Bubble Generation Research Articles

Hollow drop bubbles: A preliminary study of simplified prototype for improving copper(II) extraction with ACORGA® M5640 using coated bubble swarm

There are two well-defined processes for the types of copper ores. One for the processing of copper sulfides and another for the processing of the copper oxides. There are similarities between the two, particularly in the preparation stage of the run of mine (ROM) such as the crushing. However, significant differences exist in how to concentrate the elements of interest. Flotation is the most used concentration process to separate copper sulfide minerals from other minerals using air bubbles. For oxides, after the dissolution of copper, the solvent extraction (SX) process is the preferred path using two immiscible liquids to separate the copper.A line of investigation for solvent extraction is the use of a bubble coated with solvent to extract the metal of interest from the aqueous solution, some devices have been built and tested for this purpose using different principles to generate a coated bubble swarm. However, those equipments have been tested on laboratory and have not been scaled up to an industry level.The Hollow Drop (HD) concept was born from the idea of building a device to generate coated bubbles in a continuous swarm that could be scalable to an industry level. In this paper two columns were built and operated: a proof-of-concept column and a scale-up attempt for the extraction of Cu(II) fom an aqueous solution of 2.5 g L−1 using ACORGA® M5640 (25% v/v) in the Kerosene.The results show that we could generate a bubble swarm and conduct the solvent extraction process at a 97% recovery using our proposed coated bubble generator. However, in our scaled prototype test only a 70% recovery was achieved, which shows that our column is working but the scaling-up needs more investigation regarding the dimensions and flows of the process.

A redox homeostasis disruptor based on a biodegradable nanoplatform for ultrasound (US) imaging-guided high-performance ferroptosis therapy of tumors

ABSTRACT The synergistic disruption of intracellular redox homeostasis through the combination of ferroptosis/gas therapy shows promise in enhancing the antitumor efficacy. However, the development of an optimal delivery system encounters significant challenges, including effective storage, precise delivery, and controlled release of therapeutic gas. In this study, we propose the utilization of a redox homeostasis disruptor that is selectively activated by the tumor microenvironment (TME), in conjunction with our newly developed nanoplatforms (MC@HMOS@Au@RGD), for highly efficient ferroptosis therapy of tumors. The TME-triggered degradation of HMOS initiates the release of MC and AuNPs from the MC@HMOS@Au@RGD nanoplatform. The released MC subsequently reacts with endogenous hydrogen peroxide (H2O2) and H+ to enable the on-demand release of CO gas, leading to mitochondrial damage. Simultaneously, the released AuNPs exhibit GOx-like activity, catalyzing glucose to generate gluconic acid and H2O2. This process not only promotes the decomposition of MnCO to enhance CO production but also enhances the Fenton-like reaction between Mn2+ and H2O2, generating ROS through the modulation of the H+ and H2O2-enriched TME. Moreover, the generation of CO bubbles enables the monitoring of the ferroptosis treatment process through ultrasound (US) imaging. The efficacy of our prepared MC@HMOS@Au@RGD disruptors in ferroptosis therapy is validated through both in vitro and in vivo experiments.

Effect of electric field on bubble generation and dissolution characteristics in oil–paper insulation

AbstractThe interturn paper insulation of oil‐immersed power transformer windings, under the combined influence of electric fields, moisture, and conductor heating, will produce bubbles, which pose a significant threat to the insulation system. However, there is limited research on the characteristics of bubble evolution in oil–paper insulation under the influence of electric fields and the subsequent dissolution process. Based on the continuous observation of bubble size using electron microscopes, experimental and theoretical investigations into the formation and dissolution of bubbles under electric field conditions are presented. The effects of different field strengths on bubble evolution and dissolution characteristics were studied. The results showed that the electric field promoted both the generation and dissolution of bubbles, with a more pronounced effect observed at higher field strengths (below partial discharge (PD) inception electric field, hereafter referred to as PDIE). However, when the field strength exceeded PDIE, the bubbles tended to shrink and gradually increase in size. The changes in bubble volume were related to not only gas diffusion but also oxygen consumption and fault gases generation due to PD. A better understanding of the formation and dissolution characteristics of bubbles under varying field strengths is achieved. Furthermore, it also provides a reference for assessing the risk of bubble generation and conducting bubble‐related fault diagnosis during the overload operation of oil‐immersed power equipment.

