Wave Breakup Research Articles

The entrainment mechanism and droplet size distribution in gas-liquid churn flow

Knowledge of entrained liquid is important in calculation of pressure drop and in the determination of the film flow rate and thence its dryout and consequent deterioration in heat transfer in heating systems. Note that the excessive liquid entrainment may cause the liquid film completely removed from the wall (dryout), which could lead to disastrous accident. As one of the least understood gas-liquid flow regimes, churn flow appears a highly-disturbed flow of gas and liquid. According to the observation, churn flow is characterized by huge waves with flow reversal between the waves and the highly oscillatory liquid film, which is accompanied a continuous gas core with considered amount of entrained liquid. Although there have been enduring efforts to show that the entrained fraction is high in churn flow and reaches the minimum around the churn/annular transition, the underlying mechanisms of droplet entrainment in churn flow are still not well explored. Additionally, there is a dearth of data about entrained droplets in churn flow due to its chaotic nature. The measurement techniques which are suitable to determine entrained droplets in annular flow have limitations when applied to churn flow because they might not be able to distinguish between liquid carried as droplets and that transported in huge waves. In this study, we focused on the entrainment mechanism, liquid distribution and droplet size distribution under churn flow condition. The high-speed camera and the high-resolution camera were employed to capture a more detailed description of the huge wave breakup and the liquid distribution in the cross-section of the pipe with the inner diameter of 19 mm. In order to obtain the high-resolution images of entrained droplets, a delicate shadow detecting method was developed in the present paper, which provides a reliable approach to capture the entrained droplets with various sizes. Subsequently, Matlab was employed to analyze the complete series of pictures and recognize each of the blobs. The blobs were interpreted as droplets after the sharpness was satisfied. Every accepted edge datum is considered to be a droplet and thus its diameter can be obtained by Image J. The results indicate that there are three mechanisms for droplet generation in churn flow: liquid bridge breakup dominants at slug/churn transition, bag breakup plays a dominant role at low gas superficial velocities, but ligament breakup comes to gain greater importance with the increase of gas flow rate. Accordingly, the amount of liquid entrained is high in the chaotic churn flow regime and gradually decreases during the transition from churn flow to annular flow and finally reaches a minimum around the churn/annular transition boundary. Detailed process of droplet entrainment was also provided. Based on observation, large droplets (chunks) are related to the breakdown of slugs and bag breakup mechanism, whereas smaller droplets can be ascribed to the breakup of chunks, ligament breakup. No doubt, the present paper helps understand the mechanism of the entrainment in churn flow, which is essential for the development of mechanistic models to predict the pressure drop and dryout condition.

A large eddy simulation of the breakup and atomization of a liquid jet into a cross turbulent flow at various spray conditions

A three-dimensional large eddy simulation (LES) is conducted to investigate the breakup and atomization of a liquid jet into a cross turbulent flow for several variants of a liquid-gas momentum flux ratio by varying the liquid injection velocity and cross flow temperature. The spray-field dynamics are treated using a combined Eulerian-Lagrangian approach in which the gas phase is discretized using a density-based, finite-volume approach. A Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) hybrid wave breakup model is implemented to simulate the liquid column and droplet breakup process. While the KH model is applied to the liquid column breakup (primary breakup), the RT model is implemented to the breakup of the small droplets (secondary breakup). The detail flow structures of the counter-rotating vortex pair (CVP) and vortex interaction behind the injector are observed. The spray penetration depth in the crossflow compares well with the experimental data and similar to empirical equations. The Sauter mean diameter (SMD) distribution is analyzed along the flow downstream representing somewhat different, and an analytical correlation model is proposed to pre-evaluate the SMD in the flowfield.

Robustness of free and pinned spiral waves against breakup by electrical forcing in excitable chemical media.

We present an investigation on the breakup of free and pinned spiral waves under an applied electrical current in the Belousov-Zhabotinsky reaction. Spiral fronts propagating towards the negative electrode are decelerated. A breakup of the spiral waves occurs when some segments of the fronts are stopped by a sufficiently strong electrical current. In the absence of obstacles (i.e., free spiral waves), the critical value of the electrical current for the wave breakup increases with the excitability of the medium. For spiral waves pinned to circular obstacles, the critical electrical current increases with the obstacle diameter. Analysis of spiral dynamics shows that the enhancement of the robustness against the breakup of both free and pinned spiral waves is originated by the increment of wave speed when either the excitability is strengthened or the obstacle size is enlarged. The experimental findings are reproduced by numerical simulations using the Oregonator model. In addition, the simulations reveal that the robustness against the forced breakup increases with the activator level in both cases of free and pinned spiral waves.

