Vortex Patterns Research Articles

Effect of catheter ablation on the hemodynamics of the left atrium : Hemodynamics of ablation.

This study aims to evaluate the impact of catheter ablation for atrial fibrillation (AF) on left atrial (LA) flow dynamics and geometrical changes. This exploratory study included computational flow simulations from 10 patients who underwent catheter ablation for AF. Complete cardiac cycle dataset was simulated before and after ablation using computational fluid dynamics. The study main endpoints were the changes in LA volume, LA velocity, LA wall shear stress (WSS), circulation (Γ), vorticity, pulmonary vein (PV) ostia area, and LA vortices before and after ablation. There was an average decrease in LA volume (11.58 ± 15.17%) and PV ostia area (16.6 ± 21.41%) after ablation. A non-uniform trend of velocity and WSS changes were observed after ablation. Compared with pre-ablation, 4 patients exhibited lower velocities, WSS distributions, and a decreased Γ (> 8.5%), while 6 developed higher velocities and WSS distributions. These geometrical changes dictated different flow mixing in the LA and distinct vortex patterns, characterized by different spinning velocities, vorticities, and rotational directions. Regions with q-criterion > 0 were found to be dominant in the LA, indicating prevalent rotational vortex structures. Catheter ablation for AF induced different geometrical changes on the LA and the PVs, therefore influencing flow mixing and vortex patterns in the LA, in addition to overall velocity and WSS distribution. Further exploration of the impact of catheter ablation on intracardiac flow dynamics is warranted to discern patterns that may correlate with clinical outcomes.

Topographic Stabilization of Ocean Rings

AbstractCoherent large‐scale vortices in the open ocean can retain their structure and properties for periods as long as several years. However, the patterns of potential vorticity in such vortices suggest that they are baroclinically unstable and therefore should rapidly disintegrate. This study proposes a plausible explanation of the longevity of large‐scale ocean rings based on bottom roughness, which restricts flow in the lower layer and thereby stabilizes the eddy. We perform a series of simulations in which topography is represented by the observationally derived Goff‐Jordan spectrum. We demonstrate that topography stabilizes coherent vortices and dramatically prolongs their lifespan. In contrast, the same vortices in the flat‐bottom model exhibit strong instability and fragmentation on the timescale of weeks. A critical depth variance exists that allows vortices to remain stable and circularly symmetric indefinitely. Our investigation underscores the essential role played by topography in the dynamics of large‐ and meso‐scale flows.

2-DOF vortex-induced vibration of rotating circular cylinder in shear flow

The vortex-induced vibration (VIV) of a rigid cylinder which can rotate counterclockwise in a plane linear shear flow is numerically simulated within the range of reduced velocity 3≤U*≤12. The rotating cylinder with two degrees of freedom (2-DOF) can vibrate freely in streamwise and cross-flow directions. The shear factors (λ) of the plane linear shear flow considered in this study are 0.05 and 0.1. The shear flow enhances the VIV of the 2-DOF rotating cylinder in two vibration directions. The maximum amplitude ratio of the rotating cylinder is 0.414D in the streamwise direction and 0.820D in the cross-flow direction. The amplitude ratio in the cross-flow direction (Ay/D) rises significantly with the increase of the shear factor. The Magnus effect caused by rotation enlarges the offset from the initial position of the rotating cylinder. The movement trajectory of the non-rotating cylinder in the shear flow presents a droplet-shape, which is obviously different from the "8"-shaped trajectory of uniform flow. The droplet-shaped trajectory of a closed-loop indicates that the non-rotating cylinder under the action of shear flow has the same vibration frequency in the two vibration directions. Three vortex patterns of 2S, P+S, and U can be captured in the wake of the rotating circular cylinder.

