Varying Flow Velocities Research Articles

Calcium Carbonate Deposition Model Supporting Multiple Operating Conditions Based on the Phase-Field Method for Free-Surface Flows

The drainage systems of tunnels situated in limestone regions frequently encounter crystallization blockages. Numerous studies have addressed this issue, and their findings identified factors such as the flow velocity and temperature as influencing the crystallization process. However, these studies could not predict the occurrence of crystallization. Regarding theoretical approaches, most studies have focused on full-pipe operations or have solely considered flow-field dynamics without including simulations of the chemical reactions and mass transfers. This study introduces a mass-transfer model for drainage pipes based on a two-phase flow (water and air) with a free surface and non-full pipe flow that simulates the crystallization deposition process in drainage pipes. This model can predict the deposition conditions at varying flow velocities and intuitively visualize the crystallization process under the influence of various factors. The impact of flow velocity on the overall crystallization deposition process can be directly analyzed through simulations developed using this model. The results show that under conditions of incomplete pipe flow with no pressure at the outlet, the weight of the deposition first increases and then decreases within a certain velocity. This model can depict the variations within a 30 d period.

Investigation of the immersion cooling system for 280Ah LiFePO4 batteries: Effects of flow layouts and fluid types

The widespread use of high-capacity LiFePO4 batteries (LFPB) is crucial for meeting the growing demand for energy storage systems (ESSs). This requires effective thermal management systems, and single-phase immersion cooling (SPIC) is emerging as a promising option due to its superior cooling capability. This paper investigates the effects of flow layout and fluid type on 280 Ah LFPB under SPIC through experimental and numerical analyses. Three flow layouts (opposite sides, same side, and jet impingement) are proposed, and six fluids are used for simulations. Results show that the jet impingement achieves the lowest temperature and pressure drop. During 1P discharge with DF1 flowing at 0.006 m/s, the maximum temperature, temperature difference, and pressure drop are 317.67 °C, 4.71 °C, and 0.09 Pa, respectively. Varying flow velocities within 0.006–0.053 m/s significantly impact battery temperature in the same-side layout. The volatility due to different fluid types, including CV,ΔP (pressure drop), CV,Tmax (maximum temperature) and CV,ΔT (temperature difference) are presented. As the flow velocity increases, CV,ΔP decrease by 35.9 %, 39.4 %, and 36.2 % for opposite sides, jet impingement, and same side, respectively. CV,Tmax increases with the P-rate, and the same-side layout has the lowest CV,Tmax, below 0.9 % at 0.5P and 0.6 % at 1P. This study emphasizes that the effect of fluid type should be considered in the design of flow layouts, especially at low flow rates. Experimental observation indicates that no ignition or explosion occurred during battery thermal runaway under SPIC. The maximum battery temperature during thermal runaway is 241.9 °C. This research provides valuable insights into SPIC application and fluid selection for ESS.

A feature sample screening and local outlier factor fusion method for detecting tidal stream turbine blade impact fault

The impact fault caused by ocean creatures poses a risk to the safe operation of tidal stream turbine blades. However, it is difficult to detect the weak impact fault directly because the collected signal is disturbed by the waves, turbulence, and continuously variable flow velocity. To solve this problem, a fusion method of feature sample screening and local outlier factor is proposed in this paper. This method consists of three main parts. First, the Teager–Kaiser energy operator and the sliding window technique are introduced to extract the envelope statistical features from the current signal. Second, a parameter optimized density-based spatial clustering of applications with noise (DBSCAN) algorithm is proposed to perform feature sample screening before detecting. Notably, the conventional DBSCAN algorithm is sensitive to the parameter selection and lacks the capability of adaptive screening, so this paper proposes an adaptive sand cat swarm optimization algorithm to optimize the parameters. Finally, the local outlier factor is utilized to detect faults based on the screened feature samples. The experimental results show that the proposed method stands out in reducing the false alarm rate compared with traditional methods. Specifically, within the flow velocity ranges of 1.0–1.3 m/s and 1.3–1.6 m/s, the false alarm rates can reach 0% and 0.17%, respectively.

