Local Front Research Articles

Characterizing binary droplet collisions of power‐law fluids

AbstractThis study focuses on the dynamics of two equal‐sized droplets of non‐Newtonian liquids with simulations using the volume of fluid method and the local front reconstruction method. The non‐Newtonian behavior is implement via a power‐law model. The droplet interactions are performed for Weber numbers ranging from 20 to 300 and impact parameters from 0 to 0.6. Both methods produce similar results at low Weber numbers, while the disintegration of the droplets at high Weber numbers occurs via different mechanisms. Our results demonstrate that the boundaries of the collision maps are highly dependent on the power‐law index. Additionally, the diameter of the ring for head‐on collisions is increased with increasing Weber number and decreasing power‐law index, while the critical ligament length in off‐center collisions increases with Weber number and power‐law index.

A hierarchical clustering algorithm for addressing multi-modal multi-objective optimization problems

Many evolutionary multi-modal multi-objective algorithms (MMEAs) have been proposed to solve multi-modal multi-objective optimization problems (MMOPs). Unfortunately, the environmental selection process causes many algorithms to place too much emphasis on solution variety in the decision space, which leads to solutions with low convergence quality. As a result, not only are all local Pareto fronts reversed, but objective values are also far lower than the global Pareto Fronts. To tackle these tasks, this paper proposes a hierarchical clustering-based MMOEA_DC_HR model that uses decision space clustering methods to group neighborhood solutions into several local clusters, preserving local Pareto Sets. And secondary clustering is performed in the objective space to select temporary populations from these local clusters to maintain the diversity of the objective space. Additionally, a hierarchical ranking method is introduced to update the convergence archive aiding in maintaining the convergence of the algorithm and controlling the quality of the Pareto Front. The test results show that this novel algorithm exhibits competitive performance in solving selected benchmark problems when compared to other cutting-edge MMEAs.

Dual-space distribution metric-based evolutionary algorithm for multimodal multi-objective optimization

Multimodal multi-objective optimization problems (MMOPs) are characterized by having multiple global or local Pareto solution sets. In most of multimodal multi-objective evolutionary algorithms, the distribution of population in objective space and decision space cannot be taken into account, simultaneously. In this paper, an innovative evolutionary algorithm based on dual-space distribution metric for multimodal multi-objective optimization (DsDMEA) is designed to solve this problem. Specifically, the two enhanced performance metrics are coupled together as a single dual-space distribution metric (DsDM) serving as the criterion for environmental selection. DsDMEA explores solutions on Pareto front and Pareto solutions sets that are not associated with the reference point, which show limited contributions to the distribution in dual spaces. Then DsDMEA removes any bi-noncontributing solutions using DsDM during environmental selection until the population size is met. This achieves a balance between the distribution of solutions and convergence in decision space. At the same time, this paper introduces a novel fitness computation method, enabling the precise localization of local Pareto fronts within the population. Finally, eight state-of-the-art multimodal multi-objective evolutionary algorithms are adopted to make a comparison on two types of benchmark to verify the performance of the DsDMEA. The experimental results demonstrated the DsDMEA effectiveness in solving MMOPs with local problems and traditional MMOPs.

A coupled local front reconstruction and immersed boundary method for simulating 3D multiphase flows with contact line dynamics in complex geometries

Multi-phase flows in the presence of complex solid geometries are encountered widely throughout industrial processes to intensify mass and heat transfer processes. The efficiency of these processes relies largely on the predominant fluid dynamics regime inside the reaction vessel (e.g. trickle bed, bubble column reactor). The prevailing flow structure is influenced by many factors including the nature of the fluid-solid interactions (i.e. wetting or non-wetting). Such flows are often studied using front-capturing techniques to capture the fluid-fluid interface in combination with an auxiliary model to account for fluid-solid interactions. However, these front-capturing methods have difficulties in accurately representing the interface. Therefore, we adopted a front-tracking method: the Local Front Reconstruction Method (LFRM). In this study, LFRM is coupled with the Immersed Boundary method to incorporate the no-slip boundary condition at the solid surface. The model performance is assessed using droplet spreading simulations, where the equilibrium droplet shape (i.e. radius, height, and outline), the interfacial pressure difference, and the surface tension force are compared to analytical solutions and literature data. The results show an excellent match with the analytical solutions, and additionally superior performance to state-of-the-art volume tracking models.