Large eddy simulation of the flow energy dissipation in the blade channels of a stalled pump impeller

Pump impellers usually work with the rotating stall phenomenon. The performance will be strongly affected by the undesirable flow. Understanding the features of flow energy dissipation is very important. In this study, large eddy simulation is conducted for the turbulent flow field based on a typical 6-blade pump impeller with “alternating stall” phenomenon. The stalled channels and well-behaved channels alternatively and stably distribute. Compared with the experimental data, the numerical simulation is proved accurate. In the well-behaved channel, flow pattern is relatively smooth. In the stalled channel, flow is completely blocked by several stall cells. Vortex shedding is well predicted mainly in three regions including the leading-edge region of stalled channel, the outlet region of stalled channel, and the blade suction side region of well-behaved channel. Turbulence kinetic energy is high in these regions. High flow energy dissipation is found among shedding vortexes due to flow-flow interaction and in the near-wall region because of flow-wall interaction. In the core region of vortexes, flow energy dissipation is not that high. The flow-flow interaction and the flow-wall interaction are two main sources of flow energy dissipation. In the well-behaved impeller blade channel with smooth flow pattern, the flow energy dissipation is mainly caused by flow-wall interaction. On the contrary, in the stalled impeller blade channel with vortical flow pattern, the flow energy dissipation is mainly caused by flow–flow interaction. The large eddy simulation-based study will be very helpful in enhancing the performance of pump impellers especially with the rotating stall phenomenon.

An investigation of chaotic mixing behavior in a planar microfluidic mixer

Achieving rapid mixing of different liquids in a short distance is important in various biochemical applications. Herein, a novel planar mixer with staggered Z-shaped baffles is proposed. Numerical investigations are carried out to evaluate its mixing ability based on mixing quality and pressure drop when the Reynolds number (Re) varies from 0.1 to 50. The Lyapunov exponent, the Poincaré map, and the vortex visualization are conducted to comprehensively analyze the chaotic state and the mixing mechanism. Results show that the proposed mixer exceeds 0.9 mixing efficiency when 0.1 ≤ Re and Re ≥ 8. As Re ≥ 8, different vortex patterns appear by changing the inlet configuration. The disturbance for fluids induced by a vortex on the mass transfer surface is not only dependent on its intensity but also related to the position of the vortex/vortex leg. The proposed planar mixer, inducing a single vortex or vortex pair with different directions, presents different mixing performance when the Re varies from 8 to 50, from which the approach of the rotating vortex that can mainly improve the mixing quality is found. This well explains the chaotic mixing behavior observed in the planar mixer with Z-shaped baffles, which to date has not been studied before. Furthermore, the micromixer is fabricated, tested, and applied for luminol–peroxide chemiluminescence detection to characterize its performance.

Amiodarone-Induced Multi-Systemic Toxicity Involving the Liver, Lungs, Thyroid, and Eyes: A Case Report

ObjectivesAmiodarone is widely used to treat arrhythmia. However, amiodarone is known for its severe toxicity to the liver, lungs, and thyroid. Amiodarone causes liver damage ranging from asymptomatic serum aminotransferase elevation to hepatic failure requiring liver transplantation. Although amiodarone toxicity has been reported, its simultaneous multi-organ toxicity is not well-known. Here, we introduce a novel case of multi-systemic amiodarone toxicity involving the liver, lungs, thyroid, and eyes.Case PresentationA 61-year-old woman visited the emergency room due to general weakness, nausea, visual disturbance, heat intolerance, and a non-productive cough. The patient had been using clopidogrel and amiodarone due to underlying atrial fibrillation. The total level of bilirubin was 0.71 mg/dL, aspartate aminotransferase was 358 U/L, alanine aminotransferase was 177 U/L, and prothrombin time was 27.1 s. Computed tomography showed diffuse increased liver intensity and scattered hyperattenuated nodular consolidations in both lungs. Transthoracic needle lung biopsy revealed fibrinoid interstitial inflammation with atypical change of type II pneumocytes and intra-alveolar foamy macrophages. In addition, the thyroid-stimulating hormone level was <0.008 μIU/mL, and free thyroxine was 4.67 ng/dL. The thyroid scan showed diffuse homogenous intake of technetium-99 m pertechnetate in both thyroid lobes. The ophthalmologic exam detected bilateral symmetrical corneal deposits in a vortex pattern. With these findings, we could diagnose amiodarone-induced hepatic, pulmonary, thyroid, and ophthalmologic toxicity. Liver function was restored after cessation of amiodarone, and thyroid function was normalized with methimazole administration. However, due to aggravated lung consolidations, systemic steroid treatment was administered, and improvement was seen 1 week after, at the follow-up exam. As her symptoms improved, she was discharged with a plan of steroid administration for 3 to 6 months.ConclusionsThis case implies the possibility of multi-systemic amiodarone toxicity. Thus, the toxicity of amiodarone to multiple organs must be monitored. Prompt cessation of the drug should be considered upon diagnosis.

