Observed Flow Regimes Research Articles

Symmetrical vortices and laminar dust flow induced by an intense electron beam interacting with a strongly coupled dusty plasma

A strongly coupled quasi-two-dimensional dusty plasma confined electrostatically in the plasma sheath of a radio frequency (RF) plasma is irradiated by a collimated and mono-energetic pulsed electron beam (e-beam) with an energy of 13 keV and a high peak current per pulse of 30 mA. A stream of rapidly moving charged dust particles is created inside the dust crystal due to the drag force of the electrons in the e-beam. The dust flow is split into two symmetrical branches when it reaches the boundary of the round dust crystal, each following the limit of the circular confining region. This results in the formation of a double vortex flow pattern with the dust particles being transported along the irradiation direction and then aside, eventually back to the entrance position of the e-beam. The observed flow regime is laminar at all times, with the speed in the central region increasing up to 12 mm s−1 in the first 200 ms and then diminishing gradually to a steady value of about 5–6 mm s−1 during a stress relaxation time period of 360 ms. The vorticity follows a similar trend with peak values −3.8 and 3.8 s−1 and steady state values between −2.5 and 2.5 s−1 in the two symmetrical vortices. Time-resolved particle-image-velocimetry and particle-tracking-velocimetry are used to characterize the flow. Molecular dynamics simulations confirm qualitatively the experimental observations showing dust stream and double vortex formation.

An experimental study of dynamic flashing in a square tube using tap water

Flashing is a pressure driven phase change phenomenon. It is widely studied due to its richness in physics and applications such as in desalination, in nuclear industry to name a few. Dynamic flashing is a situation wherein the pressure drop for flashing is initiated through the flow of liquid. A recently developed novel desalination system [1] utilizes combined dynamic flashing and vapor separation through tangential injection for producing potable water. An understanding of dynamic flashing in a tube with reference to the novel desalination system could help with its optimization. In this work, dynamic flashing of tap water occurring in a clear quartz square tube was studied. The pressure and temperature measurements along the tube were made and analyzed for different inlet flowrates and initial liquid temperatures. The pressure and temperature values showed increasing gradients along the tube indicating increased vapor production or flashing for increasing flowrates and initial liquid temperatures. The vapor production from flashing and the resulting flow regimes along the tube were tracked and identified through high-speed imaging. Visual observations showed complex flow regimes with bubbles nucleating and growing throughout the tube due to flashing. Most of the bubble formation was observed in the bulk with little nucleation on the glass tube wall. Void fraction measurements along the tube based on capacitance impedance technique were performed to supplement the visual observations which showed increasing void fraction along the tube matching the observed flow regimes from vapor production.

Dry, drier, driest: Differentiating flow patterns across a gradient of intermittency

AbstractIntermittent streams exhibit regular patterns of drying and are widespread, but the patterns of drying among streams within geographic proximity are not fully understood. We compared annual patterns of flow and drying among 10 intermittent streams within a single drainage basin and assessed how traditional hydrologic metrics described variation between streams. We installed stream intermittency sensors and evaluated stage height using low‐cost methods and evaluated landscape factors as potential drivers of flow patterns. Intermittent streams varied based on both high‐ and low‐flow metrics, driven by a variety of landscape‐level factors, especially watershed size. Additionally, we compared the observed flow regimes within our system with predictions generated using an established Soil and Water Assessment Tool, finding that modeled streamflow patterns generally underrepresented observed drying within the system.

Vertically downward gas-liquid flow: Void fraction and pressure drop

Using an air-water mixture and 34 mm ID pipe, a series of pressure drop and void fraction measurements were collected. The observed flow regimes were falling film, annular, bubbly, cap bubble, slug, and churn flows. The temporal fluctuations of void fraction and pressure drop measurements were firstly studied using signals visualization and PDF. It was revealed that both signals can be used to identify the flow regimes. A new flow pattern map is proposed based on the Froude number, calculated using the mixture velocity of the two phases, and the ratio of gas-to-liquid superficial velocities. The behaviors of the total and frictional pressure drops were studied and the influence of the superficial velocities as well as the flow regimes were identified. The experimental results were compared to four existing vertically downward frictional pressure drop models, none of which provided accurate predictions.