Numerical simulation of jet break-up in the second-wind induced regime using the local front reconstruction method

In the second wind-induced regime, the jet deformations are influenced by aerodynamic instabilities acting on the jet surface. In addition, velocity relaxation in the liquid is an important mechanism with a strong influence on the violent break-up of laminar jets (i.e., the bursting). The exact interplay between the aerodynamic forces and the velocity profile relaxation is insufficiently described in the literature. Thus, we investigate numerically cylindrical liquid jets with fully developed and uniform velocity inlet profiles for different liquid and gas properties to elucidate the physical mechanisms governing the bursting of the jet. For this study, the gas-liquid interface is tracked using a front tracking technique: the Local Front Reconstruction Method (LFRM). In contrast with traditional front tracking techniques, LFRM allows for complex topological changes (merging and break-up) while keeping a sharp representation of the interface. The comparison of the obtained results with literature suggests that LFRM is a suitable technique for capturing the complex morphological deformations of a bursting jet. Additionally, we analyzed the influence of air and liquid properties on the jet deformations, which evidenced that velocity profile relaxation plays an important role in the complex process of break-up of the jet, that in combination with the destabilizing effect of the aerodynamic forces lead to the bursting of the jet.

Numerical analysis of laminar velocity-forced premixed slit flames using modal decomposition techniques

The relation between Proper Orthogonal Decomposition (POD), Dynamic Mode Decomposition (DMD) and Flame Transfer Functions (FTF) is explored to gain further insight into the dynamics of two-dimensional laminar slit flames externally forced by velocity perturbations. The application of POD to the heat release rate fields suggests that the resultant modes can be split into two groups: the ones that are related to the displacement of the reactive sheet in the normal direction with regards to the flame front, and the ones that contain the local flame front distortions. The latter modes show preferential frequencies associated to the phase values of π, 2π and 3π of the FTFs, which can be related to the maximum gain value depending on the case. Furthermore, the results of the modal analysis seem to support that the flame tip dynamics can be conceptually modelled as a set of standing waves whose joint response can reconstruct a propagation in the normal flame front direction, generating also the temporal fluctuations of the spatially-integrated heat release in the domain. The DMD analysis shows the existence of an interaction between the flame and the flow, and illustrates the fundamental role played by the velocity perturbations at the base for the motion of the reactive sheet. Thus, the analysis shows how data-based decomposition methods can be used to identify complex physical phenomena contained in the FTF graphs with different levels of detail, and extend the modal analysis to the physical space.Novelty and significance statementThis paper proves the potential of modal decomposition techniques like POD and DMD to infer the underlying physics of canonical flames and their relation to the FTF, validating also the hypotheses and methodology of other reduced-order models in the literature. A canonical configuration featuring a two-dimensional slit flame has been selected to analyse the flame dynamics using these methods. Hence, this work aims to set the foundations to elaborate data-driven reduced-order models based on modal decomposition techniques to support the analysis and the study of flame dynamics.

Numerical investigation of non-Newtonian droplet collisions: Comparison of volume of fluid and the local front reconstruction method with experimental data

Droplet-droplet collisions of non-Newtonian fluids are often encountered in industrial applications such as spray drying, fluid catalytic cracking, coating and granulation. However, there has been limited focus on a comprehensive analysis of the dynamics of these non-Newtonian binary droplet collisions. In this work, the non-Newtonian binary droplet collisions of 500 ppm xanthan gum solutions are simulated using the Volume of Fluid method and the Local Front Reconstruction Method to determine the applicability of these methods for the simulations of binary non-Newtonian droplet collisions. After verification, the simulations are compared to experimental data from literature. The outcomes for off-center collisions in the simulations resemble the experimental observations, including the oscillation of the ligament. For head-on collisions, the initial interactions and collision dynamics can be predicted with both methods at low Weber numbers, while LFRM shows improved performance at higher Weber numbers. Further, the use of an effective viscosity for the simplified representation of the droplet collision has been proven unsuccessful due to the absence of a universal effective viscosity for all situations.