Vorticity and Thermodynamics in a Gulf of Mexico Atmospheric River

This paper examines the interaction of tropical moisture with an atmospheric river. The analysis of this paper is focused mainly on dropsonde data collected during the fifth day of the Convective Processes Experiment (CPEX). An area of interest is chosen over the central Gulf of Mexico, where the remnant moisture of the tropical system Beatriz penetrated from the Eastern Pacific after making landfall in the western coast of Mexi-co. Results in this study show an eastward-tilting pattern of enhanced mid-level vorticity, coupled with high saturation fraction and low instability index in the predominantly stratiform regime present in the region. An inverse relation between saturation fraction and instability index, as indicated by moisture quasi-equilibrium (MQE), is found in a previously-dominant convective regime. Strong vertical shear signals that the vorticity pattern within this stratiform system is being advected poleward into mid-latitudes. Poleward-moving moisture plumes in narrow channels called atmospheric rivers (ARs) are observed during the mission. We provide insights into vorticity and MQE as conceptual tools to characterize the moisture mechanism of atmospheric rivers near the tropics, where the physical processes behind these river-like structures are less well-understood.

Investigation on flow and heat transfer in rectangular cross-section sinusoidal channels

In this paper, the flow and heat transfer characteristics in a sinusoidal rectangular channel are numerically probed. It's found that Dean vortex can be induced in sinusoidal rectangular channel, and the intensity of Dean vortex varies regularly with channel curvature. The intensity of Dean vortex in sinusoidal channels with various cross-sectional ratios, and the local Nusselt number at different locations are further investigated to reveal the variation pattern of Dean vortex and the corresponding variation in heat transfer capacity. In addition, it's found that the Dean vortex becomes unstable when the Reynolds number exceeds a critical value. The Dean instability balances the spatial inhomogeneity of wall heat transfer by means of fluctuations with the time. The critical Reynolds number corresponding to sinusoidal rectangular channels with various cross-sectional ratios is obtained by the helicity method, and the relationship between the cross-sectional ratio and critical Reynolds number is obtained as well.

Self-generated quantum gauge fields in arrays of Rydberg atoms

As shown in recent experiments (Lienhard et al 2020 Phys. Rev. X 10 021031), spin–orbit coupling in systems of Rydberg atoms can give rise to density-dependent Peierls phases in second-order hoppings of Rydberg spin excitations and nearest-neighbor repulsion. We here study theoretically a one-dimensional zig-zag ladder system of such spin–orbit coupled Rydberg atoms at half filling. The second-order hopping is shown to be associated with an effective gauge field, which in mean-field approximation is static and homogeneous. Beyond the mean-field level the gauge potential attains a transverse quantum component whose amplitude is dynamical and linked to density modulations. We here study the effects of this to the possible ground-state phases of the system. In a phase where strong repulsion leads to a density wave, we find that as a consequence of the induced quantum gauge field a regular pattern of current vortices is formed. However also in the absence of density–density interactions the quantum gauge field attains a non-vanishing amplitude. Above a certain critical strength of the second-order hopping the energy gain due to gauge-field induced transport overcomes the energy cost from the associated build-up of density modulations leading to a spontaneous generation of the quantum gauge field.

Examining the Kinematic Structures within which Lightning Flashes Are Initiated Using a Cloud-Resolving Model

Abstract Lightning is frequently initiated within the convective regions of thunderstorms, and so flash rates tend to follow trends in updraft speed and volume. It has been suggested that lightning production is linked to the turbulent flow generated by updrafts as turbulent eddies organize charged hydrometeors into complex charge structures. These complex charge structures consist of local regions of increased charge magnitudes between which flash-initiating electric fields may be generated. How turbulent kinematics influences lightning production, however, remains unclear. In this study, lightning flashes produced in a multicell and two supercell storms simulated using The Collaborative Model for Multiscale Atmospheric Simulation (COMMAS) were examined to identify the kinematic flow structures within which they occurred. By relating the structures of updrafts to thermals, initiated lightning flashes were expected to be located where the rate of strain and rotational flow are equal, or between updraft and eddy flow features. Results showed that the average lightning flash is initiated in kinematic flow structures dominated by vortical flow patterns, similar to those of thermals, and the structures’ kinematics are characterized by horizontal vorticity and vertical shearing. These kinematic features were common across all cases and demonstrated that where flash-initiating electric fields are generated is along the periphery of updrafts where turbulent eddies are produced. Careful consideration of flow structures near initiated flashes is consistent with those of thermals rising through a storm.