Impact of bottom-blowing parameters on melt pool homogenization in a 120-ton converter based on carbon-oxygen reaction

This paper studies a 120 t converter, focusing on the influence of the CO bubbles generated by the carbon-oxygen reaction during the decarburization process on the stirring action of the melt pool. It examines the effect of the intensity and arrangement of bottom blowing on the homogenization effect, taking into account the dynamics of CO bubbles generated from the carbon-oxygen reaction. Initially, a macroscopic kinetics model for the generation of CO bubbles during the carbon-oxygen reaction in converter steelmaking is established. Subsequently, a water model simulation device for CO bubble generation from the converter's carbon–oxygen reaction is designed, establishing a 120 t converter water model experimental setup with a similarity ratio of 1:8. The main indicator for evaluating the homogenizing effect of the converter is the mixing time, based on which, experimental schemes are designed. Water model experiments are conducted to study the influence of bottom-blowing flow and nozzle arrangement on the melt pool's stirring flow field under the action of carbon-oxygen reaction. The results show that greater generation intensity of CO bubbles from the carbon-oxygen reaction leads to shorter mixing time in the melt pool; when the angular spread of the bottom-blowing elements is small, the bottom-blowing gas flow is relatively concentrated, facilitating stirring in the melt pool. However, increasing the angular spread of the nozzles to a certain extent leads to the dispersion of bottom-blowing energy, making it difficult to form effective stirring; when the bottom-blowing flow is less than 1.5 Nm3/h, the mixing time of the melt pool decreases with the increase of bottom-blowing flow; when the bottom-blowing flow is greater than 1.5 Nm3/h, the mixing time of the melt pool increases with the increase of bottom-blowing flow. In addition, a series of industrial experiments were carried out, and the research results were applied to the actual production process. By comparing the test results after the optimization scheme with the production data of the original process, it was found that the optimization scheme significantly improved the smelting efficiency and reduced the production cost. These research results not only provide a theoretical basis, but also provide practical guidance for the optimization of converter smelting process.

Rapid nucleation and growth of tetrafluoroethane hydrate enhanced by bubble and gas cycling

The application of hydrate technology is predominantly limited by the rapid nucleation and stable formation of hydrates, which could be promoted by the disturbance of bubbles. In this study, the effect of bubble generation and different bubble sizes on the nucleation and growth characteristics of R134a hydrates were investigated. The impact of three methods (depressurization-induced R134a vaporization, depressurization combined with stirring and gas cycling bubbling) of bubble effect and size on the nucleation, growth characteristics, and stability of R134a hydrate formation were explored. The research results indicate that utilizing only the depressurization method to induce R134a vaporization and bubble formation leads to a gas consumption rate of 19.6 mmol/min, which is 868 times higher than that in a pure water system. Furthermore, refining bubble size through stirring under depressurization conditions further augments the gas conversion rate by 8.6 %, and the optimal temperature for R134a hydrate formation is identified to be as low as 4 °C. Importantly, utilizing gas cycling as a means to generate bubbles enables uniform and rapid nucleation and growth of hydrates. Within a short 10 min, R134a hydrates was rapidly and stably formed, achieving a formation rate 35 times faster compared to the boiling-condensation method. In comparison to stirring-depressurization, the gas cycling method further increases the gas consumption rate by 10 %. The drawback of slow nucleation and growth rates in hydrates, as well as the need to enhance their stability, is addressed by the gas cycling method.

Visualized study and performance evaluation on a micro-grooved vapor chamber

The evaporation resistance and capillary flow both dominates the heat transfer performance of aluminum vapor chamber (VC) with micro-grooved wicks (MGW). This study presents the visualization experiments for three MGW VC samples with different cross-sectional shapes, including semicircular (MGW-S), V-shaped (MGW-V) and trapezoidal (MGW-T). The characterization of capillary rise dynamics is evaluated and compared by depicting the transient liquid front in vertical installation while the thermal spreading capability is examined horizontally at the quasi-steady state. Results show that the MGW-T exhibits the highest capillary pressure, and higher capillary rise rate can be obtained when applying acetone as working medium. As the groove shape impacting on the rate of bubble generation and detachment during evaporation process, the MGW-S obtains the lowest average thermal resistance. However, compared to the uniformly generated bubbles of acetone, it is revealed that ethanol might result in the slug or puddle at the evaporation area, which shortens the flow length of vapor and increases the average thermal resistance. When conducting under incremental heat loads, the boiling phenomenon of the working liquid becomes increasingly turbulent, and the average thermal resistance can be minimized from 2.6 K/W to the level lower than 1 K/W. As the result, when using acetone with filling ratio of 30%, the average thermal resistance of the MGW-T reaches 0.92 K/W under heat load of 60 W.