Structures of Laminar Lean Premixed H2/CH4/Air Polyhedral Flames: Effects of Flow Velocity, H2 Content and Equivalence Ratio

AbstractPolyhedral Bunsen flames, induced by hydrodynamic and thermo-diffusive instabilities, are characterized by periodic trough and cusp cellular structures along the conical flame front. In this study, the effects of flow velocity, hydrogen content, and equivalence ratio on the internal cellular structure of premixed fuel-lean hydrogen/methane/air polyhedral flames are experimentally investigated. A high-spatial-resolution one-dimensional Raman/Rayleigh scattering system is employed to measure the internal scalar structures of polyhedral flames in troughs and cusps. Planar laser-induced fluorescence of hydroxyl radicals and chemiluminescence imaging measurements are used to quantify the flame front morphology. In the experiments, stationary polyhedral flames with varying flow velocities from 1.65 to 2.50 m/s, hydrogen contents from 50 to 83%, and equivalence ratios from 0.53 to 0.64 are selected and measured. The results indicate that the positively curved troughs exhibit significantly higher hydrogen mole fractions and local equivalence ratios compared to the negatively curved cusps, due to the respective focusing/defocusing effect of trough/cusp structure on highly diffusive hydrogen. The hydrogen mole fraction and local equivalence ratio differences between troughs and cusps are first increased and then decreased with increasing measurement height from 5 to 13 mm, due to the three-dimensional effect of the flame front. With increasing flow velocity from 1.65 to 2.50 m/s, the hydrogen mole fraction and local equivalence ratio differences between troughs and cusps decrease, which is attributed to the overall decreasing curvatures in troughs and cusps due to the decreased residence time and increased velocity-induced strain. With increasing hydrogen content from 50 to 83%, the hydrogen mole fraction and local equivalence ratio differences between troughs and cusps are amplified, due to the enhanced effects of the flame front curvature and the differential diffusion of hydrogen. With increasing equivalence ratio from 0.53 to 0.64, a clear increasing trend in hydrogen mole fraction and equivalence ratio differences between troughs and cusps is observed at constant flow velocity condition, which is a trade-off result between increasing effective Lewis number and increasing curvatures in troughs and cusps.

Scour depth dynamics in varied spacing spur dike configurations: A comprehensive analysis

Spur dikes, vital for enhancing river ecosystem biodiversity, also contribute to the creation of intricate flow patterns and scour phenomena. In the context of existing research, which predominantly concentrates on single spur dikes, this study stands out by specifically delving into the temporal changes in scour depth near initial spur dike in multiple spur dikes. Varied spacings, lengths and flow velocities are considered in this exploration. After comprehensive literature analysis, it could be asserted that use of multiple spur dikes consistently results in shallower equilibrium scour depths compared to a single spur dike. The study introduces a predictive model by examining the impact of different influencing factors, including spacing, length, and flow velocity, on scour depth.The proposed equation establishes a robust correlation between the observed and estimated scour depth values. The study explores the temporal changes in scour depth, revealing that the time needed to arrive at equilibrium scour depth is drastically reduced when employing multiple spur dikes. Furthermore, the investigation highlights that in multiple spurs in series, the maximum equilibrium scour is lower compared to that in single spur dikes. The model, encompassing various parameters such as flow velocity, spacing, length, and time, demonstrates high predictive accuracy. Overall, this study provides valuable insights into the dynamic behaviour of scour at multiple spur dikes and offers a predictive tool for effective riverbank protection and ecosystem management. In doing so it contributes to the overarching aim of achieving Sustainable Development Goals (SDGs) in river management ecosystem preservation.

A time-dependent ice accretion model for trap-setting fishing vessels with filigree structures

This paper describes a time-dependent methodology for calculating the rate of ice accretion on vessels with filigree structures. It combines Newton’s Second Law for spray droplet trajectories with time varying flow velocities determined using computational fluid dynamics (CFD). The mass flux of ice is determined by solving a set of partial differential equations describing the conservation of mass, heat, and salt in the boundary layer of brine near the ice surface. Icing predictions numerically generated by this approach areevaluated against current stability regulations for fishing vessels.

Individual and combined impacts of carbon dioxide enrichment, heatwaves, flow velocity variability, and fine sediment deposition on stream invertebrate communities.