Numerical investigation of hemodynamic pattern in carotid artery dynamic aneurysm on bifurcation region for early clinical decision making

AbstractIn this paper, a numerical estimation of wall shear stress (WSS) and study on hemodynamic pattern in carotid artery (CA) near the bifurcation region with dynamic growth of aneurysm using computational fluid dynamics (CFD) for making early clinical decision is presented. Aneurysm in the carotid artery affects the blood supply to brain and if it is untreated at early stage may lead to sudden death. Computed tomography images of four different cases of stroke subjects scanned of 600 slices with 1 mm resolution with neighbouring layers from neck to head are considered for this study. Numerically a CA with bifurcation region is developed from these images and aneurysm is and allowed to grow dynamically from 10 to 20 mm. WSS and hemodynamic pattern is estimated numerically using Ansys platform at various region of interest in both rigid and compliant wall conditions. The arterial wall thinning was analytically estimated using thick cylinder theory to estimate the increase in aneurysm under various stress conditions (rest and exercise conditions). The findings show that WSS is found to reduce at the aneurysm region with a corresponding strong vortex pattern. Thus, the vortex pattern could be the cause of tissue damage and thinning rather than WSS. The corresponding increase in velocity gradient at the bifurcation region is also captured. This high gradient is the cause for higher WSS at the bifurcation region which is a possible cause for the formation of plaque and arteriosclerosis. It is interesting to note that the WSS did not change drastically for 10 and 15 mm aneurysm but a large change was seen from normal to 10 and 15–20 mm respectively. This study provides a better clinical insight on the effect of aneurysm in CA bifurcation region using a systematic approach to numerical modelling compared to traditional imaging modalities. It can be used as an adjunct tool for physicians and surgeons for planning necessary clinical interventions.

Role of double-subduction dynamics in the topographic evolution of the Sunda Plate

SUMMARY The Sunda Plate has shaped itself in a complex tectonic framework, driven by the interactions of multiple subduction zones in its history. Using thermomechanical computational fluid dynamic models we show in this paper how the in-dip double-subduction dynamics has controlled the first-order 3-D topography of this plate, currently bounded by two major N–S trending active trenches: Andaman–Sumatra–Java and Philippines on its western and eastern margins, respectively. We consider six E–W transects to account for an along-trench variation of the subduction parameters: subduction rate (Vc), shallow-depth (200–300 km) slab dip (α) and intertrench distance (ITD, λ) in our 2-D numerical experiments. The deviatoric stress fields and the topographic patterns are found to strongly depend on λ. For large ITDs (λ = 2000–3000 km), the overriding plate develops dominantly tensile stresses in its central zone, forming low topographic elevations. Decreasing λ results in a transition from extensional to contractional deformation, and promotes topographic uplift in the southern part. We explain these effects of λ in terms of the sublithospheric flow vortex patterns produced by the subducting slabs. Large λ (&amp;gt; 2000 km) generates non-interacting flow vortices, located close to the two trenches, leaving the mantle region beneath the overriding plate weakly perturbed. In contrast, small λ results in their strong interaction to produce a single upwelling zone, which facilitates the overriding plate to gain a higher topographic elevation. The stress field predicted from our model is validated with the observed stress patterns. We also interpolate a 3-D topographic surface and vertical uplift rates from the serial model sections, and compare them with the observed surface topography of the Sunda Plate.

Non-Newtonian fluid flow over a rotating elliptic cylinder in laminar flow regime