Experimental and OLGA Modeling Investigation for Slugging in Underwater Compressed Gas Energy Storage Systems

Underwater compressed gas energy storage (UW-CGES) holds significant promise as a nascent and viable energy storage solution for a diverse range of coastal and offshore facilities. However, liquid accumulation in underwater gas pipelines poses a significant challenge, as it can lead to pipeline blockages and energy transmission interruptions and adversely impact pipeline operation. In this paper, experimental and Oil and Gas Assays (OLGA) simulation studies have been conducted on the formation process of slug flow in pipelines. Firstly, experiments are conducted to capture high-speed camera images of slug flow under various liquid accumulation volumes and inclination angles. Subsequently, an OLGA model is developed to verify the experimentally observed flow regime, pressure, and slugging speed. Therefore, the flow regime verification results exhibit substantial consistency, and pressure variations display uniform trends, with an average slugging velocity error of 6.42%. The results indicate that the formation of slug flow involves three distinct stages: slug flow growth, ejection, and backflow. By analyzing slug flow, it can gain insights into the relationship between pressure and slug flow formation, exposing the sensitivity of this phenomenon to pressure fluctuations. These results further enhance recognition of the operational status of UW-CGES pipelines and provide support for safe operation.

A detailed experimental evaluation of gas –Liquid film attributes in a horizontal rectangular duct by Planar Laser-Induced fluorescence (PLIF) approach

In the current experimental research, we aimed to discover the interfacial behavior of gas–liquid stratified two-phase flow sub-regime by the Planar Laser-Induced Fluorescence (PLIF) method. The introduced research was conducted in a horizontal stratified flow rectangular channel, where respected flow measurements were studied using some quantitative values established visually by obtained PLIF photographs. Moreover, applied indicators in the current study focus on each of the following factors:wave dynamics, liquid film thickness, flow velocities, and frequencies of film disruption waves. Meanwhile, in order to strain the experimental efforts in the study, film thickness measurements were examined in both space and time domains. In addition, integral data supplemented against loaded spatiotemporally recovered information on interface position and two-phase velocity fields collected using planar laser generated fluorescence (PLIF).The presented study ascertains a novel relationship between dimensionless description of wave velocity, film thickness, and frequency for the liquid film. The study was performed under gas shear with inlet water Reynolds values from 88 to 437, and air Reynolds numbers ranging from 6.95 to 34.8 x103. Experimental studies concluded that different modes of wave generation with a decrement in the wave speed, film thickness, and frequency increased at a specific liquid velocity, with increasing the superficial speed. According to the findings, the experimental and theoretical values of the attendance indicators four recognized stratified flow sub-regimes presented in the results, based on both Navier-Stokes, and Kosky models. The observed flow regimes were the Ripple wave, roll wave, Jeffrey wave, and random disturbance wave. Regarding wave frequency studies, the Azzopardi and Bae models used to compare wave frequency, while the Gawas and Sarkhi models were implemented to compare wave velocity.

Convective Flow in Nanoparticle Suspension Generated around a Photothermal Bubble

A microbubble generated by the laser beam’s photothermal conversion induces convective flow by the Marangoni effect at the gas-liquid interface. This flow is useful for the transport and accumulation of nanoparticles in liquid. This study investigates the regime of the convective flow in nanoparticle suspension around the generated microbubble. The empirically observed flow regime was initially similar to that of theoretically predicted convection in pure water, which has a circulating flow driving particles 100 μm away from the microbubble. However, after 10 ms of the laser heating, the size of the circulating flow decreased to the same as the bubble diameter. Additionally, a numerical simulation also shows that the decreasing of the circulating flow is observed when the driving force at the interface is limited to the shear stress of > 140 N/m2.

Flow regimes in a very wide-gap Taylor-Couette flow with counter-rotating cylinders.

In this study, we discuss the observed flow regimes in Taylor-Couette flow of radius ratio [Formula: see text] for various Reynolds numbers up to [Formula: see text]. We investigate the flow using a visualization method. The flow states in the centrifugally unstable flow are investigated in the case of counter-rotating cylinders and pure inner cylinder rotation. Beside classical known flow states as Taylor-vortex flow and wavy vortex flow, we observe a variety of new flow structures in the cylindrical annulus, especially for the transition to turbulence. Coexisting turbulent and laminar regions inside the system are observed. Turbulent spots and turbulent bursts are observed, as well as an irregular Taylor-vortex flow and non-stationary turbulent vortices. Especially, a single axially aligned columnar vortex between the inner and outer cylinder is found. The principal regimes observed in flow between independently rotating cylinders are summarized in a flow-regime diagram. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (Part 2)'.