Time-linearized, compact methods for the inviscid GRLW equation subject to initial Gaussian conditions

• Effects of the width of initial Gaussian conditions on wave propagation are studied. • Roles of nonlinearity and local advection on wave dynamics are investigated. • Time-linearization methods for the GRLW equation are presented. • Rarefaction waves may appear behind solitary waves. • Localized dispersive oscillations may occur behind the leading wave. The objective of this paper is three-fold. First, four time-linearization methods that are second- and fourth-order accurate in time and space, respectively, are presented and used to study the dynamics of the modified and generalized regularized-long wave equations (mRLW and GRLW equations, respectively). Two of the methods use the conservation-law form of the equations and treat the wave amplitude and its second-order spatial derivative and the linear and nonlinear advection fluxes as unknowns, whereas the other two employ the non-conservation-law form of the equations and consider the wave amplitude and its first- and second-order spatial derivatives as unknowns. The methods employ three-point fourth-order accurate Padé discretizations for the first- and second-order derivatives, are second-order accurate in time, and yield linear systems of blocktridiagonal matrices. Second, the accuracy of these methods is assessed by comparing their results with those of the exact solution of the mRLW equation. It is reported that the four methods predict nearly the same values of the three invariants and have the same accuracy, and that an accurate prediction of the invariants may not correspond to small errors in space and time. Third, the dynamics of the inviscid GRLW equation is studied first qualitatively in terms of length and time scales and then numerically as a function of the linear advection speed, the exponent of the nonlinear advection flux, the dispersion coefficient and the amplitude and width of the initial bell-shaped or Gaussian conditions. It is shown that wide initial conditions result in wave steepening and breakup and the formation of solitary waves whose amplitude and speed decrease as the time for their formation increases. For narrow initial conditions, it is shown that only a single solitary wave may form. Behind this wave and depending on the parameters that characterized the inviscid GRLW equation, rarefaction or negative amplitude waves that propagate towards the upstream boundary or a train of localized oscillatory waves that do not emerge from the trailing edge of the leading solitary wave may be formed. These oscillatory waves exhibit the characteristics of, but are not dispersive shock waves and their amplitude and frequency increases as the width of the initial conditions is decreased. The results presented here do not only complement previous work by the authors, they also show that the dynamics of the inviscid GRLW equation undergoes new and interesting phenomena as the width of the initial conditions is decreased.

Suppression of Spiral Breakup in Excitable Media by Local Periodic Forcing

Lowered excitability leads to unstable meandering of spiral tip, which result in breakup of spiral waves into chaotic states induced by Doppler effects. This phenomenon is responsible for the transition from tachycardia to ventricular fibrillation in cardiac tissues. Numerical simulations show that low-energy local periodic forcing (LPF) applied around spiral tip can efficiently suppress the meandering behavior and consequently prevent spiral breakup. The controllable phase diagrams that describe the amplitude and period of LPF against excitability parameter are presented to illustrate the control region. The underlying mechanism of suppressing spiral meandering behavior is explored by greatly decreasing the radius of the meandering tip. The proposed scheme can potentially contribute to controlling cardiac arrhythmia.

Numerical investigation of turbulent-jet primary breakup using one-dimensional turbulence

Primary breakup to form droplets at liquid surfaces is an important fundamental process to study as it determines the initial properties of the dispersed phase, which affect mixing rates, secondary breakup, droplet collisions, and flow separation within the dispersed flow region. Primary breakup can be regarded as one of the least developed model components for simulating and predicting liquid jet breakup. However, it is of paramount importance in many technical applications, e.g. fuel injection in engines and spray painting. This paper presents a numerical investigation of primary breakup of a turbulent liquid jet in still air at standard conditions using the one-dimensional turbulence (ODT) modeling framework. ODT is a stochastic model that simulates turbulent flow evolution along a notional 1D line of sight by applying instantaneous maps to represent the effect of individual turbulent eddies on property profiles. An important feature of ODT is the resolution of all relevant scales, both temporal and spatial. The restriction to one spatial dimension in ODT permits affordable high resolution of interfacial and single-phase property gradients, which is key to capturing the local behavior of the breakup process and allows simulations at high Reynolds and Weber numbers that are currently not accessible to direct numerical simulations (DNS).This paper summarizes our extensions of the ODT model to simulate geometrically simple jet breakup problems, including representations of Rayleigh wave breakup, turbulent breakup, and shear-driven breakup. Each jet breakup simulation consists of a short temporal channel section to initialize a turbulent velocity profile at the nozzle exit followed by an adjacent jet section. The simulations are carried out for jet exit Reynolds number of 11,500, 23,000, 46,000 and 92,000 while the Weber number is varied within the range 102–107. We present results on breakup statistics including spatial locations of droplet release, droplet sizes and liquid core length. The results on primary breakup are compared to experimental results and models.