Climate change and land-use change are widely altering freshwater ecosystem functioning and there is an urgent need to understand how these broad stressor categories may interact in future. While much research has focused on mean temperature increases, climate change also involves increasing variability of both water temperature and flow regimes and increasing concentrations of atmospheric CO2, all with potential to alter stream invertebrate communities. Deposited fine sediment is a pervasive land-use stressor with widespread impacts on stream invertebrates. Sedimentation may be managed at the catchment scale; thus, uncovering interactions with these three key climate stressors may assist mitigation of future threats. This is the first experiment to investigate the individual and combined effects of enriched CO2, heatwaves, flow velocity variability, and fine sediment on realistic stream invertebrate communities. Using 128 mesocosms simulating small stony-bottomed streams in a 7-week experiment, we manipulated dissolved CO2 (ambient; enriched), fine sediment (no sediment; 300 g dry sediment), temperature (ambient; two 7-day heatwaves), and flow velocity (constant; variable). All treatments changed community composition. CO2 enrichment reduced abundances of Orthocladiinae and Chironominae and increased Copepoda abundance. Variable flow velocity had only positive effects on invertebrate abundances (7 of 13 common taxa and total abundance), in contrast to previous experiments showing negative impacts of reduced velocity. CO2 was implicated in most stressor interactions found, with CO2 × sediment interactions being most common. Communities forming under enriched CO2 conditions in sediment-impacted mesocosms had ~20% fewer total invertebrates than those with either treatment alone. Copepoda abundances doubled in CO2-enriched mesocosms without sediment, whereas no CO2 effect occurred in mesocosms with sediment. Our findings provide new insights into potential future impacts of climate change and land use in running freshwaters, in particular highlighting the potential for elevated CO2 to interact with fine sediment deposition in unpredictable ways.

A Review and Design Principle of Fixed-Bottom Foundation Scour Protection Schemes for Offshore Wind Energy

Foundation scour is the erosion of sediments around pile foundations by wave and current in offshore wind energy. This phenomenon destabilizes foundations and poses a threat to pile safety. Therefore, scour protection becomes a crucial challenge in offshore wind projects. This paper reviews and synthesizes recent publications and patented technologies related to scour protection. Considering the primary engineering concerns, the paper proposes design principles for effective scour protection schemes to standardize evaluation criteria. These principles prioritize efficacy, independence, and cost-efficiency, enabling the analysis of scour protection scheme applicability. In addition, this paper summarizes and describes common protection schemes in the literature. The effectiveness of their protection is analyzed and summarized, and their economic and performance independence is evaluated. This paper categorizes flow-altering scour protection schemes found in the literature. Based on a comprehensive understanding of the mechanisms and engineering requirements of scour protection, the paper proposes a focus on determining the erosion reduction rate curve (Ep−U/Uc curve) as a key criterion for evaluating the effectiveness of protection schemes under varying flow velocities and the erosion reduction rate of scour protection schemes under extreme conditions. The study highlights the necessity of establishing a comprehensive design evaluation methodology, which is crucial for addressing the significant challenges related to scour encountered in offshore wind power projects.

Performance of exhaust gas-natural gas reforming under simulated exhaust conditions from marine NG engine: An experimental and thermodynamic study

Stable and efficient hydrogen production through exhaust gas-natural gas reforming is crucial for the implementation of reformed exhaust gas-fuel recirculation (REGR) technology in marine LNG engines. The reforming reaction is controlled by the physicochemical characteristics of the catalyst and the initial conditions. Ni-based catalysts have been extensively studied for methane reforming at medium-high temperatures. However, there is limited research on the complex multiphase reforming process using Ni-based catalysts at low temperatures, variable gas flow velocity, multi-component, and high dilution exhaust conditions. Therefore, this study aimed to examine and evaluate the reforming characteristics of modified La–Ni/Ca–Al catalysts, as well as the differences in catalytic physicochemical properties before and after the reforming reaction under the simulated exhaust gas conditions. Characterization results of the catalyst samples demonstrated that the modified catalyst exhibited ideal activity in the low-temperature reforming process, along with good resistance to thermal sintering and carbon deposition. The relative content of CH4 to O2 (M/O ratio) and the temperature of feedstock were identified as critical parameters controlling the reforming reactions. To achieve efficient hydrogen production, the optimum M/O ratio should be within 1.5–2.5, which could guide the efficient operation of our developed reformer. The study determined the critical feedstock temperatures for methane oxidation, steam reforming, and dry reforming reactions activated in the reforming system to be approximately 300 °C, 400 °C, and 500 °C, respectively. These findings highlighted the promising potential of exhaust gas-natural gas reforming as a means to recover and utilize O2, H2O, CO2, and heat from the exhaust gas. The insights gained from this present investigation provide valuable guidance for the development of the REGR system.