In this paper, a numerical investigation is done to understand the two-dimensional flow behaviorof power-law fluids past a rotating elliptic cylinder in unconfined domain. The flow field around the cylinder is calculated using ANSYS (FLUENT 15) The sliding mesh method (SMM) is used to treat moving solid–fluid boundary. The engineering parameters like drag coefficient, lift coefficient and complete kinematic variables such as stream function and vorticity have been calculated for the range of dimensionless parameters namely aspect ratio of the cylinder e=0.1 and 0.7, rotational speed (1≤α≤4), Reynolds number (5≤Re≤40) and power-law index (0.4≤n≤1.8). The emphasis has been given to see the effect of the power-law index (n) and Reynolds number (Re), rotational speed α and aspect ratio of cylinder e on flow characteristics around the cylinder in laminar flow regime. Before presenting the results, a qualitative as well as a quantitative comparison has been done between the present result and experimental and numerical result presented in the literature. Further, a detailed streamline and vorticity patterns in the vicinity of the cylinder is shown to demonstrate the wake formation phenomenon around the cylinder. The increase in rotational speed and power-law index exhibit a similar effect on wake formation phenomena. Due to rotational motion of the cylinder drag and lift coefficient vary in periodic manner with time/orientation of cylinder. The average value of drag is seen to decrease with Re and α and a complete trend is displayed with power-law index, n. The negative lift coefficient is observed due to anticlockwise motion of the cylinder for all parameters considered here. The results of this work clearly show the strong dependency of flow phenomenon around the rotating elliptic cylinder on power-law index, rotational speed, aspect ratio, and Reynolds number.

Using difference modelling and computational fluid dynamics to investigate the evolution of complex, tidally influenced shipwreck sites

The large number of historic metal-hulled shipwrecks on the seabed is a major consideration for the marine environment, heritage management and spatial planning. Their stability is driven by linked hydro- and sediment-dynamics, which in turn influence chemical corrosion and biological encrustation. The dynamism at underwater sites is frequently expressed in elaborate patterns of depositional and erosional features developed due to seabed scour. These settings are complex, due to the variable morphologies of the wrecks, and diverse types of seabed geology and geomorphology. Not only are the flow patterns and geomorphic changes at shipwreck sites not fully understood, but how these influence the wreck structures remains under-researched. Here we combine high-resolution multibeam echosounder, ocean current and sediment data with 3D Computational Fluid Dynamics (CFD) to investigate interrelations between hydro- and sediment-dynamics and the deterioration of two complex, fully submerged tidally-influenced shipwrecks. Intricate patterns of wake and horseshoe vortices are observed, and modelled wall shear stresses predict geomorphic changes recorded in 4-year and one-week interval difference models. Moreover, substantial damage is detected on the wrecks, correlated with areas of elevated wall shear stress and pressure in CFD simulations. The combined approach aids site management and provides analogies for offshore engineering.

Three-Dimensional Hydrostatic Curved Channel Flow Simulations Using Non-Staggered Triangular Grids

Non-staggered triangular grids have many advantages in performing river or ocean modeling with the finite-volume method. However, horizontal divergence errors may occur, especially in large-scale hydrostatic calculations with centrifugal acceleration. This paper proposes an unstructured finite-volume method with a filtered scheme to mitigate the divergence noise and avoid further influencing the velocities and water elevation. In hydrostatic pressure calculations, we apply the proposed method to three-dimensional curved channel flows. Approximations reduce the numerical errors after filtering the horizontal divergence operator, and the approximation is second-order accurate. Numerical results for the channel flow accurately calculate the velocity profile and surface elevation at different Froude numbers. Moreover, secondary flow features such as the vortex pattern and its movement along the channel sections are also well captured.

Evolution of high-frequency instabilities in the presence of azimuthally compact crossflow vortex pattern over a yawed cone

Evolution of high-frequency instabilities in the presence of azimuthally compact crossflow vortex pattern over a yawed cone

Evaporation-induced convective transport in confined saline droplets

Here, we report on the convection pattern, inside a confined saline droplet sandwiched between two hydrophobic substrates, before crystallization (prenucleation) and at the onset of crystallization (postnucleation). Crystallization occurs inside a saline droplet due to evaporation-induced supersaturation of the droplet. The hydrophobic nature of the substrates leads to the crystallization at a single nucleation site at the triple contact line of the droplet or in the interior of the droplet. The flow field in the prenucleation and the postnucleation stages is attributed to the density gradient established inside the droplet during evaporation and subsequent crystallization. A stark contrast in the convective flow patterns and the flow strength is observed between the two stages of evaporation. While the prenucleation regime is marked by an axisymmetric toroidal vortex pattern, the symmetry breaks in the postnucleation regime. Once the nucleation of crystal initiates, a recirculating flow field directed upward from the location of nucleation, and a 3–4-fold increase in the magnitude of flow velocity is observed. This increase in flow strength is attributed to the large difference in the local concentration arising because of nucleation. In addition, prior to nucleation, the change in the magnitude of maximum velocity is marginal (~10%) over an evaporation time of ~15 min. In contrast, the flow strength reduces appreciably with evaporation time (~ 45% over 15 min) in the postnucleation stage due to the growth of the crystal that in turn lowers the solutal concentration inside the droplet. We present a numerical model to determine the flow field inside the droplet in the postnucleation regime by introducing a sink term, accounting for crystallization-induced-depletion of solute, in the species transport equation and show that it agrees well with the experimental observation.