Spontaneous spiral wave breakup caused by pinning to the tissue defect

The work presents a mechanism of spiral wave initiation due to the specific boundary conditions on a border of cardiac tissue defect. There are known scenarios when anatomical or functional defects in cardiac tissue may provoke the spiral wave origination, including unidirectional blockage while passing through the narrow gates, bent over critical curvature wave fronts, inhomogeneous recovery of the tissue, etc. We show a new scenario of spiral wave breakup on a small defect, which is unexcitable but permeable for ionic currents supporting the excitation wave. It was believed that such defects stabilize the rotating wave; however, as shown, instead of stabilizing it leads to the spiral breakup and subsequent multiplication of the rotating waves.

A Parsimonious Model of the Rabbit Action Potential Elucidates the Minimal Physiological Requirements for Alternans and Spiral Wave Breakup.

Elucidating the underlying mechanisms of fatal cardiac arrhythmias requires a tight integration of electrophysiological experiments, models, and theory. Existing models of transmembrane action potential (AP) are complex (resulting in over parameterization) and varied (leading to dissimilar predictions). Thus, simpler models are needed to elucidate the “minimal physiological requirements” to reproduce significant observable phenomena using as few parameters as possible. Moreover, models have been derived from experimental studies from a variety of species under a range of environmental conditions (for example, all existing rabbit AP models incorporate a formulation of the rapid sodium current, INa, based on 30 year old data from chick embryo cell aggregates). Here we develop a simple “parsimonious” rabbit AP model that is mathematically identifiable (i.e., not over parameterized) by combining a novel Hodgkin-Huxley formulation of INa with a phenomenological model of repolarization similar to the voltage dependent, time-independent rectifying outward potassium current (IK). The model was calibrated using the following experimental data sets measured from the same species (rabbit) under physiological conditions: dynamic current-voltage (I-V) relationships during the AP upstroke; rapid recovery of AP excitability during the relative refractory period; and steady-state INa inactivation via voltage clamp. Simulations reproduced several important “emergent” phenomena including cellular alternans at rates > 250 bpm as observed in rabbit myocytes, reentrant spiral waves as observed on the surface of the rabbit heart, and spiral wave breakup. Model variants were studied which elucidated the minimal requirements for alternans and spiral wave break up, namely the kinetics of INa inactivation and the non-linear rectification of IK.The simplicity of the model, and the fact that its parameters have physiological meaning, make it ideal for engendering generalizable mechanistic insight and should provide a solid “building-block” to generate more detailed ionic models to represent complex rabbit electrophysiology.

Digital image communication scheme based on the breakup of spiral waves

Abstract A digital image communication scheme based on the breakup of spiral waves is presented in this paper. This communication system does not require spatially homogeneous random initial conditions. Moreover, the secret image is not embedded into the initial conditions of the evolving self-organizing patterns. Such features increase the security of the communication, but still enable an effective transmission of the secret image. Computational experiments are used to demonstrate the properties and efficiency of the proposed scheme.

Modeling of Effervescent Spray with Secondary Atomization within a Furnace

Objective: To analyze the droplet distribution characteristics of an effervescent injector by using kerosene within a furnace. Approach: A computational approach has been adopted to study and analyze the droplet distribution statistics. For primary breakup, effervescent injector model has been used and for secondary atomization, the WAVE breakup model has been adopted. Euler-Lagrange frame is employed to simulate the interaction between gas phase and droplet phase. Contributions: In this work, the effect of the variation of model constant C 2 of WAVE breakup model on droplet distribution has been studied. Around 30000 droplet samples are collected for each case (at different value of C 2 ). Validation of the work has been done with the literature available. Findings: However it has been observed that at the minimal and maximal droplet size is predicted well at radial positions away from the axis at any C 2 . The similar trend has been found for the Sauter Mean Diameter (SMD). However near the axis, the prediction is not good enough irrespective of any C 2 . Also it has been found that with higher value of C2, the computational results deviates much from the measured value.