Gas relative permeability evaluation in tight rocks using rate-transient analysis (RTA) techniques

The evaluation of effective and relative gas permeability is critical for modeling hydrocarbon recovery from low-permeability (unconventional) reservoirs, and for evaluating the potential for clean energy pathways such as carbon capture and sequestration and hydrogen storage in subsurface. Nevertheless, due to the low flow rates and long experimental times associated with low-permeability (nanodarcy/microdarcy range) sample testing, measuring relative permeability through conventional techniques is technically challenging, time-consuming, and expensive. Additionally, and importantly, none of the routine laboratory techniques for measuring relative permeability can mimic the boundary conditions under which wells are produced from, or injected into, in the field.For the first time, effective and relative gas permeability of partially-saturated low-permeability sedimentary rocks were investigated using state-of-the-art core analysis techniques based on rate-transient analysis (RTA). Conventional and new straight-line analysis methods, commonly applied to production data in the field, were used to estimate effective gas permeability of core plugs under variable stress conditions and water saturations. Five low-permeability siltstone and organic/clay-rich samples, differing in mineralogy, porosity, and pore size distribution, were analyzed for proof-of-concept testing.The observed flow regimes consist of transient linear flow followed by boundary-dominated flow regimes, as previously reported for field data. Satisfactory correlation (average coefficient of variation less than 7%) between permeability estimates using different RTA techniques demonstrates the applicability of this method for effective and relative permeability assessment of partially-saturated ultra-tight reservoirs (down to less than 1.0∙10−5 md). Importantly, test times after the initiation of the production phase, were on the order of minutes, which is significantly shorter than those commonly achievable using conventional techniques (e.g., hours using pulse-decay gas permeability testing). Effective gas permeability (from 1.5∙10−3 to 7.5∙10−6 md), and slip factor (from 715 to −286 psia−1), decreased with increasing water saturation (0–53%), reflecting the lower contribution of slip flow to gas transport. Effective gas permeability decreased with increasing effective stress (500–4000 psia), likely due to reduced effective (transport) pore throat size and increased tortuosity. The reduction of slip factor and the observed stress dependency with water saturation is attributed to the channel flow mechanism.

Flow regime transitions for Aiding flow around a heated cylinder: A numerical and experimental investigation

Experiments and numerical simulations were performed to examine the interplay between buoyancy and momentum effects for mixed convection flow around a 13.4 mm diameter cylinder in water. PIV and LIF measurements were made to obtain experimental velocity and temperatures over a Ri range from 0 to 9. LES models were validated against the measured experimental conditions and then used to numerically study the parametric behaviour over a wider range of conditions. The CFD model was found to perform well, with a small tendency to over predict temperature and velocity measurements for higher buoyancy conditions, Ri > 1.9. Using the experimental LIF results, three flow regimes around the cylinder were identified, grouped, and made into a flow regime map. From this, two sets of transition criteria were developed and proposed to predict the collapse of the recirculation zone and the total suppression of vortex formation. This was done via observations from the experimental data and additional CFD simulations to examine the separate effects of fluid properties and incident turbulence levels, both of which were shown to influence vortex suppression significantly. The criteria proposed was found to accurately capture the visually observed flow regimes experimentally in water.

Developing adiabatic two-phase flow after an expansion valve: Flow development in an 8 mm tube

This paper presents the developing two-phase flow after an expansion valve. R134a with 1.3% POE32 is used as a working medium. The flow patterns are visualized from 15 mm until 595 mm after the expansion valve in a straight tube with an inner diameter of 8 mm. The experiments cover the mass flux from 100 to 480 kg m−2 s−1 and the range of quality from 0.002 to 0.500. The observed flow patterns are classified into four regions as two-phase flow progresses along the tube: well-mixed, separating, separated but developing, and fully developed. Due to the sudden expansion in TEV, the flow structure in the well-mixed region is similar to homogeneous flow, with bubbles or droplets dispersed uniformly. Then, the gravity/buoyancy force becomes more dominant over inertia and surface tension because of the reduction of liquid velocity and the growth of bubbles. Consequently, bubbles migrate upwards while droplets fall downward, characterizing the separating region. After phase separation, the flow characteristics may still change for a certain distance before the flow is fully developed. Based on the observed flow regimes at various working conditions, a 3D flow pattern map is built, adding the distance from the expansion valve as the third dimension besides the mass flux and quality. In a following paper, the authors will discuss the effect of tube diameter, oil, and structure of expansion devices on developing two-phase flow. The developed flow patterns will be compared with the existing flow pattern map in steady conditions as an asymptote.