Impacts of Channel‐Spanning Log Jams on Hyporheic Flow

AbstractIn‐stream wood structures, such as single logs, river steps, and debris dams, are known to drive hyporheic flow, defined as the flow that goes into the subsurface region and then back to the free‐flowing surface water. The hyporheic flow plays an important role in regulating water quality and biogeochemical cycles in rivers. Here, we investigated the impact of a channel‐spanning porous log jam, representing piles of wood logs, on hyporheic flow through a combination of direct visualization and theories. Specifically, we developed a method using refractive index‐matched sediment to directly visualize the hyporheic flow around and below a porous log jam, formed by piles of cylindrical rods, in a laboratory flume. We tracked the velocity of a fluorescent dye moving through the transparent sediment underneath the log jam. In addition, we measured the water surface profile and the spatially varying flow velocity near the log jam. Our results show that the normalized log jam‐induced hyporheic flux remained smaller than 10% at Froude numbers () below 0.06 and increased by a factor of five with increasing at . We combined the mass and momentum conservation equations of surface flow with Darcy's equation to explain the dependency of the log jam‐induced hyporheic flux on . Further, we observed that at , the water surface dropped noticeably and the turbulent kinetic energy increased immediately on the downstream side of the log jam. These findings will facilitate future quantification of hyporheic flow caused by channel‐spanning porous log jams.

Soil colloids can significantly enhance spreading of polybromodiphenyl ethers in groundwater by serving as an effective carrier

Polybromodiphenyl ethers (PBDEs), the widely used flame retardants, are common contaminants in surface soils at e-waste recycling sites. The association of PBDEs with soil colloids has been observed, indicating the potential risk to groundwater due to colloid-facilitated transport. However, the extent to which soil colloids may enhance the spreading of PBDEs in groundwater is largely unknown. Herein, we report the co-transport of decabromodiphenyl ester (BDE-209) and soil colloids in saturated porous media. The colloids released from a soil sample collected at an e-waste recycling site in Tianjin, China, contain high concentration of PBDEs, with BDE-209 being the most abundant conger (320 ± 30 mg/kg). The colloids exhibit relatively high mobility in saturated sand columns, under conditions commonly observed in groundwater environments. Notably, under all the tested conditions (i.e., varying flow velocity, pH, ionic species and ionic strength), the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids, even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions involved. Additionally, the mass of BDE-209 retained in the columns also correlates strongly with the mass of retained colloids. Apparently, the PBDEs remain bound to soil colloids during transport in porous media. Findings in this study indicate that soil colloids may significantly promote the transport of PBDEs in groundwater by serving as an effective carrier. This might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.

Coupled CFD-DEM simulation and experimental study of particle distribution and accumulation during tailings seepage process

The movement of tailings particles in waste rock systems under different flow rates was studied using experimental and numerical methods, aiming to provide theoretical guidance for preventing particle infiltration. The research results established a calculation relationship between pressure drop, porosity, and waste rock thickness. They also revealed the self-similarity of blockage accumulation within the waste rock. The overall study indicates that smaller particles can pass through the waste rock, but larger particles face greater difficulties. It becomes highly challenging for particles to pass through when they exceed the pore spaces between the largest waste rock particles. The distribution pattern of blockage decreases gradually from the upper part to the lower part of the waste rock pile, with proportions of blockages at different depths being 35.2%, 22.7%, 15.5%, 15%, and 11.6%. The study also examined the cumulative distribution of tailings particles passing through the waste rock under varying flow velocities (0.2 m/s, 0.3 m/s), showing that the quantity of tailings particles passing through the waste rock at 0.3 m/s is approximately 1.15 times that at 0.2 m/s. Additionally, the effectiveness of using geotextile for sealing was investigated, providing theoretical support for determining the application of waste rock particle size, thickness, and geotextile in sealing tailings particles. Moreover, understanding the self-similarity and velocity variation patterns of particles helps in selecting suitable waste rock characteristics.

Theoretical and simulation analysis of the measurement of polarized fluid flow in a circular pipe with electric field excitation

Measurement of conductive fluid flow velocity is essential in applications such as measuring the velocity of water flow in the agriculture sector, sewage water treatment plants, and metal refining industries. This paper proposes a contactless flow measurement device for computing the flow velocity of conductive fluids based on movement of polarized fluid flow. The proposed simulation model of the flow meter can also determine the conductivity of the fluid for varying flow velocity. The obtained simulated results concur with the earlier theoretical studies. Based on the interpretations in the underlying assumptions and physics of a fluid flow under a source of an electric field, it reveals that it is possible to measure a flow velocity of 0.01–10 m s−1 for conductive fluids of 0.1–10 S m−1.

