluids using the phase field method through simulation software. The relative location of bubbles were divided into three types: vertical, parallel and random; and also the distribution of bubbles can be divided into three cases: symmetric, left-skewed and right-skewed. This paper focuses on the influence of the arrangements of the bubbles on their coalescence behavior in Newtonian fluids. The results show that the relative distance of bubbles is the crucial factor for the occurrence of bubble coalescence in Newtonian fluids, and different distributions show different laws on the motion of bubbles.