Large-scale Laboratory Experiments Research Articles

Wave Breaking Eddies And Transient Rip Current Dynamics In Large-Scale Wave Basin Experiments

Wave Breaking Eddies And Transient Rip Current Dynamics In Large-Scale Wave Basin Experiments

Predicting the vertical density structure of oceanic gravity current intrusions

Understanding the dynamics and structures in the deep ocean is one of the remaining challenges in oceanography and climate sciences. We present results from large-scale laboratory experiments of rotating down-slope gravity currents intruding into a two-layer stratified ambient, performed in the largest rotating tank in the world, the Coriolis Rotating Platform in Grenoble. By means of velocity and density measurements, we show that no mixing occurs once the current has detached from the boundary. The shape of the vertical density profile in the stratified receiving ambient enables to identify two distinct regimes: the first issued by laminar transport through Ekman dynamics, the second by turbulent transport due to intermittent dense water cascading. Vertical density gradients reveal a piece-wise linear dependence on the density anomaly for the turbulent transport, suggesting an advection-diffusion process. For the turbulent regime, the scale height is deduced and an analytical model based on the critical Froude number is proposed to predict its value. Results show that the total thickness of the intruding current is on average 2.5 times the scale height. For laminar intrusions the scale height diverges whereas the thickness of the intrusion is a few times the Ekman layer thickness. Comparing the intrusion scale height with its measured vertical extension has led to a criteria to distinguish between laminar and turbulent regimes, which is corroborated by two additional independent criteria, one based on the sign of the local vorticity and the other based on the local maxima of the vertical density gradient. The model allows us to connect laboratory experiments to deep sea observations, gravity currents and Meddies and emphasizes the importance of laboratory experiments in understanding climate dynamics.

Observations of wave run-up affected by dune scarp during storm conditions: a two dimensional large-scaled movable bed experiment

Artificial dunes serve as essential nature-based defenses against the increasing threats posed by climate change and rising sea levels along coastal regions. However, these man-made dunes are particularly susceptible to erosion during severe storm events, necessitating careful consideration of their design for effective coastal protection. Among the myriad factors influencing artificial dune design, wave run-up stands out as a paramount concern. Not only is wave run-up crucial in assessing the extent of coastal flooding, but it also plays a significant role in shaping shoreline dynamics. During intense storm events, wave run-up amplification leads to substantial erosion of sand dunes, forming dune scarps that resemble cliffs. To address these challenges, we conducted a series of innovative two-dimensional large-scale laboratory experiments using movable beds. These experiments aimed to provide a quantitative understanding of wave run-up characteristics on dune scarps. Additionally, our study explored the feasibility of using existing empirical formulas to predict the 2% exceedance of wave run-up (referred to as R2%) in such scenarios. Our results revealed a consistent trend in R2% values, irrespective of variations in the surf similarity parameter when wave run-up was influenced by a dune scarp. Notably, our findings recommend the adoption of the Stockdon empirical formula, incorporating beach slope from the still water level to the dune scarp toe, as an effective method for predicting R2% during highly erosive conditions. This approach can significantly enhance the design and functionality of artificial dunes, bolstering their capacity to safeguard coastal areas from the impacts of severe storms and erosion, thus contributing to resilient coastal ecosystems and sustainable coastal management.

Field observations of wave-averaged suspended sediment concentrations in the inner surf zone with varying storm conditions

During extreme conditions the transport of the wave-averaged suspended sediment concentrations in the inner surf zone affects dune erosion. Although large-scale laboratory experiments have provided insight what drives these sediment concentrations, corresponding field data is lacking. To fill this gap novel field observations of suspended sediment concentrations are compared to drivers known from literature that govern sediment suspension during storm conditions. A total of 128 time intervals of 20 min are analysed, spread over 10 different high water events with different hydrodynamic conditions. For each time interval, the wave-averaged (i.e. 20-min mean) suspended sediment concentration is computed and compared to three suspension drivers. The studied drivers are (1) bed shear due to near bed velocities that originate from mean currents in combination with wave-induced orbital flow, (2) the horizontal pressure gradients under steep wave fronts that increase the forces on the bed material, and (3) bore-induced turbulence that is generated at the free surface and reaches the bed. The derived bore-induced turbulence generates the greatest correlation with the mean suspended sediment concentrations (r = 0.74, p = 4.47E-23). Samples that deviate from this correlation correspond to time intervals with lower values of derived bore turbulence, less wave energy saturation in the inner surf zone, and stronger mean currents. The correlation with the mean suspended sediment concentrations increases when the shear stress originating from mean currents is used for these time intervals (r = 0.83, p = 1.63E-33). Overall, for time intervals during which more energetic conditions persist and the wave energy is saturated in the nearshore, bore turbulence becomes the dominant mechanism in stirring up sediment. The outcome of this study suggests that, based on the events analysed, dune erosion models may achieve more accurate results if computations of suspended sediment concentrations include a bore-induced turbulence term, or if already included, properly address the relative importance of bore-induced turbulence when compared to bed shearing.