Estimation of energy consumption and transportation characteristics for slurry flow through a horizontal straight pipe using computational fluid dynamics

The energy expense of slurry transportation through the pipeline plays a vital role in the economics of various modern industries, such as mining, crude oil, petroleum, and mineral processing. Therefore, it is essential to develop a suitable condition by which we can efficiently transport slurry without affecting the environment and capital costs. To solve these problems, a steady state three-dimensional multiphase Eulerian RNG k–ε turbulence model based on the kinetic theory of granular flow is developed to investigate transportation parameters like pressure distribution, concentration distribution, head loss, settling velocity, and specific energy consumption. Four different particles named bottom ash, glass beads, iron ore, and silica sand with five different sizes, 125, 200, 275, 350, and 440 μm are transported through 3.8 m long straight pipe having 54 mm pipe diameter. The trends of various transportation properties with varying flow velocity (Vm = 1–5 m/s) and efflux concentration (Cw = 40%–60%) are presented. The numerically obtained results for different slurries and water are in good agreement with the past experimental data available in the literature. The computational finding shows that the transportation of bottom ash requires minimum energy, whereas silica sand needs the maximum. In addition, the degree of deviation into transportation properties increases with the particle size, efflux concentration, and flow velocity.

Analysis of Flow-Induced Vibrations in a Heat Exchanger Tube Bundle Subjected to Variable Tube Flow Velocity

Analysis of Flow-Induced Vibrations in a Heat Exchanger Tube Bundle Subjected to Variable Tube Flow Velocity

DETERMINATION OF WALL HEAT FLUX BASED ON BUBBLE DEPARTURE AND LIFT-OFF DIAMETERS FOR VARYING PRESSURE AND FLOW VELOCITY CONDITIONS

In this study, the bubble departure and lift-off (BDL) boiling model has been improved by implementing the subcooling suppression factor and flow-related parameters, with the aim of developing an accurate heat transfer model for various engineering applications. The BDL model has been exploited using a MATLAB program to determine the variation of wall heat flux that controls the boiling curve. Three different parameters, namely, bulk flow velocity, operating pressure, and bulk flow temperature have been considered in this study. Experimental conditions were simulated as per Chen's BDL model algorithm, and the resulting wall heat flux was compared with the measured values. Additionally, different boiling curves for bubble departure and lift diameters were generated and their effect on varying operating conditions was studied. The resultant boiling curves were compared with the experimental data by means of mean absolute error (MAE) and regression coefficient (<i>R</i><sup>2</sup>) values. In general, with a reasonable margin of error, i.e., MAE = 3.35%, and <i>R</i><sup>2</sup> = 0.99, the algorithm performed well in comparison with the experimental data. The bubble departure and lift diameters were also correlated with the experiment and the predictions were satisfactorily close.

Multifunctional rotational active valve for flow control in paper-based microfluidic devices

In paper-based microfluidics, the development of a robust and multi-role valve mechanism is important for flow control to perform multistep biochemical assays. The previous valve designs were complex, limited in their operational capabilities to simply ON/OFF functionality, required complex circuitry and auxiliary devices for valve actuation, or were unfit for friendly user operation. Herein, we present a multifunctional, simple, robust and cost effective rotational active valve (RAV) for paper-based microfluidics devices. In addition to ON/OFF, it achieves variable flow velocity by varying the contact area of RAV channel, by varying the RAV channel length, or by changing the RAV channel width. The functionality was demonstrated in paper-based microfluidic devices for sequential delivery with intermixing, multi-reagent valve regulation with washing step, and fluid distribution to multiple delivery zones. Finally, we conducted a multistep biochemical assay for the detection of total protein, uric acid and albumin protein in human serum at various concentration (dilution ranges from 40% to 100%) using RAV. We believe that our RAV can solve complex biochemical assays in paper-based devices with potential to be commercialized due to its cost-effectiveness, easy fabrication and robust nature of flow control enabling to achieve a viable point-of-care diagnostic platform.