Study of the Liquid Breakup Process in Solid Rocket Motor

In a solid rocket motor, when the aluminum based propellant combusts, the fuel is oxidized into alumina (). It tends to agglomerate into molten droplets, impinge on the chamber walls, and then flow along the nozzle wall. Such agglomerates cause erosive damage. The focus of the current research is to characterize the agglomerate flow within the nozzle section by studying the breakup process of the liquid film that flows along the wall of a straight test channel while a relatively higher-speed gas moves over it. We have used an unsteady-flow Reynolds-averaged Navier–Stokes code to investigate the interaction of the liquid film flow with the gas flow. The rate of the wave breakup was characterized by introducing breakup length, Ohnesorge number, and Weber number for various flow conditions. Based on the volume fraction of the liquid, these three numbers are indicators of the level of liquid breakup. We summarize that a larger breakup length relates to a high breakup state of the liquid because the appearance of droplets contributes to a larger total boundary length during calculation.

A modification to the WAVE breakup model for evaporating diesel spray

In order to improve the accuracy of the WAVE breakup model for an evaporating spray, it was calibrated using a series of diesel spray experiments with different orifice diameters, injection pressures, background gas densities and temperatures. The calibration focused on liquid length and spray (vapor) penetration. Based on the calibration results, it is concluded that the standard WAVE model with a constant C2, which is an adjustment parameter for breakup time, accurately predicts liquid length and spray penetration with a variety of orifice diameters, injection pressures and background gas densities. However, the same cannot be said for background temperature. Background temperature strongly affects the C2 value. Particularly, the C2 decreases with an increase in background temperature. Interestingly, the relationship between the C2 value and the background temperature seems to be of approximate inverse proportion. Therefore, due to this relationship between the C2 value and background temperature, and in order to obtain greater simulation accuracy, the proposed WAVE model with a variable C2 was developed and used to simulate a single-cylinder diesel engine. It was found that there is a significant decrease in liquid length alongside the development of the in-cylinder spray and combustion process. This is reasonable because liquid droplets break-up and evaporate faster in a higher temperature environment. Moreover, the result is in accordance with images from optical diesel engine experiments captured and performed by others.

Electrophysiology of Heart Failure Using a Rabbit Model: From the Failing Myocyte to Ventricular Fibrillation.

Heart failure is a leading cause of death, yet its underlying electrophysiological (EP) mechanisms are not well understood. In this study, we use a multiscale approach to analyze a model of heart failure and connect its results to features of the electrocardiogram (ECG). The heart failure model is derived by modifying a previously validated electrophysiology model for a healthy rabbit heart. Specifically, in accordance with the heart failure literature, we modified the cell EP by changing both membrane currents and calcium handling. At the tissue level, we modeled the increased gap junction lateralization and lower conduction velocity due to downregulation of Connexin 43. At the biventricular level, we reduced the apex-to-base and transmural gradients of action potential duration (APD). The failing cell model was first validated by reproducing the longer action potential, slower and lower calcium transient, and earlier alternans characteristic of heart failure EP. Subsequently, we compared the electrical wave propagation in one dimensional cables of healthy and failing cells. The validated cell model was then used to simulate the EP of heart failure in an anatomically accurate biventricular rabbit model. As pacing cycle length decreases, both the normal and failing heart develop T-wave alternans, but only the failing heart shows QRS alternans (although moderate) at rapid pacing. Moreover, T-wave alternans is significantly more pronounced in the failing heart. At rapid pacing, APD maps show areas of conduction block in the failing heart. Finally, accelerated pacing initiated wave reentry and breakup in the failing heart. Further, the onset of VF was not observed with an upregulation of SERCA, a potential drug therapy, using the same protocol. The changes introduced at the cell and tissue level have increased the failing heart’s susceptibility to dynamic instabilities and arrhythmias under rapid pacing. However, the observed increase in arrhythmogenic potential is not due to a steepening of the restitution curve (not present in our model), but rather to a novel blocking mechanism.