Signature size and individual preferences

In this digital economy, customers' handwriting, such as signatures and related characteristics, can be easily collected and quantitatively analyzed. From the perspective of decision-making, obtaining information from signature characteristics is an important data-driven business leverage. In this regard, can we infer individual preferences from signatures? Thus, through a large-scale laboratory experiment, this study measured the participants’ risk and time preferences and collected their signature information in order to determine the influence of behavioral preferences on their signatures. Based on the empirical results, the higher the risk and ambiguity aversion of the participants, the smaller were their signature sizes. Moreover, the greater their level of patience, the more likely their signatures showed a trend of increasing size. Overall, this study fills a research gap in signature-related behavior by highlighting the application of text mining in digital handwriting, especially in broad business settings such as the insurance industry.

Numerical Modelling and Predicting Performance of Geogrid-Reinforced Low-Volume Unpaved Roads over Soft Subgrades

AbstractPavement performance is usually predicted by large-scale laboratory experiments, expensive field tests and/or comparatively cheaper numerical modelling alternative. In this study, a finite element limiting strain model has been developed to investigate the strain response of both unreinforced and geogrid-reinforced pavements on unpaved roads where the geogrid is placed at the bottom of the unbound granular base layer. A two-dimensional (2D) axisymmetric finite element model (FEM) is used to analyse the behaviour of both unreinforced and geogrid-reinforced granular base. The critical pavement responses (vertical surface deformation, compressive strain and compressive stress at the top of subgrade, etc.) are simulated numerically using ABAQUS. These critical responses are used to develop the pavement performance models (strain limiting models) and to predict long-term service life of pavement or the reduction of thickness of granular base for equivalent service life or a combination of both. The parametric results are then used to develop design charts to aid practitioners to use directly in designs. The numerical model is verified using published literature-based information and found to be reasonable. The results show that the traffic benefit ratio (TBR) of 3.1 at a 20 mm rut depth can be achieved for a thin granular base built over soft subgrade using a medium stiff geogrid.

Calibration of the root water uptake spatial distribution of a young Melaleuca styphelioides, an Australian-native plant, by means of a large-scale apparatus experiment

The stability of slopes is greatly influenced by seasonal variations in pore water pressures (pwp) induced by rainfall infiltration and evapotranspiration processes. Despite that, the prediction of the hydrological effects of long-stem planting is often simplified or neglected because it is challenging to address. Its computation requires a proper definition of the plant root water uptake spatial distribution, which depends, in turn, on geometry and spatial root density. A well-suited case study in this field of application has been provided by a soil-filled embankment, close to an important traffic artery in Newcastle (Australia), which experienced shallow instability. The implementation of long-stem planting has been suggested as a remediation intervention. Based on this, an experimental study focusing on the effects of plant roots on the distribution of pwp in the site soil has been performed by means of a large-scale laboratory experiment on a 2-year-old native plant. Suction measurements were recorded within the vegetated soil mass under controlled boundary conditions and used to calibrate two different root spatial distributions in a seepage simulation. One is based on a flexible RWU spatial distribution function, and the other, specific for the plant RWU pattern, is simpler in its formulation and requires the definition of a lower number of parameters. A comparison between their performances in reproducing pwp distribution suggests that the second one is a better alternative. The methodological approach adopted has proven to be suitable for representing the hydraulic behaviour of a vegetated hillslope, to be eventually implemented in a proper stability assessment problem.