High-frequency hydrogen combustion dynamics driven by local flame displacement and multidimensional thermoacoustic interactions

Knowledge of the underlying physical mechanisms responsible for the triggering of high-frequency transverse combustion dynamics is of fundamental importance in the development of heavy-duty gas turbine combustors, aircraft engine afterburners, and bipropellant liquid rocket engines. Detailed information about three-dimensional thermoacoustic interactions and local flame dynamics, however, remains largely unknown and unanticipated, mainly because high-amplitude transverse mode instabilities are challenging to excite and detect in well-controlled sub-scale laboratory environments. To overcome this impasse, here we exploit a spatially tailored rectangular injector assembly consisting of ten equidistant horizontal slit nozzles to eliminate the complications of out-of-plane flame dynamics characterization. A total of 56 datasets of self-induced instabilities were acquired over a wide range of operating conditions to understand spatiotemporal phase dynamics and important mode shapes, in conjunction with 2D Rayleigh angle reconstruction and phase-resolved OH PLIF-based local flame front identification. Experimentally, we show that high-frequency transverse instabilities are excited only under high temperature and high thermal power conditions, manifested as non-evanescent pressure fluctuations at 6.50 kHz strongly coupled to the second-order tangential mode of the rectangular combustion chamber. Two vertically-oriented pressure nodal planes and the characteristic phase transition perpendicular to the horizontal slit injector direction are accurately measured and reconfirmed by Helmholtz simulations in terms of their interpositions and spatial orientation. Remarkably, the periodic formation of co-propagating coherent structures and concomitant local flame displacement/pinch-off are revealed to play an important role in driving the high-frequency hydrogen combustion dynamics.

Solid Waste Generation and Management Practices at Sherubtse College

The enduring challenge of waste management poses a significant and ongoing global concern, demanding urgent and concerted efforts for sustainable solutions. Waste-related issues, ranging from inadequate disposal to the overwhelming volume of single use plastics, have consistently plagued communities worldwide. In light of these challenges, this study seeks to contribute valuable insights toward the development of effective strategies on both local and global fronts. The study sampled student hostels and staff quarters to understand the waste generation and management practices at Sherubtse College. Dry wastes were collected over a period of 9 weeks. Through the segregation and quantification carried out weekly, it is known that, about 0.07 kilogram(kg) of dry waste was generated by each student and 0.34 kg per staff household in a day. Among the dry waste collected, papers weighed the most. A survey was also conducted on wet waste generated on campus. It was found that per day about 0.64 kg of wet waste was generated by each staff household and 1.41 kg per hostel. In our quest to minimize waste, the analysis of quantified waste serves as a foundational starting point, providing a crucial understanding of production patterns and guiding targeted efforts toward effective waste reduction.

An improved differential evolution algorithm for multi-modal multi-objective optimization.

Multi-modal multi-objective problems (MMOPs) have gained much attention during the last decade. These problems have two or more global or local Pareto optimal sets (PSs), some of which map to the same Pareto front (PF). This article presents a new affinity propagation clustering (APC) method based on the Multi-modal multi-objective differential evolution (MMODE) algorithm, called MMODE_AP, for the suit of CEC'2020 benchmark functions. First, two adaptive mutation strategies are adopted to balance exploration and exploitation and improve the diversity in the evolution process. Then, the affinity propagation clustering method is adopted to define the crowding degree in decision space (DS) and objective space (OS). Meanwhile, the non-dominated sorting scheme incorporates a particular crowding distance to truncate the population during the environmental selection process, which can obtain well-distributed solutions in both DS and OS. Moreover, the local PF membership of the solution is defined, and a predefined parameter is introduced to maintain of the local PSs and solutions around the global PS. Finally, the proposed algorithm is implemented on the suit of CEC'2020 benchmark functions for comparison with some MMODE algorithms. According to the experimental study results, the proposed MMODE_AP algorithm has about 20 better performance results on benchmark functions compared to its competitors in terms of reciprocal of Pareto sets proximity (rPSP), inverted generational distances (IGD) in the decision (IGDX) and objective (IGDF). The proposed algorithm can efficiently achieve the two goals, i.e., the convergence to the true local and global Pareto fronts along with better distributed Pareto solutions on the Pareto fronts.