On the accuracy of some explicit and implicit methods for the inviscid GRLW equation subject to initial Gaussian conditions

Purpose – The purpose of this paper is to both determine the effects of the nonlinearity on the wave dynamics and assess the temporal and spatial accuracy of five finite difference methods for the solution of the inviscid generalized regularized long-wave (GRLW) equation subject to initial Gaussian conditions. Design/methodology/approach – Two implicit second- and fourth-order accurate finite difference methods and three Runge-Kutta procedures are introduced. The methods employ a new dependent variable which contains the wave amplitude and its second-order spatial derivative. Numerical experiments are reported for several temporal and spatial step sizes in order to assess their accuracy and the preservation of the first two invariants of the inviscid GRLW equation as functions of the spatial and temporal orders of accuracy, and thus determine the conditions under which grid-independent results are obtained. Findings – It has been found that the steepening of the wave increase as the nonlinearity exponent is increased and that the accuracy of the fourth-order Runge-Kutta method is comparable to that of a second-order implicit procedure for time steps smaller than 100th, and that only the fourth-order compact method is almost grid-independent if the time step is on the order of 1,000th and more than 5,000 grid points are used, because of the initial steepening of the initial profile, wave breakup and solitary wave propagation. Originality/value – This is the first study where an accuracy assessment of wave breakup of the inviscid GRLW equation subject to initial Gaussian conditions is reported.

Dynamics of Scroll Wave in a Three-Dimensional System with Changing Gradient.

The dynamics of a scroll wave in an excitable medium with gradient excitability is studied in detail. Three parameter regimes can be distinguished by the degree of gradient. For a small gradient, the system reaches a simple rotating synchronization. In this regime, the rigid rotating velocity of spiral waves is maximal in the layers with the highest filament twist. As the excitability gradient increases, the scroll wave evolutes into a meandering synchronous state. This transition is accompanied by a variation in twisting rate. Filament twisting may prevent the breakup of spiral waves in the bottom layers with a low excitability with which a spiral breaks in a 2D medium. When the gradient is large enough, the twisted filament breaks up, which results in a semi-turbulent state where the lower part is turbulent while the upper part contains a scroll wave with a low twisting filament.

Multi-dimensional dynamics of stimulated Brillouin scattering in a laser speckle: Ion acoustic wave bowing, breakup, and laser-seeded two-ion-wave decay

Two- and three-dimensional particle-in-cell simulations of stimulated Brillouin scattering (SBS) in laser speckle geometry have been analyzed to evaluate the relative importance of competing nonlinear processes in the evolution and saturation of SBS. It is found that ion-trapping-induced wavefront bowing and breakup of ion acoustic waves (IAW) and the associated side-loss of trapped ions dominate electron-trapping-induced IAW wavefront bowing and breakup, as well as the two-ion-wave decay instability over a range of ZTe/Ti conditions and incident laser intensities. In the simulations, the latter instability does not govern the nonlinear saturation of SBS; however, evidence of two-ion-wave decay is seen, appearing as a modulation of the ion acoustic wavefronts. This modulation is periodic in the laser polarization plane, anti-symmetric across the speckle axis, and of a wavenumber matching that of the incident laser pulse. A simple analytic model is provided for how spatial “imprinting” from a high frequency inhomogeneity (in this case, the density modulation from the laser) in an unstable system with continuum eigenmodes can selectively amplify modes with wavenumbers that match that of the inhomogeneity.

Computational simulations of the effects of the G229D KCNQ1 mutation on human atrial fibrillation.

Atrial fibrillation (AF) is related to mutations at the genetic level. This includes mutations in genes that encode KCNQ1, a subunit of the I Ks channel. Here, we investigate the mechanism of gain-of-function in I Ks towards the occurrence of AF. We used the Courtemanche-Ramirez-Nattel (CRN) human atrial cell model (Am J Physiol Heart Circ Physiol 275:H301-H321, 1998) and applied the modification proposed by Hasegawa et al. (Heart Rhythm 11:67-75, 2014) to fit the behavior of I Ks due to the G229D mutation in KCNQ1 under a heterozygous mutant form. This was incorporated into two-(2D) and three-dimensional (3D) tissue models, where the mutation sustained a reentrant wave. However, under the wild-type condition, the reentrant wave terminated before the end of our simulations (in 2D, the spiral wave terminated before 10s, while in 3D, the spiral wave terminated before 13s). Sustained reentry under the mutation conditions also resulted in a spiral wave breakup in the 3D model, which was sustained until the end of the simulation (20s), indicating AF.