Immersed buoyant viscoplastic injections

In this study, the injection of a viscoplastic (yield stress) fluid into a quiescent Newtonian medium is experimentally investigated, using a range of experimental methods, including high-speed camera imaging, laser-induced fluorescence (LIF), and ultrasound Doppler velocimetry (UDV) techniques. The case of our consideration is the continuous downward injection of a Carbopol solution, as a core fluid, through an eccentric inner pipe, placed inside a vertical closed-end pipe filled with a glycerin–water solution. The injected fluid is always heavier than the in-situ fluid and the fluids are miscible. As the injection continues, a filament of the core fluid immersed in the in-situ fluid is formed, for which it has been shown that there exist three distinct flow patterns, namely, the breakup, coiling, and bulging (buckling) regimes. Our focus in this study is to analyse the detailed flow features and sub-regimes at longer times, from an experimental perspective. To generalize our results, they are presented versus the governing dimensionless numbers of the flow, i.e. the buoyancy number, the Bingham number, the viscosity ratio, and the falling height. The breakup regime is analysed in terms of the yielding, necking and pinch-off process, the length of filaments, and their subsequent falling behaviours, the coiling regime in terms of the regular, free and irregular coiling behaviours, and the bulging (buckling) regime in terms of the appearance of a detached falling part and the maximum penetration depth. The results of this work can find applications, in particular, in the plug and abandonment (e.g. cementing processes) of oil and gas wells and 3D printing technologies. • Experimental analysis of immersed buoyant viscoplastic injection in Newtonian fluid. • Observed flow regimes classified into breakup, coiling, and bulging. • Analysis of yielding, necking/pinch-off, and length of filaments for breakup regime. • Coiling subregimes categorized as regular, free, and irregular coiling. • Analysis of maximum penetration depth and subregimes in bulging regime.

Two-phase interfacial structure development in vertical narrow rectangular channels

This study has experimentally investigated flow characteristics of two group bubbles in upward two-phase flows in a vertical narrow rectangular channel with 0.993 mm in gap, 40 mm in width, 2000 mm in height, and 1.94 mm in equivalent hydraulic diameter, Dh. The local measurements are performed at seven axial positions (z/Dh =52, 104, 155, 207, 415, 622, 829 (z: the axial distance from the inlet) using a high-speed camera. The database of the locally evolving parameters has been established by processing the images from the high-speed camera measurements. The measured parameters include the void fraction, interfacial area concentration (IAC), Sauter mean diameter and number density of group-1 and -2 bubbles, and gas-phase velocity of all bubbles. A total of 14 flow conditions are set at four different superficial liquid velocities ranging from 0.214 m/s to 2.08 m/s and different superficial gas velocities ranging from 0.0755 m/s to 1.70 m/s at the inlet. The observed flow regimes cover the bubbly, cap-bubbly, and slug flows. The measured void fraction ranges from 3.92 % to 42.6 %. The axially developing features of the two-phase flows are analyzed for the three flow regimes. Abrupt and gradual axial two-group bubble evolutions with intensive bubble coalescence at the flow regime transition are, respectively, observed at low and high superficial liquid velocity conditions. The newly-obtained experimental database has been used to evaluate the existing two-group interfacial area transport equation (IATE) and its corresponding source and sink models for the two-phase flow in the vertical narrow rectangular channel. Group-1 bubble IAC mean relative error of 21.1% and group-2 bubble IAC mean relative error of 33.4% have been obtained in the evaluations. The existing two-group IATE cannot satisfactorily predict the intensive bubble coalescence and the intragroup transport of the two-group bubbles at the transition from bubbly to slug flow in the vertical narrow rectangular channel. Therefore, it is necessary to improve the existing models of the intergroup and intragroup bubble interactions in the existing two-group IATE in the future.