Attachment of Extracellular Metabolic Products of Lysinibacillus sp . DRG3 on Sand Surface under Variable Flow Velocities and Bioprocesses

The efficacy of microbially mediated stabilization of soil mass depends on soil aggregation and further depends on the complex interplay of environmental parameters, microbial extracellular metabolic products, and surface characteristics of soil particles. Failures of flood control dikes or similar structures often culminate from minor erosion of soil particles initiated by groundwater seepage. Although the introduction of microbial metabolic products in controlling soil erosion has been studied by researchers, the influence of slow fluvial activities on the composition, characteristics, and their impacts on attachment mechanisms of extracellular polymeric substances (EPS) on soil surfaces have remained unexplored. Impacts of slow fluvial activities on the amount and chemical composition of EPS produced by Lysinibacillus sp. DRG3, a nonpathogenic soil bacterium, and the attachment mechanisms of the EPS produced under noncalcifying, nonureolytic, and ureolytic calcifying bioprocesses on the sand surfaces were investigated. DRG3-inoculated specimens were incubated in the presence of steady circulation of aqueous media containing minimal concentrations of minerals and carbon and nitrogen sources to simulate groundwater movements through soil. Quantity, compactness, continuity, and viscosity of EPS and the amounts of carbohydrate, protein, lipid, DNA, and RNA found in EPS increased with circulation velocity and incubation duration. EPS were found to attach to sand through electrostatic interaction and hydrogen bonding. Internally, EPS components interacted with each other through electrostatic interaction, hydrogen bonding, and hydrophobic interaction. Electrostatic interaction appeared to weaken with increasing media circulation intensity and alkalinity. In contrast, EPS production and hydrogen bonding intensified under increased media circulation. Results of this investigation suggest microbe-mediated soil aggregation becomes stronger and more efficient under slow media circulation and are expected to have implications on microbially mediated soil stabilization, particularly in addressing soil erosion. This study provides useful insights for successful field implementation of biomediated soil stabilization. Work presented herein also demonstrates a role for microbial activities found in subterranean environments in strengthening an existing sand deposit.

Dispersion of motile bacteria in a porous medium

Understanding flow and transport of bacteria in porous media is crucial to technologies such as bioremediation, biomineralization and enhanced oil recovery. While physicochemical bacteria filtration is well documented, recent studies showed that bacterial motility plays a key role in the transport process. Flow and transport experiments performed in microfluidic chips containing randomly placed obstacles confirmed that the distributions of non-motile bacteria stays compact, whereas for the motile strains, the distributions are characterized by both significant retention as well as fast downstream motion. For motile bacteria, the detailed microscopic study of individual bacteria trajectories reveals two salient features: (i) the emergence of an active retention process triggered by motility, (ii) enhancement of dispersion due to the exchange between fast flow channels and low flow regions in the vicinity of the solid grains. We propose a physical model based on a continuous time random walk approach. This approach accounts for bacteria dispersion via variable pore-scale flow velocities through a Markov model for equidistant particle speeds. Motility of bacteria is modelled by a two-rate trapping process that accounts for the motion towards and active trapping at the obstacles. This approach captures the forward tails observed for the distribution of bacteria displacements, and quantifies an enhanced hydrodynamic dispersion effect that originates in the combined effect of pore-scale flow variability and bacterial motility. The model reproduces the experimental observations, and predicts bacteria dispersion and transport at the macroscale.

Development of a sampling probe with a small non-isokinetic sampling error in variable flow velocity environments

The flow velocity of exhaust gas from an industrial stack varies from facility to facility and can easily change over time, even in a stack. To accurately measure the concentration of fine particles such as PM10 or PM2.5 emitted in such environments, the conditions for isokinetic sampling must be satisfied. In this study, a novel sampling probe that generates a small error in particle concentration in variable flow velocity environments was developed, even though isokinetic sampling was not performed. The mass distributions obtained by isokinetic sampling using a conventional sampling probe at a flow velocity of 0–6 m/s were compared with those measured using the developed probe to verify the performance of the proposed probe. It was confirmed that the two mass distributions are similar within an error of 5% under all flow velocity conditions. The mass concentrations estimated through theoretical correction considering sampling loss or gain in non-isokinetic environments were also compared, and the distributions were quite similar within approximately 5%. This verifies that the proposed sampling probe can perform nearly perfect sampling of fine particles without changing the sampling flow rates, with minimal particle under- or overestimation caused by non-isokinetic sampling for variable flow velocity conditions.Copyright © 2022 American Association for Aerosol Research