Analysis of an unsteady quasi-capillary channel flow with time-resolved PIV and RBF-based super-resolution

Ratz, Manuel; Fiorini, Domenico; Simonini, Alessia; Cierpka, Christian; Mendez, Miguel Alfonso

doi:10.1007/s11998-022-00664-4

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…A similar result was reported by Waghmare et al ( 2012) for purely capillary-dominated flow with no evaporation. The classic counter-rotating vortices shown in similar configurations by Davis et al (1974) and Ratz et al (2023) are not visible in this case.…”

Section: Resultsmentioning

confidence: 70%

“…Both works showed that the common assumption of Poiseuille flow holds until a certain distance from the interface, below which the velocity profile flattens, and radial components appear. Similarly, Ratz et al (2023) analyzed the flow of a quasi-capillary water channel in inertia-dominated conditions and showed that rolling motion under the interface could be produced in advancing and receding conditions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of a Capillary-Driven Flow in Microgravity by Means of Optical Technique

Fiorini,

Carbonnelle,

Simonini

et al. 2023

MultScienTechn

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The motion of a gas-liquid interface along a solid wall is influenced by the capillary forces resulting from the interface's shape and its interaction with the solid, where it forms a dynamic contact angle. Capillary models play a significant role in the management of cryogenic propellants in space, where surface tension dominates the behavior of gas-liquid interfaces. Yet most empirical models have been derived in configurations dominated by viscous forces. In this study, we experimentally investigate the wetting of a low-viscosity, highly wetting fluid in a reduced gravity environment. Our setup consisted of a transparent and diverging U-tube in which capillary forces sustain the liquid motion. Combining particle image velocimetry (PIV) and high-speed backlighting visualization, the experimental campaign allowed for measuring the interface evolution and the velocity field within the liquid under varying gravity levels. This work reports on the preliminary results from the image velocimetry and shows that the velocity profile within the tube is close to parabolic until a short distance from the interface. Nevertheless, classic 1-D models for capillary rise face difficulties reproducing the interface dynamics, suggesting that the treatment of the surface tension in these problems must be reviewed.

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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Characterization of a Capillary-Driven Flow in Microgravity by Means of Optical Technique

Fiorini,

Carbonnelle,

Simonini

et al. 2023

MultScienTechn

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show abstract

“…Figure 11 illustrates both the presence of counterrotating vortices underneath the interface, akin to configurations observed by Dussan E. B. V. Davis (1974) and Ratz et al (2023), and larger re-circulation zones at a further distance. In the reference frame moving with the interface, the meniscus is slower than the fluid along the centerline.…”

Section: Flow Dynamics In the Vicinity Of The Interfacementioning

confidence: 61%

“…The PTV images are pre-processed using the POD-based background removal introduced by Mendez et al ( 2017) while the PTV interrogation was carried out using the Tractrac processing tool (Heyman, 2019). A dynamic Region of Interest (DROI) for the processing was identified by performing a gradient-based edge detection on the POD-filtered images to detect the gas-liquid interface and computing the average velocity (see Fiorini et al (2023a); Ratz et al (2023)). Nevertheless, the PTV acquisitions do not allow for precise detection of the gasliquid interface, which is carried out solely from the recordings in backlight configuration.…”

Section: Measurement Techniquesmentioning

confidence: 99%

An experimental characterization of capillary driven flows in microgravity

Fiorini,

Simonini,

Steelant

et al. 2024

Preprint

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This work investigates the capillary rise dynamics of highly wetting liquids in a divergent U-tube in the microgravity conditions provided by 78th European Space Agency (ESA) parabolic flight. This configuration produces a capillary-driven channel flow. We use image recording in backlight illumination to characterize the interface dynamics and dynamic contact angle of HFE7200 and Di-Propylene Glycol (DPG). For the case of HF7200, we complement the interface measurements with Particle Tracking Velocimetry (PTV) to characterize the velocity fields underneath the moving meniscus. In the experiments with DPG, the liquid column reaches different heights within various experiments, and the measurements show a sharp reduction of the meniscus curvature when the contact line moves from a pre-wet to a dry substrate. In experiments with HFE7200, the interface always moves on a pre-wet surface. Yet a curvature reduction is observed due to the inertial forces on the underlying accelerating flow. The PTV measurements show that the distance from the interface within which the velocity profile adapts to the meniscus velocity shortens as the interface acceleration increases.

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“…This approach blends spatial averaging with ensemble averaging and allows for a larger bin size (beneficial to statistical convergence) without sacrificing the resolution of gradients on the mean flow. Yet, the mean flow is only locally smooth, does not consider physical priors, and statistics are only available in the bin centers In this work, we aim to extend the idea of such blending and combine it with the mesh-less framework proposed in Sperotto et al (2022); Ratz et al (2022a), that was recently released in an open-source toolbox (Sperotto et al, 2024). The mesh-less approach is a new paradigm to PTV data post-processing where the interpolation step is entirely removed and all postprocessing operations (computations of derivatives, correlations or pressure fields) are carried out analytically.…”

mentioning

confidence: 99%

A meshless and binless approach to compute statistics in 3D Ensemble PTV

Ratz,

Mendez

2024

Preprint

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We propose a method to obtain super-resolution of turbulent statistics for three-dimensional ensemble particle tracking velocimetry (EPTV). The method is "meshless" because it does not require the definition of a grid for computing derivatives, and it is "binless" because it does not require the definition of bins to compute local statistics. The method combines the constrained radial basis function (RBF) formalism introduced Sperotto et al. (Meas Sci Technol, 33:094005, 2022) with a kernel estimate approach for the ensemble averaging of the RBF regressions. The computational cost for the RBF regression is alleviated using the partition of unity method (PUM). Three test cases are considered: (1) a 1D illustrative problem on a Gaussian process, (2) a 3D synthetic test case reproducing a 3D jet-like flow, and (3) an experimental dataset collected for an underwater jet flow at Re = 6750 using a four-camera 3D PTV system. For each test case, the method performances are compared to traditional binning approaches such as Gaussian weighting (Agüí and Jiménez, JFM, 185:447-468, 1987), local polynomial fitting (Agüera et al, Meas Sci Technol, 27:124011, 2016), as well as a binned version of the RBF statistics.

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Analysis of an unsteady quasi-capillary channel flow with time-resolved PIV and RBF-based super-resolution

Cited by 6 publications

References 36 publications

Characterization of a Capillary-Driven Flow in Microgravity by Means of Optical Technique

Characterization of a Capillary-Driven Flow in Microgravity by Means of Optical Technique

An experimental characterization of capillary driven flows in microgravity

A meshless and binless approach to compute statistics in 3D Ensemble PTV

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