Prediction of the Form of a Hardened Metal Workpiece during the Straightening Process

In industry, metal workpieces are often heat-treated to improve their mechanical properties, which leads to unwanted deformations and changes in their geometry. Due to their high hardness (60 HRC or more), conventional bending and rolling straightening approaches are not effective, as a failure of the material occurs. The aim of the research was to develop a predictive model that predicts the change in the form of a hardened workpiece as a function of the arbitrary set of strikes that deform the surface plastically. A large-scale laboratory experiment was carried out in which a database of 3063 samples was prepared, based on the controlled application of plastic deformations on the surface of the workpiece and high-resolution capture of the workpiece geometry. The different types of input data, describing, on the one hand, the performed plastic surface deformations on the workpieces, and on the other hand the point cloud of the workpiece geometry, were combined appropriately into a form that is a suitable input for a U-Net convolutional neural network. The U-Net model’s performance was investigated using three statistical indicators. These indicators were: relative absolute error (RAE), root mean squared error (RMSE), and relative squared error (RSE). The results showed that the model had excellent prediction performance, with the mean values of RMSE less than 0.013, RAE less than 0.05, and RSE less than 0.004 on test data. Based on the results, we concluded that the proposed model could be a useful tool for designing an optimal straightening strategy for high-hardness metal workpieces. Our results will open the doors to implementing digital sustainability techniques, since more efficient handling will result in fewer subsequent heat treatments and shorter handling times. An important goal of digital sustainability is to reduce electricity consumption in production, which this approach will certainly do.

Development, calibration and validation of a phase-averaged model for cross-shore sediment transport and morphodynamics on a barred beach

Simulating cross-shore sediment transport and associated sandbar migration is still a challenging task for phase-averaged coastal morphological models. Numerical studies have mostly relied on beach morphology prediction for calibration and validation, without examining in much detail the underlying hydrodynamics, sediment concentrations and transport rates. This paper reports on a new three-dimensional coastal morphodynamic model based on the hydrodynamic model of Zheng et al. (2017), combined with an advection-diffusion type suspended sediment transport model and the extended SANTOSS near-bed sediment transport formula of Van der A et al. (2013), to represent the key cross-shore transport mechanisms. The model is are calibrated based on comprehensive measurements from a large-scale laboratory experiment involving regular plunging breaking waves over an evolving sandbar, covering detailed comparisons on hydrodynamics, sediment suspension, transport rates, and bed level evolution. Separate validation using large scale wave flume experiments were also conducted to confirm the model's performance on different conditions. Good agreements are obtained between measurements and model results, which demonstrates the model's ability to reproduce cross-shore sediment transport processes under breaking waves correctly, given that the appropriate parameterizations for intra-wave processes are included. Model results also reveal the onshore near-bed transport is related to wave-induced near-bed streaming, wave skewness and asymmetry, and bed slope effects at different locations across the beach surface. Wave breaking-induced turbulence enhances the near-bed transport within the bed boundary layer which needs to be taken into account in order to achieve good model prediction skills.

U-shaped association between serum IGF2BP3 and T2DM: A cross-sectional study in Chinese population.

To clarify the expression of N6-methyladenosine (m6 A) modulators involved in the pathogenesis of type 2 diabetes mellitus (T2DM). We further explored the association of serum insulin-like growth factor 2 mRNA-binding proteins 3 (IGF2BP3) levels and odds of T2DM in a high-risk population. The gene expression data set GSE25724 was obtained from the Gene Expression Omnibus, and a cluster heatmap was generated by using the R package ComplexHeatmap. Differential expression analysis for 13 m6 A RNA methylation regulators between nondiabetic controls and T2DM subjects was performed using an unpaired t test. A cross-sectional design, including 393 subjects (131 patients with newly diagnosed T2DM, 131 age- and sex-matched subjects with prediabetes, and 131 healthy controls), was carried out. The associations between serum IGF2BP3 concentrations and T2DM were modeled by restricted cubic spline and logistic regression models. Two upregulated (IGF2BP2 and IGF2BP3) and 5 downregulated (methyltransferase-like 3 [METTL3], alkylation repair homolog protein 1 [ALKBH1], YTH domain family 2 [YTHDF2], YTHDF3, and heterogeneous nuclear ribonucleoprotein [HNRNPC]) m6 A-related genes were found in islet samples of T2DM patients. A U-shaped association existed between serum IGF2BP3 levels and odds of T2DM according to cubic natural spline analysis models, after adjustment for body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyeride. Multivariate logistic regression showed that progressively higher odds of T2DM were observed when serum IGF2BP3 levels were below 0.62 ng/mL (odds ratio 3.03 [95% confidence interval 1.23-7.47]) in model 4. Seven significantly altered m6 A RNA methylation genes were identified in T2DM. There was a U-shaped association between serum IGF2BP3 levels and odds of T2DM in the general Chinese adult population. This study provides important evidence for further examination of the role of m6 A RNA methylation, especially serum IGF2BP3 in T2DM risk assessment.