Flow regimes of a single pulse of inelastic and elastic liquids from a round capillary tube

The ejection of liquids through round nozzles is a commonplace process in many industrial applications, from inkjet printing to bottling of consumer products. In this work, a Computational Fluid Dynamics model of the ejection of inelastic and elastic liquids through a round capillary tube has been developed to assess the influence of the ejection’s duration and velocity on the regimes of jet/droplet formation. Simulations have been performed at different Weissenberg and Ohnesorge numbers to further assess the impact of the fluid’s physical properties on the observed flow regimes. Several regimes have been identified: no fluid detachment, single droplet formation, and breakup into several droplets. The presence of elasticity has been observed to delay the breakup of droplets from the nozzle. More importantly, the results show that the injection time has an impact on the dynamics of droplet formation, having a crucial role on the process design of various industrial applications.

Visualization of two-phase refrigerant flow in the inlet header of brazed plate heat exchangers and its effect on distribution

• Two-phase flow visualization is achieved by a clear window on the inlet header. • Flow regime in the inlet header is periodic and one cycle has two or three stages. • Flow regime in the inlet header significantly affects the two-phase distribution. • Effects of mass flux, inlet vapor quality, and the number of plates are examined. This paper presents an experimental study of two-phase R134a flow in the inlet header of brazed plate heat exchangers and its effect on flow distribution among the channels. Visualization of the two-phase flow is accomplished through a 3-D printed transparent window on the inlet header of the heat exchangers. The two-phase flow distribution among channels is quantified based on infrared images of the heat exchanger sidewalls. At the test conditions, the observed flow regimes in the inlet header are periodic and two or three stages are identified in one cycle: top corner vapor flow, vapor jet flow, and (conditional) liquid blockage flow. Among them, the top corner vapor flow affects the distribution most, in which the vapor refrigerant is mainly present at the top corner of the header and branches out through the first several channels, leaving the liquid refrigerant to occupy the rest flow area of the inlet header and present a single-phase like distribution profile. When the inlet vapor quality increases, the distribution of the liquid refrigerant is improved since the vapor refrigerant can reach more downstream channels to help balance the total pressure drop. With the mass flux increases, the maldistribution caused by the header induced pressure drop is more significant, which compromises the benefit brought by the higher vapor momentum. When the number of plates is increased, the liquid refrigerant distribution is worse due to an increased pressure drop in the headers.

Dimensionless analysis on liquid–liquid two-phase flow patterns in a numbered-up microfluidic device

Flow patterns of six liquid–liquid systems in a numbered-up microfluidic set-up were studied in this work. Chloroform-water, butyl acetate-water, ethyl acetate-water, kerosene-water, butanol-water and octanol–water were chosen as test liquids. Three distinct flow regimes were observed in the parallelized microfluidic device: slug flow, droplet flow and parallel flow. A uniform flow distribution was achieved in the scaled-out microfluidic device for all observed flow regimes. Flow non-uniformity was determined based on both the volumetric flow rate and slug size/droplet size/interface position for each microchannel. The two-phase interface's position relative to the microchannel walls was considered a criterion for flow non-uniformity measurement in parallel flow. A comprehensive dimensionless analysis was also performed to determine which dimensionless numbers are appropriate for presenting universal flow maps. Re-0.31We0.41, We0.07Ca0.31, Re0.07Ca0.41, Ca0.5Oh-0.14, We0.25Oh0.31 and Re0.5Oh0.82 were identified as the suitable combinations of dimensionless numbers for proposing generalized flow pattern maps for the numbered-up set-up. For the slug and droplet flow regimes, slug and droplet length and velocity were also investigated.

Lattice Boltzmann analysis of fluid structure interaction mechanism around a row of five side-by-side square cylinders

In this paper numerical investigations are performed to examine the effect of Reynolds numbers (Re) and spacing ratios (g) on flow around a row of five side-by-side square cylinders using the lattice Boltzmann method. The Reynolds number is varied in the range 75 ≤ Re ≤ 175, while spacing ratio is varied between 0.5 and 5. The flow structure mechanism around a row of five side-by-side square cylinders is studied in terms of vorticity contours visualization, time trace analysis of drag and lifts coefficients, and power spectrum analysis of lift coefficient. The effect of Re on force statistics like mean drag coefficient and Strouhal number is also analyzed. The present data are compared with the data of single square cylinder and good agreement is observed for large spacing ratio (g = 5). The flow behind five side-by-side square cylinders is classified into three different flow regimes and these regimes are further subdivided into seven different regimes. The observed flow regimes are compared with those of the other researchers published studies and found good agreement.