Dynamic Pattern Formation of Active Matters Triggered by Mechanical Stimuli.

In vitro gliding assay of the filamentous protein microtubule (MT) on a kinesin motor protein coated surface has appeared as a classic platform for studying active matters. At high densities, the gliding MTs spontaneously align and self-organize into fascinating large-scale patterns. Application of mechanical stimuli e.g., stretching stimuli to the MTs gliding on a kinesin-coated surface can modulate their self-organization and patterns according to the boundary conditions. Depending on the mode of stretching, MT at high densities change their moving direction and exhibit various kinds of patterns such as stream, zigzag and vortex pattern. In this chapter, we discuss detail procedures on how to apply mechanical stimuli to the moving MTs on a kinesin coated substrate.

Hemodynamic Parameters for Cardiovascular System in 4D Flow MRI: Mathematical Definition and Clinical Applications.

Blood flow imaging becomes an emerging trend in cardiology with the recent progress in computer technology. It not only visualizes colorful flow velocity streamlines but also quantifies the mechanical stress on cardiovascular structures; thus, it can provide the detailed inspections of the pathophysiology of diseases and predict the prognosis of cardiovascular functions. Clinical applications include the comprehensive assessment of hemodynamics and cardiac functions in echocardiography vector flow mapping (VFM), 4D flow MRI, and surgical planning as a simulation medicine in computational fluid dynamics (CFD).For evaluation of the hemodynamics, novel mathematically derived parameters obtained using measured velocity distributions are essential. Among them, the traditional and typical parameters are wall shear stress (WSS) and its related parameters. These parameters indicate the mechanical damages to endothelial cells, resulting in degenerative intimal change in vascular diseases. Apart from WSS, there are abundant parameters that describe the strength of the vortical and/or helical flow patterns. For instance, vorticity, enstrophy, and circulation indicate the rotating flow strength or power of 2D vortical flows. In addition, helicity, which is defined as the cross-linking number of the vortex filaments, indicates the 3D helical flow strength and adequately describes the turbulent flow in the aortic root in cases with complicated anatomies. For the description of turbulence caused by the diseased flow, there exist two types of parameters based on completely different concepts, namely: energy loss (EL) and turbulent kinetic energy (TKE). EL is the dissipated energy with blood viscosity and evaluates the cardiac workload related to the prognosis of heart failure. TKE describes the fluctuation in kinetic energy during turbulence, which describes the severity of the diseases that cause jet flow. These parameters are based on intuitive and clear physiological concepts, and are suitable for in vivo flow measurements using inner velocity profiles.

Bubble Dynamics and Nucleate Pool Boiling of Natural Convection

The phenomenon of nuclear boiling has always been recognized suitable for heat transfer between different boiling regimes. Study on boiling is considered as a new field which meets different research and industrial needs such as heat transfer in nuclear reactors, cooling units, rocket motors, electronic equipment cooling, batteries, etc. In this study, a chamber with immiscible fluid, water, steam, and air, having a side wall with uniform heat flux has been studied in 3D. To do so, we first considered the prediction of the heat flux interval for which the boiling occurs in the form of nuclear boiling. In this study, two-phase fluid volume (VOF) approach was used for modelling boiling on the vertical wall and two-phase flow. In this research, Ansys software package was used for numerical modelling and numerical simulation. Distribution of the velocity field follows more uniform pattern in dimensionless heights less than 0.9. In this study, bubbles are only present near a wall with heat flux that has a lower Rayleigh number. Also, existence of these bubbles on the wall, which prevents fluid infiltration, affects vortices caused by natural convection. However, the general and uniform patterns of vortices remain unchanged in most part of the fluid, which is because of the limited amount of bubbles near the wall with heat flux. Natural convection increases the height of fluid inside the chamber, which leads to the formation of stronger vortices at a dimensionless height of 0.9 that has a high Raleigh number due to high heat flux. In this case, the continuous use of heat flux gives rise to the production of bubbles over time.