Stabilizing and Destabilizing Breaching Flow Slides

As a result of the dilation of soil matrix, dense submarine sand slopes can temporarily be steeper than the natural angle of repose. These slopes gradually fail by the detachment of individual grains and intermittent collapses of small coherent sand wedges. The key question is whether steep disturbances in a submarine slope grow in size (destabilizing breaching) or gradually diminish (stabilizing breaching) and thereby limit the overall slope failure and resulting damage. The ability to predict whether the breaching failure is stabilizing or destabilizing is also crucial for the assessment of safety of submarine infrastructure and hydraulic structures located along rivers, lakes, and coasts. Through a set of large-scale laboratory experiments, we investigate the validity of an existing criterion to determine the failure mode of breaching (i.e., stabilizing or destabilizing). Both modes were observed in these experiments, providing a unique set of data for analysis. It is concluded that the existing method has limited forecasting power. This was quantified using the mean absolute percentage error, which was found to be 92%. The reasons behind this large discrepancy are discussed. Given the complexity of the underlying geotechnical and hydraulic processes, more advanced methodologies are required.

Micrometre-sized ice particles for planetary science experiments – CoPhyLab cryogenic granular sample production and storage

Abstract In this work, we present a comprehensive investigation into the production, characteristics, handling, and storage of micrometre-sized granular water-ice. The focus of this research is to provide well-characterized analogue samples for laboratory experiments simulating icy bodies found in the Solar system, particularly comets. These experiments are conducted as part of the Comet Physics Laboratory (CoPhyLab) project, an international collaboration aimed at studying cometary processes to gain insights into the underlying physics of cometary activity. Granular water-ice, along with other less abundant but more volatile ices, plays a crucial role in the ejection of gas and dust particles when comets approach the Sun. To facilitate large-scale laboratory experiments, an ice-particle machine was developed, capable of autonomously producing sufficient quantities of granular water-ice. Additionally, a cryogenic desiccator was designed to remove any residual moisture from the ice using liquid nitrogen. The resulting ice particles can be mixed with other materials and stored within the desiccator or a cryogenic transport can, enabling easy shipment to any laboratory, including via air transport. To analyse the ice grains, cryogenic scanning electron microscopy was employed to determine their particle shape and size-frequency distribution. These analyses contribute to a better understanding of the properties of granular water-ice and its behaviour under cryogenic conditions, supporting the objectives of the CoPhyLab project.

Numerical Modeling of Solitary Wave-Induced Flow and Scour around a Square Onshore Structure

Waves or tsunamis in the onshore area could induce severe scour at the structure foundations, threatening the stability of the structure. This paper presents a numerical study of the solitary wave-induced flow and scour around a square onshore structure. A CFD model coupled with hydrodynamic and sediment transport models is first validated through a large-scale laboratory experiment, which shows that the model can well reproduce the flow and scour characteristics. Subsequently, based on the reliable numerical results, the flow field and scour development during wave inundation of the structure are explored. It is found that the development of the simulated scour depth is faster at the early stage compared to that in the experimental result. The results also show that the scour starts at the front corner of the structure, which is also the position of the maximum scour depth. The scour develops rapidly at the early stage and is almost completed in the first half of the wave period. In addition, the results demonstrate that bed scouring increases the wave force on the structure due to the increase in the flow velocity near the bed, which needs to be considered, especially in the shallow-water scour scenario. Finally, a simplified prediction equation is proposed for the temporal development of the scour depth.

Simulation of thermal drains using a new constitutive model for thermal volume change of normally consolidated clays

This paper focuses on the thermo-hydro-mechanical behavior of clay surrounding a thermal drain. A new constitutive model for prediction of thermal volume change of clays is presented that incorporates an improvement to existing models by capturing the effect of initial effective stress on the thermal volume change of normally consolidated clay observed in element-scale tests. A numerical framework with the proposed constitutive model was used to simulate the coupled effects of heat transfer, fluid flow and volume change in clay surrounding a thermal drain. The simulated results were validated using experimental data from a large-scale laboratory experiment on a thermal drain under different thermal and surcharge loads. The results indicate that the required surcharge can be reduced when using a thermal drain in lieu of a conventional vertical drain and a significant increase in the rate of consolidation is observed when using a thermal drain. The proposed constitutive model allows better prediction of thermal volume changes of normally consolidated clays as a function of depth which is important to understand the efficient application of in-situ heating for ground improvement.