Significance of chemical reaction and viscous dissipation on magnetized-Marangoni convective flow of dusty Casson hybrid (AA7072+AA7075/sodium alginate) nanofluid with Soret and Dufour effects

ABSTRACT In the current study, mass and heat transfer flow of radiated Casson hybrid nanofluid with nanoparticles and dust deferment over sheet are explored. The Soret and Dufour effects, activation energy and microorganisms in the hybrid nanofluid model are described. Marangoni convection, a prominent occurrence in microgravity caused by surface tension gradients. It can be used for many different things, such as the creation of molten crystals, thin-film diffusion, the generation of vapour bubbles during nucleation, and semiconductor manufacturing. In sodium alginate, we wondered about the aluminium alloys AA7072 and AA7075. The aluminium alloys included in this study are specially made materials with improved heat transmission characteristics. aluminium and zinc are combined in AA7072 alloy in the ratios of 98 & 1, respectively, with the addition of silicon, ferrous metals, and copper. Similarly, AA7075 is a blend of aluminium, magnesium, zinc, and copper in the proportions of ~ 90, ~3, ~6, and ~ 1, respectively, with silicon ferrous and magnesium as additional metals. The controlling PDEs are transformed into nonlinear ODEs with the aid of a new set of similarity variables. These ODEs are then numerically solved using the RKF-45th method. The findings show that when the Marangoni convection parameter increases, the concentration, temperature, and microbiological characteristics drop while the velocity profile increases for both the dust and fluid phases.

Generate Comic Strips Using AI

The art of storytelling through comic strips has long been a favorite, grabbing the interest of readers of all ages and developing into a variety of genres today, from superhero comics to political comics. Comic strip readers are more literate, empathic, and open to social issues, according to studies. Comics have the power to change the way we see the world. This research paper presents a system (ComicGenie) for automatically creating comic strips for Batman based on user-entered text descriptions. The proposed system consists of distinct components such as character detection, environment detection, text bubble generation, and voiceover over the scenario, each specializing in different aspects of comic strip creation. SVM and fastText technologies in NLP were utilized for text classification when developing models. Overall, this research contributes to the field of comic strip creation, offering a comprehensive web application. The ComicGenie holds significant potential to revolutionize the comic industry and inspire new avenues for computer-generated storytelling.

The ablation behavior and modification mechanism of SiC under different laser energy

The laser modification pretreatment method is an effective way to address the machining difficulties of silicon carbide (SiC), a typical hard-to-machine material. Therefore, the ablation behavior and modification mechanism of SiC under different laser energy were explored in this paper. A new multi-scale model of laser irradiation SiC that couples heat transfer and fluid motion is first established. Then, a series of experiments is carried out to evaluate the model's accuracy, and the interaction between laser and SiC is discussed in detail. The results show that the dominant modification mechanism changes from coulomb explosion to multiphoton absorption, incubation effect, and heat accumulation with the laser energy increase. This leads the surface topography of SiC to transition from nanoparticle formation to disorder to a melting state. In ablative state, micro/nano porous and humps are formed at the edge of ablation groove due to surface tension, generation and rupture of bubbles, respectively. Furthermore, the surface roughness is not proportional to the laser energy due to the plasma shielding effect, and the surface roughness can be reduced by enhancing the flow of the molten material. Amorphous Si–O–C, Si and spherical SiO2 exist in deposition area, leading to SiC elastic modulus decreases from 347 GPa to 103.82 GPa, and the shear strength decreases from 20.9 GPa to 17.25 GPa. The results of this study can provide references for parameters selection and theoretical support for improving the machinability of SiC.

Air trap and removal on a pressure driven PDMS-based microfluidic device.

With the development of microfluidic technology, microfluidic chips have played a positive role in applications such as cell culture, microfluidic PCR, and nanopore gene sequencing. However, the presence of bubbles interferes with fluid flow and has a significant impact on experimental results. There are many reasons for the generation of bubbles in microfluidic chips, such as pressure changes inside the chip, air vibration inside the chip, and the open chip guiding air into the chip when driving fluid. This study designed and prepared a microfluidic device based on polydimethylsiloxane. First, air was actively introduced into the microfluidic chip, and bubbles were captured through the microfluidic device to simulate the presence of bubbles inside the chip in biological experiments. To remove bubbles trapped in the microfluidic chip, distilled water, distilled water containing surfactants, and mineral oil were pumped into the microfluidic chip. We compared and discussed the bubble removal efficiency under different driving fluids, driving pressures, and open/closed channel configurations. This study helps to understand the mechanism of bubble formation and removal in microfluidic devices, optimize chip structure design and experimental reagent selection, prevent or eliminate bubbles, and reduce the impact of bubbles on experiments.