Quantifying Changes in the Florida Synoptic-Scale Sea-Breeze Regime Climatology

Abstract Florida’s summertime precipitation patterns are in part influenced by convergence between the synoptic-scale wind and local sea-breeze fronts that form along the east and west coasts of the peninsula. While the National Weather Service previously defined nine sea-breeze regimes resulting from variations in the synoptic-scale vector wind field near Tampa, Florida, these regimes were developed using a shorter 18-yr period and examined primarily for the purposes of short-term weather prediction. This study employs reanalysis data to develop a full 30-yr climatology of the Florida sea-breeze regime distribution and analyze the composite mean atmospheric conditions associated with each regime. Further, given that 1) the synoptic-scale wind primarily varies as a result of movement in the western ridge of the North Atlantic subtropical high (NASH), and 2) previous studies suggest long-term shifts in the mean position of the NASH western ridge, this study also examines variability and trends in the sea-breeze regime distribution and its relationship to rainy-day frequency over a longer 60-yr period. Results indicate that synoptic-scale flow from the west through southwest, which enhances precipitation probabilities along the eastern half of the peninsula, has increased in frequency, while flow from the east through northeast has decreased in frequency. These changes in the sea-breeze regime distribution may be partially responsible for increases in rainy-day frequency during June–August over northeastern Florida, though results suggest that other factors likely contribute to interannual variability in precipitation across the southern peninsula.

Numerical simulation of jet break‐up using the local front reconstruction method

AbstractPrimary break‐up of liquid jets is often encountered in industrial processes and is scientifically challenging due to its complexity. An accurate description of the break‐up length and droplet sizes is critical for controlling the jet dynamics and hence the process performance. Despite the extensive research performed on jet break‐up, the existing correlations are not universally applicable to all encountered flow conditions. In this article, we perform Direct Numerical Simulation of a cylindrical liquid jet using the Local Front Reconstruction Method (LFRM) to track the liquid‐gas interface. Experiments are also carried out to validate the simulation results in the same range of Reynolds and Weber numbers. The LFRM method is able to accurately reproduce the experimental break‐up lengths and droplet diameters. The surface waves propagating along the jet are compared with the dominant wavelengths reported in literature. It can be concluded that LFRM can accurately describe the dynamics of laminar jets.

Morphology and turbulent burning velocity of n-decane/air expanding flames at constant turbulent Reynolds numbers

In this work we experimentally investigated the propagation and the turbulent burning velocity of n-decane/air turbulent expanding flames at 423 K and 0.5-3.0 atm, with constant turbulent Reynold number, ReT,flow = (urmsLI)/ν, ranging from 174 to 4712, using a medium-scale, fan-stirred combustion chamber, where urms and LI are respectively the turbulence intensity and the integral length scale, and ν is the kinematic viscosity of a fresh mixture. It was found that the n-decane/air turbulent expanding flame is self-similar, and the normalized turbulent flame propagation speed scales with the turbulent flame Reynold number, ReT,flame = (urms/SL)(〈r〉/δL), to the one-half power for mixtures characterized by non-unity Lewis numbers, where the mean flame radius (〈r〉) is the length scale, and the thermal diffusivity (α = SLδL) is the transport property. The turbulent burning velocity (ST,c=0.5) at the mean progress variable (〈c〉) of 0.5 decreases with the pressure at a constant ReT,flow, following the similar pressure dependence of the laminar burning velocity (SL). The ST,c=0.5/SL of the fuel-rich n-decane/air flame (ϕ = 1.4) is twice larger than that of the fuel-lean mixture (ϕ = 0.8), which would be attributed to the promotion of local burning rates by coupling between the differential diffusion and the turbulent flame stretch on the local flame fronts. In addition, five useful modified correlations for the turbulent burning velocity with the experimental Lewis number (LeBM) consideration were obtained based on the present experimental data of n-decane/air turbulent expanding flames. Particularly, the successful scaling of the modified correlation based on Damköhler's second hypothesis, ST,c=0.5/SL = 1 + 0.115(ReT,flowLeBM−2)0.5, suggesting that the ST,c=0.5/SL is inversely proportional to the LeBM. The importance of using experimental determined values of the Lewis number in the scaling of turbulent burning velocity with the differential diffusion consideration should be emphasized.