Numerical Investigation of Flow Structure and Turbulence Characteristic around a Spur Dike Using Large-Eddy Simulation

Spur dikes provide significant control for flow regimes in river regulation engineering, which can help in the regeneration of stream habitats. However, the narrowing of the flow by spur dike changes the turbulence characteristics. To clarify the turbulence characteristics around the spur dike, the method of large eddy simulation (LES) was used to investigate the horizontal turbulence structure around spur dikes with different discharges in an open-channel flume. The simulations were an exact reproduction of large-scale laboratory experiments, which showed agreement with the experimental results. The distributions of time-averaged streamwise velocity, bed shear stress, and second-order turbulence statistics obtained from the LES were analyzed. An examination of the time series of velocity fluctuation as the probability density function, quadrant analysis, the power density spectra, flow instability, and the vortex separation created in the detached shear layer were estimated. The results accurately revealed the flow field under flow separation, the turbulence statistics inside the separated shear layer, and the vortex structure and emphasized the variation in the different water depths. The results demonstrated that the form of turbulence was not significantly affected by discharge. Moreover, vortex and energy transmission displayed the same periodicity, despite variances in the structural form of turbulence at different water depths. Overall, the results of the study provide an efficient basis for understanding the turbulence around spur dikes, which is crucial for their safe design.

Experimental and Numerical Study on the Composite Column Behavior: Loess Soil Reinforced by Concrete-Stone Column

Stone columns are an effective approach to improving the bearing capacity of weak soils, which has led to increased interest in the improved soil method being further developed and expanded. In addition, enhancing the bearing capacity of stone columns has recently received great attention. This paper studies the effects of embedded concrete parts on the stone columns' bearing capacity and bulging failure. Moreover, arranging solutions to the problem of bulging failure and reduced bearing capacity of stone columns and understanding the stone columns' failure after reinforcement by comparing the results. Stone columns are either embedded in a solid concrete part or unreinforced were examined using large-scale laboratory experiments, and numerical simulation was performed using ABAQUS. The models test with a scale factor of 1:7 was employed. The results demonstrated that using a concrete part on the top of the stone column greatly increases its bearing capacity and the efficiency of the surrounding soil. Concrete-stone columns (CSCs) show stress concentration ratio (n) enhancement and significant resistance to bulging failure deformation. The concrete-stone column shows an enhancement related to increasing the concrete part length; also, the CSCs stiffness increases the surrounding loess soil capacity. The horizontal stresses of CSCs demonstrate the type of column failure behavior; the column may fail due to shear stress in a long concrete part case. Doi: 10.28991/CEJ-2022-08-10-01 Full Text: PDF

Wave runup on composite beaches and dynamic cobble berm revetments

The effects of climate change and sea level rise, combined with overpopulation are leading to ever-increasing stress on coastal regions throughout the world. As a result, there is increased interest in sustainable and adaptable methods of coastal protection. Dynamic cobble berm revetments consist of a gravel berm installed close to the high tide shoreline on a sand beach and are designed to mimic naturally occurring composite beaches (dissipative sandy beaches with a gravel berm around the high tide shoreline). Existing approaches to predict wave runup on sand or pure gravel beaches have very poor skill for composite beaches and this restricts the ability of coastal engineers to assess flood risks at existing sites or design new protection structures. This paper presents high-resolution measurements of wave runup from five field and large-scale laboratory experiments investigating composite beaches and dynamic cobble berm revetments. These data demonstrated that as the swash zone transitions from the fronting sand beach to the gravel berm, the short-wave component of significant swash height rapidly increases and can dominate over the infragravity component. When the berm toe is submerged at high tide, it was found that wave runup is strongly controlled by the water depth at the toe of the gravel berm. This is due to the decoupling of the significant wave height at the berm toe from the offshore wave conditions due to the dissipative nature of the fronting sand beach. This insight, combined with new methods to predict wave setup and infragravity wave dissipation on composite beaches is used to develop the first composite beach/dynamic revetment-specific methodologies for predicting wave runup.