Research on development and quantitative control preparation technology of array-type microfine bubbles generator

In traditional wastewater treatment, ozone injection efficiency is low. There is a need for the quantitative preparation of ozone-based microfine bubbles to balance bubble stability and ozone reactivity. To address this, we developed coaxial and T-type ozone-based microfine bubble generators and conducted experiments to compare their bubble production effects. The more effective generator was then compared with the traditional aeration method. The results indicate the following: 1. The coaxial type is more effective in producing ozone-based microfine bubbles. 2. The bubbles produced by the coaxial type have an average diameter of 0.2–0.4 mm and a residence time of ∼2 min, meeting microfine bubble standards. Experimental data analysis shows compliance with the force process and bubble growth mechanism under coaxial flow, meeting the requirements for quantitative and controllable ozone-based microfine bubble production. 3. Ozone bubbles from the coaxial method surpass those from traditional aeration in volume and concentration. More than 99.73% are microfine bubbles, with an ozone concentration of ∼84.5%. 4. The coaxial method more effectively reduces COD values in water, contributing to efficient wastewater treatment. This research presents new avenues for efficient sewage treatment.

Experimental study on modulation of homogeneous isotropic turbulence by bubbles of different sizes

The mechanism of turbulence modulation by bubbles is crucial for understanding and predicting turbulent bubbly flow. In this study, we conducted an experimental investigation of turbulence modulation by bubbles of different sizes in homogeneous isotropic turbulence using two-phase stereo-particle image velocimetry measurement techniques. Two bubble generation methods, electrolysis and porous medium, were employed to generate bubbles in micrometer and millimeter sizes, respectively. The oscillating grid system was utilized to generate homogeneous isotropic turbulence, allowing precise control of turbulent boundary conditions. The ratio of the fluctuating velocities and the comparison between turbulent kinetic energy and average kinetic energy indicated that the generated turbulence was nearly homogeneous and isotropic. With increasing turbulence intensity, micron-sized bubbles transition from suppressing turbulence to enhancing it, while millimeter-sized bubbles exhibit the opposite behavior. Turbulence modulation by millimeter-sized bubbles appears to be nearly isotropic, whereas micrometer-sized bubbles do not exhibit isotropy.

Liquid surface depression and bubble generation by acoustic radiation

AbstractLiquid surfaces can be depressed by applying acoustic radiation force. The balance between the acoustic radiation force, surface tension force, and buoyant force sustains the stable dimple depression. Beyond a certain threshold, higher acoustic radiation force leads to instability and bubble formation. The bubble size is determined by the acoustic radiation force and the liquid surface tension. Effective management of bubble generation can be achieved by controlling acoustic radiation waves. A novel method for creating depression on liquid surfaces and generating bubbles is described, which requires neither gas supply nor direct contact with equipment.

The temperature effect on the formation and growth of helium-vacancy clusters in bcc iron: A comprehensive molecular dynamics simulation

Bubble generation can significantly degrade the performance of fusion reactor structural materials. In this work, the temperature effects on the initial clustering of helium (He) atoms, the formation of helium-vacancy clusters (HenVm) and the subsequent growth of the clusters into bubbles in bcc iron under different conditions were simulated by molecular dynamics. The results show that He behaviors are primarily dominated by coalescence at temperature range from 400 K to 500 K, which leads to a preference for He to bind together. Conversely, when temperature is higher than 500 K, dissociation become more prominent, causing large He clusters to be hard to form. Under the conditions of increasing He concentration and irradiation dose, the higher the temperature, the higher the density of HenVm clusters at He concentration around 100 appm. However, the temperature dependence reversed at high He concentration. The detailed analysis of formation cases revealed the percentage of nucleation sites for He bubbles at defects during He segregation. In addition, there is no significant difference among the He/V ratio of HenVm clusters formed at vacancies, interstitial dislocation loops (IDLs) and interstitial sites during the cluster growth. However, the He/V ratio of He bubbles growing on edge dislocation (ED) is overall lower than those growing at other formation sites, since the growth of HenVm clusters on ED requires a lower pressure to kick out self-interstitial atoms (SIAs) or SIA clusters. The average He/V ratio of He bubbles in bulk decreases as temperature rises from 400 K to 800 K, while that of He bubbles growing on ED is independent of temperature.