Formation and characterization of emulsions consisting of dense carbon dioxide and water: Ultrasound

In this work, we studied ultrasound formation of surfactant-free emulsions consisting of water and dense carbon dioxide (CO2). Emulsions with limited kinetic stability were formed after approximately 2min of pulsed ultrasound at 20kHz and above a critical power density of at least 0.05Wcm−3. Emulsion stability and formation were studied using a variety of techniques. In situ microscopy using a high-pressure microfluidic reactor indicated that the water/CO2 emulsion consisted of finer droplets of about 5μm compared to the CO2/water emulsion which consisted of droplets with average diameters of about 12μm. A partially miscible tracer technique was used to measure the dispersed phase content of the two emulsions to be about 4vol% and up to 9vol% for the CO2/water and water/CO2 emulsions, respectively. Engineering analysis and complementary experiments indicated that the water/CO2 emulsions formed via a two-step mechanism consisting of surface wave break-up to form a coarse emulsion followed by cavitation to form a fine emulsion. We use KI oxidation as a probe reaction to examine ultrasound-induced chemistry in the dense CO2/water system, finding that KI oxidation was suppressed by the presence of a high pressure CO2 phase. Through the combination of formation, stability, and KI oxidation experiments and analyses, we suggest that the dense CO2 cushioned cavitation bubble collapse, damping ultrasound chemical effects while permitting physical effects such as emulsification. Engineering analysis suggests energy efficient scale-up might be achieved in a carefully designed flow reactor.

Nighttime instabilities of neurophysiological, cardiovascular, and respiratory activity: integrative modeling and preliminary results

Unstable (cyclical alternating pattern, or CAP) sleep is associated with surges of sympathetic nervous system activity, increased blood pressure and vasoconstriction, heightened baroreflex sensitivity, and unstable heart rhythm and breathing. In susceptible persons, CAP sleep provokes clinically significant events, including hypertensive crises, sleep-disordered breathing, and cardiac arrhythmias. Here we explore the neurophysiology of CAP sleep and its impact on cardiovascular and respiratory functions. We show that: (i) an increase in neurophysiological recovery rate can explain the emergence of slow, self-sustained, hypersynchronized A1 CAP-sleep pattern and its transition to the faster A2-A3 CAP-sleep patterns; (ii) in a two-dimensional, continuous model of cardiac tissue with heterogeneous action potential duration (APD) distribution, heart rate accelerations during CAP sleep may encounter incompletely recovered electrical excitability in cell clusters with longer APD. If the interaction between short cycle length and incomplete, spatially heterogeneous repolarization persists over multiple cycles, irregularities and asymmetry of depolarization front may accumulate and ultimately lead to a conduction block, retrograde conduction, breakup of activation waves, reentrant activity, and arrhythmias; and (iii) these modeling results are consistent with the nighttime data obtained from patients with structural heart disease (N=13) that show clusters of atrial and ventricular premature beats occurring during the periods of unstable heart rhythm and respiration that accompany CAP sleep. In these patients, CAP sleep is also accompanied by delayed adaptation of QT intervals and T-wave alternans.

Spiral wave classification using normalized compression distance: Towards atrial tissue spatiotemporal electrophysiological behavior characterization.

Analysis of electrical activation patterns such as re-entries during atrial fibrillation (Afib) is crucial in understanding arrhythmic mechanisms and assessment of diagnostic measures. Spiral waves are a phenomena that provide intuitive basis for re-entries occurring in cardiac tissue. Distinct spiral wave behaviors such as stable spiral waves, meandering spiral waves, and spiral wave break-up may have distinct electrogram manifestations on a mapping catheter. Hence, it is desirable to have an automated classification of spiral wave behavior based on catheter recordings for a qualitative characterization of spatiotemporal electrophysiological activity on atrial tissue. In this study, we propose a method for classification of spatiotemporal characteristics of simulated atrial activation patterns in terms of distinct spiral wave behaviors during Afib using two different techniques: normalized compressed distance (NCD) and normalized FFT (NFFTD). We use a phenomenological model for cardiac electrical propagation to produce various simulated spiral wave behaviors on a 2D grid and labeled them as stable, meandering, or breakup. By mimicking commonly used catheter types, a star shaped and a circular shaped both of which do the local readings from atrial wall, monopolar and bipolar intracardiac electrograms are simulated. Virtual catheters are positioned at different locations on the grid. The classification performance for different catheter locations, types and for monopolar or bipolar readings were also compared. We observed that the performance for each case differed slightly. However, we found that NCD performance is superior to NFFTD. Through the simulation study, we showed the theoretical validation of the proposed method. Our findings suggest that a qualitative wavefront activation pattern can be assessed during Afib without the need for highly invasive mapping techniques such as multisite simultaneous electrogram recordings.