Flow of Non-Newtonian Fluids in a Single-Cavity Microchannel.

Having a basic understanding of non-Newtonian fluid flow through porous media, which usually consist of series of expansions and contractions, is of importance for enhanced oil recovery, groundwater remediation, microfluidic particle manipulation, etc. The flow in contraction and/or expansion microchannel is unbounded in the primary direction and has been widely studied before. In contrast, there has been very little work on the understanding of such flow in an expansion–contraction microchannel with a confined cavity. We investigate the flow of five types of non-Newtonian fluids with distinct rheological properties and water through a planar single-cavity microchannel. All fluids are tested in a similarly wide range of flow rates, from which the observed flow regimes and vortex development are summarized in the same dimensionless parameter spaces for a unified understanding of the effects of fluid inertia, shear thinning, and elasticity as well as confinement. Our results indicate that fluid inertia is responsible for developing vortices in the expansion flow, which is trivially affected by the confinement. Fluid shear thinning causes flow separations on the contraction walls, and the interplay between the effects of shear thinning and inertia is dictated by the confinement. Fluid elasticity introduces instability and asymmetry to the contraction flow of polymers with long chains while suppressing the fluid inertia-induced expansion flow vortices. However, the formation and fluctuation of such elasto-inertial fluid vortices exhibit strong digressions from the unconfined flow pattern in a contraction–expansion microchannel of similar dimensions.

Flow regime and void fraction predictions in vertical rod bundle flow channels

This paper has studied the flow regimes and their transitions in upward gas-liquid two-phase flows in vertical rod bundle flow channels. The past experimental observations on the flow regimes have been extensively reviewed and analyzed. Various flow regimes with the observer-dependent names are re-classified into 5 flow regimes, namely, bubbly, finely dispersed bubbly, cap-bubbly, churn and annular flows according to their different flow characteristics in the vertical rod bundle flow channels. In view of the problems in the available flow regime transition criteria and the drift-flux correlations, this paper has proposed the mechanisms for the bubbly to cap-bubbly flow transition, the cap-bubbly to churn flow transition, the transition to annular flow and the transition to the finely dispersed bubbly flow and developed the corresponding flow regime transition criteria to predict the five flow regimes based on these mechanisms. This paper has further improved Han et al. correlations for the drift-flux parameters of the distribution parameter and the drift velocity to predict the void fractions in the 5 flow regimes, together the newly-developed transition criteria, in the vertical rod bundle flow channels. The newly-developed flow regime transition criteria and the improved Han et al. correlation for the drift-flux parameters of the distribution parameter and the drift velocity have been examined with the experimental data. The examination has concluded that the newly-developed flow regime transition criteria can correctly predict 82.9% of the 451 observed flow regime data in the vertical rod bundle flow channels and the drift-flux model using the improved Han et al. correlation and the newly-developed flow regime transition criteria can give satisfactory prediction for the 959 experimental data of the void fraction with the mean relative error of 0.0766.

Development of a Real-Time Objective Gas-Liquid Flow Regime Identifier Using Kernel Methods.

Currently, flow regime identification for closed channels has mainly consisted of direct subjective methods. This presents a challenge when dealing with opaque test sections of the pipe or at gas-liquid flow rates where unclear regime transitions occur. In this paper, we develop a novel real-time objective flow regime identification tool using conductance data and kernel methods. Our experiments involve a flush-mounted conductance probe that collects voltage signals across a closed channel. The channel geometry is a horizontal annulus, which is commonly found in many industries. Eight distinct flow regimes were observed at selected gas-liquid flow rate settings. An objective flow regime identifier was then trained by learning a mapping between the probability density function (PDF) of the voltage signals and the observed flow regimes via kernel principal components analysis and multiclass support vector machine. The objective identifier was then applied in realtime by processing a moving time-window of voltage signals. Our approach has: 1) achieved more than 90% accuracy against visual observations by an expert for static test data; 2) successfully visualized conductance data in 2-D space using virtual flow regime maps, which are useful for tracking flow regime transitions; and 3) introduced an efficient real-time automatic flow regime identifier, with only conductance data as inputs.