Mass transfer enhancement and flow field simulations for a Venturi bubble generator with multiple inlet tubes

The Venturi device plays a crucial role in the Filtered Containment Venting System (FCVS), effectively preventing the release of radioactive pollutants from nuclear reactor containment during overpressure events. Various configurations of the Venturi device yield different outcomes, with mass transfer efficiency being contingent on bubble size and overall gas holdup. This study examines the impact of varying numbers of inlet tubes on the Venturi device, while keeping the inlet area constant. Specifically looking at the gas–liquid flow field, bubble behavior, and mass transfer capacity in the diverging section. By comparing Single Inlet Tube Venturi Device (SITVD) and Double Inlet Tubes Venturi Device (DITVD), we have reached the following conclusions: (1) In SITVD, the liquid flow field is biased to one side, whereas in DITVD, the liquid flows along the axial direction, resulting in bubbles experiencing stronger shear forces. (2) DITVD exhibits a higher overall gas holdup compared to SITVD, with an average axial gas holdup of 0.0317, which is greater than SITVD's 0.0247. However, SITVD's gas holdup is more evenly distributed. (3) SITVD exhibits a higher turbulence dissipation rate of 545 m2/s3, while the bubble residence time in DITVD is comparatively longer. (4) The average bubble diameter of DITVD is 1.116 mm, which is higher than the 1.011 mm of SITVD. (5) DITVD has better mass transfer than SITVD. The proposed structure of the new Venturi scrubber in this study demonstrates a significant enhancement in mass transfer capacity and filtration efficiency. This discovery provides a solid basis for the design and optimization of FCVS, thereby ensuring the safe operation of nuclear reactors.

Discovery of bubble accumulation behavior in catalyst layer of proton exchange membrane water electrolyzer

The presence of nano-scale oxygen bubble transport and accumulation within the anodic catalyst layer (CL) in proton exchange membrane water electrolyzer (PEMWE) remains controversial. In this study, we obtain several crucial evidence to resolve this debate using a Pt-coated mesh porous transport layer (PTL) as an oxygen sensor and with the help of multiple visualization methods. The evidence includes the oxygen reduction current detected from the anodic CL after electrolysis was stopped, continued bubble generation and growth on the CL surface when no oxygen evolution reaction happening in CL, and the gas outlet holes observed from the CL surface. The evidence supports that nano-scale oxygen bubble transport and accumulation indeed happen within anodic CL. The influence of characteristics of the CL on the reversible performance change induced by bubble accumulation behavior further reveals the possible mechanism of bubble transport in CL. The bubbles are generated at the entire CL, and its transport behavior is shaped by the porous structure of CL. Increasing the bubble transport distance, tortuosity, and pore hydrophobicity within the CL all lead to a significant increase in the rate and degree of bubble accumulation within the CL.

Energy-efficient bubble aeration guided by bubble dynamics model: From bubble formation at submerged orifice to oxygen utilization during uprising

Bubble aeration is a significant consumer of energy in wastewater treatment processes. Optimizing oxygen transfer, from an energy usage perspective, is crucial in the development of clean production techniques and for the stimulation of the circular economy. Although large efforts have been made in enhancing this process, particularly in ameliorating bubble diffusers, a main problem lies in energy wastage due to over-pursuing ultra-fine bubble generation. In this study, a dynamic model, that integrated both bubble expansion and detachment at submerged orifices, and consequential oxygen utilization during the uprising, was developed in order to better facilitate energy savings during the control of bubble generation. We demonstrate through calibrated models that bubble formation is governed by many factors including gas flow rate, orifice radius, surface tension, liquid viscosity, and surface wettability. Small bubbles are more prone to form when subjected to conditions of high wettability, small orifice size and low flow rate, since the bubbles are easily detached by the increasing upward forces in these scenarios. The oxygen transfer during the rising process was calculated as a function of bubble size, gas type and water depth. Bubbles with a radius smaller than a threshold value can shrink and collapse while below the water surface and thus provide 100% oxygen utilization. The threshold values of bubble radius are determined to be 150 μm and 250 μm at 5 m and 15 m initial water depth, respectively. The parameter set for bubble generation in order to obtain the desired bubble size may then be inversely determined by our bubble formation model, and it's considered as optimal aeration strategy to realize precise aeration. With these results, our study highlights the viability of the approach employing the proposed model in order to direct energy-efficient bubble generation.