Seismometer Records of Ground Tilt Induced by Debris Flows

ABSTRACT A change in surface loading causes the Earth’s surface to deform. Mass movements, such as debris flows, can cause a tilt large enough to be recorded by nearby instruments, but the signal is strongly dependent on the mass loading and subsurface parameters. Specifically designed sensors for such measurements (tiltmeters) are cumbersome to install. Alternatively, broadband seismometers record translational motion and also tilt signals, often at periods of tens to hundreds of seconds. Their horizontal components are thereby the most sensitive to tilt. In this study, we show how to obtain tilt caused by the passing by of debris flows from seismic measurements recorded within tens of meters of the flow and investigate the usefulness of this signal for flow characterization. We investigate the problem on three scales (1) large-scale laboratory experiments at the U.S. Geological Survey debris-flow flume, where broadband seismometers and tiltmeters were installed for six 8–10 m3 experiments, (2) the Illgraben torrent in Switzerland, one of the most active mass wasting sites in the European Alps, where a broadband seismometer placed within a few meters of the channel recorded 15 debris-flow events with volumes up to 105 m3, and (3) Volcán de Fuego, Guatemala, where a broadband seismometer recorded two lahars. We investigate how the tilt signals compare to debris-flow parameters such as mean normal stresses, usually measured by expensive force plates, and debris-flow height. We model the elastic ground deformation as the response of an elastic half-space to a moving surface load. In addition, we use the model with some simplifications to determine the maximum debris-flow heights of Volcán de Fuego events, where no force plate measurements are available. Finally, we address how and under what assumptions the relatively affordable and straightforward tilt measurements may be utilized to infer debris-flow parameters, as opposed to force plates and other complicated instrument setups.

Trust and Promises over Time

Using a large-scale hybrid laboratory and online trust experiment with and without preplay communication, we investigate how the passage of time affects trust. Communication (predominantly through promises) raises cooperation, trust, and trustworthiness by about 50 percent. This result holds even when three weeks pass between the time of the trustee’s message/the trustor’s decision to trust and the time of the trustee’s contribution choice and even when this contribution choice is made outside of the lab. Delay between the beginning of the interaction and the time to reciprocate neither substantially alters trust or trustworthiness nor affects how subjects communicate. (JEL C91, D83, D91, Z13)

Observed Dust Devil-Like Flow Structures In Large-Scale Turbulent Rayleigh-Bénard Convection

Turbulent Rayleigh-Bénard (RB) convection, a fluid layer heated from below and cooled from above, might be an appropriate tool to reproduce flow phenomena as occurring in a convective atmospheric boundary layer. One of these phenomena is the appearance of so-called dust devils, vortex like flow structures with typical dimensions up to a few tens of meters in diameter and up to a few hundreds of meters in height. Unlike their big brothers, the tornados, start to evolve close to the ground, but the physics of their evolution are still not fully understood. Since field measurements of dust devils are extremely hard to realize (due to their very rare and spontaneous appearance at arbitrarily varying locations), continuous flow measurements in large-scale laboratory experiments may help to overcome this problem. Such measurements in flows of several m³ in volume require optical measurement techniques like particle tracking velocimetry which gains access to the 3-dimensional Lagrangian velocity field. Special attention has to be drawn to the particle seeding of the flow and the imaging of particles. Particles must have neutral density compared to the fluid, and must be large enough to be detected by cameras over a range of several meters. They also should exhibit a prolonged lifetime. In this study, we present experiments conducted in the “Barrel of Ilmenau”, the world-wide largest Rayleigh-Bénard laboratory experiment with 7.15 m in diameter and up to 6.3 m in height using air as working fluid. Neutrally-buoyant helium-filled soap bubbles were injected into the flow and tracked using four cameras. Illumination was carried out with five high-power LEDs in pulsed mode. Reconstruction of the Lagrangian velocity field was performed with Shake-The-Box algorithm. Thus, the major focus of the presented work was to get access to the entire volumetric Lagrangian velocity field in the convection cell on a very long time. Our aim is to discover very rare flow events in turbulent convection, like e.g. dust devil-like vortices or other turbulent superstructures. Measurement data was analyzed to conclude about the applicability of particle tracking velocimetry as suitable measurement technique for large volumetric flows. Finally, an example of a discovered dust-devil like vortex is presented in detail.