Thermodiffusively unstable laminar hydrogen flame in a sufficiently large 3D computational domain – Part I: Characteristic patterns

Thermodiffusive instabilities can have a leading order effect on flame propagation for lean premixed hydrogen flames. Many simulation studies have been performed to study this effect, but almost exclusively in two-dimensional (2D) or domain sizes too small to support the characteristic large-scale features of the instability. The main purpose of this study is to quantify the differences of 3D and 2D flames using simulations on sufficiently large domains. To this end, direct numerical simulations (DNS) of thermodiffusively unstable laminar premixed hydrogen flames stabilized in 3D domains were performed. The effects of confinement on the flame dynamics are rigorously investigated by varying the domain size. The flame burning velocity shows a strong dependence on the domain size when the lateral domain width is less than 50 laminar flame thicknesses. The characteristic patterns of the thermodiffusively unstable flame are analyzed in detail, including the instantaneous flame structure, global burning velocity, flame surface area, stretch factor, curvature distribution, and the cell size. The effects of the computational setup (2D vs. 3D) on the local flame front curvature and the distributions of the thermo-chemical quantities are quantified through a conditional analysis. The formation and destruction mechanisms of the distinct cellular structures observed in the 3D domain are analyzed focusing on the interactions between the flame dynamics and the flow field, and the contributions of the production of flame surface density, kinematic restoration, and curvature dissipation are quantified. Compared with the corresponding 2D simulation, the flame surface area in the cut plane of the 3D configuration is similar, yet the burning velocity and the stretch factor are increased. The reason for this is the difference in curvature statistics in 2D and 3D. In 3D, larger extreme curvature values are obtained, leading to quantitatively different distributions of the thermo-chemical variables. For example, the peak H radical concentration in the 3D simulation is about twice higher than in the 2D simulation.Novelty and significance statementThe novelty of the present work includes the following aspects:(i) First large-scale 3D DNS of laminar lean premixed hydrogen flame on domain large enough to obtain domain-independent results.(ii) First quantitative assessment of characteristic patterns of 3D thermodiffusively unstable premixed hydrogen flames.(iii) First quantitative assessment of differences between 2D and 3D thermodiffusively unstable premixed hydrogen flames for domain-independent results.

Numerical simulation of binary droplet collisions using a Front Tracking interface technique

Droplet-droplet interactions of highly viscous liquids or suspensions are relevant in a broad range of industrial applications, such as spray drying, fuel injection or, coating and granulation. The efficiency of these processes is heavily determined by the surface area and volume of the droplets. To operate these processes efficiently, it is critical to accurately describe the physical mechanisms dominating the collision. Nonetheless, a complete description of the forces governing the collision is still missing, particularly when the liquids have a high viscosity. Front tracking techniques represent a promising alternative for studying droplet-droplet interactions as they ensure a sharper representation of the liquid-gas interface. In this work, the Local Front Reconstruction Method (LFRM) is the front tracking technique chosen as it allows merging and break-up. The validation of this method is extended for different Weber numbers, impact parameters, and liquid properties by determining the capabilities of LFRM to reproduce the collision of glycerol solution droplets. The simulation results are validated with dedicated experiments performed at the same Weber and impact parameter conditions. In the majority of the studied collisions, LFRM shows a good correspondence with experiments and literature, which proves the ability of LFRM to capture droplet collisions under the studied conditions.

Rent Arrears, Food Shortages and Evacuees: How War Enters the Worcester Home in Two World Wars

ABSTRACT The strong military traditions of Worcester may mean the city’s engagement in two world wars is often thought about in terms of the soldiers or even the ammunition produced at Blackpole Munitions Works. The ways in which both wars impacted the more mundane lives of the majority of women who were housewives have received less attention. As housewives, daughters, sisters or domestic servants, women undertook the lion’s share of the domestic and emotional labours needed to maintain homes, communities and neighbourhoods. This was played out at a local level, shaped by the geographical, economic and cultural specificity of not only regions but towns and cities. There were as many different home fronts as there were battle fronts; thus, Worcester residents experienced the privations and problems of twentieth-century large-scale international warfare, through their local home front. This contextualized case study of Worcester explores the financial challenges housewives faced, their problems with food provisioning and the care of evacuees to argue that both wars entered the home in a multitude of ways. It provides evidence of how, the boundary between public and private spheres was blurred, as in wartime the state interfered in the domestic life to an unprecedented degree.

Flame propagation patterns and local flame features of an annular combustor with multiple centrally staged swirling burners

In this paper, the transient ignition process of an annular combustor with 16 centrally staged swirling burners is experimentally investigated to study the mechanism of burner–burner flame propagation. The flame propagation patterns are studied by high-speed imaging. Three typical patterns of the burner–burner flame propagation are identified: the kindled-swirling pattern, entrained-swirling pattern, and sweeping pattern. The patterns are featured with different flame paths of motion. For fixed flow rates, the paths of motion are mainly determined by the overall equivalence ratio Φ. Furthermore, during the burner–burner flame propagation, the effect of the flow field on the local flame fronts is analyzed by Mie scattering and particle image velocimetry (PIV) methods. The PIV results show that the flame paths of motion are greatly influenced by the flow structure of the annular combustor. The optical diagnosis of the flame–flow interaction provides new insights into the ignition dynamics of the centrally staged annular combustor.

Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion

Direct numerical simulations of non-premixed fuel-rich methane–oxygen flames at 20 bar are conducted to investigate the turbulent mixing burning of gaseous propellants in rocket engines. The reacting flow is simulated by using an EBI-DNS solver within an OpenFOAM frame. The transport of species is resolved with finite-rate chemistry by using a complex skeletal mechanism that entails 21 species. Two different flames at low and high Reynolds numbers are considered to study the sensitivity of the flame dynamics to turbulence. Regime markers are used to measure the probability of the flow to burn in premixed and non-premixed conditions at different regions. The local heat release statistics are studied in order to understand the drivers in the development of the turbulent diffusion flame. Despite the eminent non-premixed configuration, a significant amount of combustion takes place in premixed conditions. Premixed combustion is viable in both lean and fuel-rich regions, relatively far from the stoichiometric line. It has been found that a growing turbulent kinetic energy is detrimental to combustion in fuel-rich premixed conditions. This is motivated by the disruption of the local premixed flame front, which promotes fuel transport into the diffusion flame. In addition, at downstream positions, higher turbulence enables the advection of methane into the lean core of the flame, enhancing the burning rates in these regions. Therefore, the primary effect of turbulence is to increase the fraction of propellants burnt in oxygen-rich and near-stoichiometric conditions. Consequently, the mixture fraction of the products shifts towards lean conditions, influencing combustion completion at downstream positions.

An enhanced bacterial colony optimization with dynamic multi‐leader co‐evolution for multiobjective optimization problems

AbstractThe information transfer mechanism within the population is an essential factor for population‐based multiobjective optimization algorithms. An efficient leader selection strategy can effectively help the population to approach the true Pareto front. However, traditional population‐based multiobjective optimization algorithms are restricted to a single global leader and cannot transfer information efficiently. To overcome those limitations, in this paper, a multiobjective bacterial colony optimization with dynamic multi‐leader co‐evolution (MBCO/DML) is proposed, and a novel information transfer mechanism is developed within the group for adaptive evolution. Specifically, to enhance convergence and diversity, a multi‐leaders learning mechanism is designed based on a dynamically evolving elite archive via direction‐based hierarchical clustering. Finally, adaptive bacterial elimination is proposed to enable bacteria to escape from the local Pareto front according to convergence status. The results of numerical experiments show the superiority of the proposed algorithm in comparison with related population‐based multiobjective optimization algorithms on 24 frequently used benchmarks. This paper demonstrates the effectiveness of our dynamic leader selection in information transfer for improving both convergence and diversity to solve multiobjective optimization problems, which plays a significant role in information transfer of population evolution. Furthermore, we confirm the validity of the co‐evolution framework to the bacterial‐based optimization algorithm, greatly enhancing the searching capability for bacterial colony.

The role of thermokarst evolution in debris flow initiation (Hüttekar Rock Glacier, Austrian Alps)

Abstract. A rapid sequence of cascading events involving thermokarst lake outburst, local rock glacier front failure, debris flow development, and river blockage hit Radurschl Valley (Ötztal Alps, Tyrol) on 13 August 2019. Compounding effects from permafrost degradation and drainage network development within the rock glacier initiated the complex process chain. The debris flow dammed the main river of the valley, impounding a water volume of 120 000 m3 that was partly drained by excavation to prevent a potentially catastrophic outburst flood. We present a systematic analysis of destabilizing factors to deduce the failure mechanism. The identification and evaluation of individual factors reveals a critical combination of topographical and sedimentological disposition, climate, and weather patterns driving the evolution of a thermokarst drainage network. Progressively changing groundwater flow and storage patterns within the frozen sediment accumulation governed the slope stability of the rock glacier front. Our results demonstrate the hazard potential of active rock glaciers due to their large amount of mobilizable sediment, dynamically changing internal structure, thermokarst lake development, and substantial water flow along a rapidly evolving channel network.