Pool boiling performance for GaldenR HT 55 subject to smooth, pin fin, and sintered pin fin heat sink

The dielectric fluid of GaldenR HT 55 (Perfluoropolyether) is regarded as a potential candidate for two-phase immersion cooling since its boiling point at 1 atm is 55 °C which is quite suitable for electronics cooling. The fluid is of special interest since the main vender of dielectric fluid will no longer produce FGAS after 2024. However, very rare nucleate boiling performance data for HT55 were reported in the literature. The objective of this study aims to provide nucleate boiling performance data for various heat sinks applicable for nucleate boiling. The test samples include a smooth reference surface (#1), 2 pin fins (the pin diameters are 1 mm (#2) and 2 mm (#3), and 3 pin fin with various sintered coatings (powder size: 150–200 μm (#4), 200–250 μm (#5), and 250–350 μm (#6)). Heat flux spans from 80 to 600 kW/m2. HTC for small pin fin (#2) is marginally higher than that of smooth surface, and large pin fin (#3) shows about 40 % enhancement compared to smooth surface at 140 kW/m2. HTCs for sintered pin fins are much higher than those of pin fin or smooth surface with approximately 90–95 % enhancement relative to the smooth surface at low heat flux. The visual observations indicate that sample #6 yields the largest bubble departure diameter and departure frequency. Yet bubble generations are especially pronounced on top of the pin fin. The CHF of the tested surfaces are following the sequence: #5 > #6 > #4 > #3 > #2 > #1. The sample #5 contains a CHF over 600 kW/m2 which is about four times higher than that of the smooth surface.

Monodispersed Bubble Generation Using Hydrophobic Orifices: The Extended Tate's Law.

The use of submerged orifices for bubble generation is ubiquitous in industries with wettability known to influence the bubble departure diameter. In this study, we investigated bubble generation and departure from the orifices (0.3-2 mm) drilled on hydrophobic perfluoroalkoxy (PFA) tubes in water. By varying the gas inflow rate (33 to 200 mL/min), we found that the Sauter mean diameter closely matched those generated by hydrophilic quartz orifices. However, monodispersed bubbles were formed on the PFA tube compared to those on quartz with much wider size distributions. By examining the dynamic bubbling process, we confirmed its agreement with Tate's law, which was originally developed for quasi-steady conditions and emphasizes a balance between capillary and buoyancy forces. However, it should be noted that dynamic conditions lead to an increase in bubble volume compared to the quasi-steady condition despite following the same principle, which is explained by the continuous gas inflow when the bubble departs from the orifice at a necking stage. The above understandings enable generation of monodispersed bubbles under dynamic conditions, benefiting industries requiring precise control on bubble size, such as the bubble assisted wet etching and cleaning processes in semiconductor fabrication.

Freestream turbulence effects on low Reynolds number NACA 0012 airfoil laminar separation bubble and lift generation

Laminar separation bubbles (LSB's) over the suction surface of a wing at low Reynolds number (O(104)−O(106) based on the airfoil chord length) can significantly affect the aerodynamic performance of the wing, and pose a unique challenge for the predictive capabilities of simulation tools due to their high sensitivity to flow environments and wing surface conditions. In this work a series of two-dimensional (2D) and three-dimensional (3D) low-order, and high-order accurate unstructured-grid-based numerical methods with varying model fidelity levels were used to study LSB physics over a NACA 0012 airfoil both in a clean freestream and in a turbulent freestream at a chord-based Reynolds number of 12,000. Lift production and time-averaged flow fields were compared with available experimental results. A major discovery is that in clean freestream flow a 3D high-order numerical scheme is necessary to capture LSB physics. This is due to the sensitivity of LSB-induced laminar-turbulent transition to flow conditions and boundary geometry at low Reynolds number. In freestream flows with moderate background turbulence (∼5%), 2D simulations failed to capture subtle 3D flow physics due to their intrinsic limitation, but can reasonably predict time-averaged airfoil performance. Similarity and distinction between freestream vortex-LSB interaction in 2D and eddy-LSB interaction in 3D were explained. The role of the Kelvin-Helmholtz instability and Klebanoff modes in the transition of 3D airfoils were shown to be critical for understanding laminar-turbulent transition and LSB formation on airfoils in clean and turbulent freestreams.