Microgravity spreading of water spheres on hydrophobic capillary plates

Steub, Laura; Kollmer, Jonathan E.; Paxson, Derek Edwin; Sack, Achim; Pöschel, Thorsten; Bartlett, John; Berman, Douglas A.; Richardson, Yaateh; Louge, Michel Y.

doi:10.1051/epjconf/201714016001

Cited by 3 publications

(7 citation statements)

References 18 publications

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“…In that case, the natural oscillations at large Laplace number would result in deformations of the drop away from the simple spherical cap. This is what we observed in our own microgravity experiments with

La ≃ 6. 10^{5}

, where oscillations at the pinned contact line swayed the interface back and forth from receding to advancing angles …”

Section: Solutionsupporting

confidence: 87%

“…The solid line represents the numerical integration of

{scriptF}_{D}

in Eq. 24 for

δ r^{*} ≃ 10^{- 6}

, which corresponds to water spheres staged by Steub et al at a typical cutoff length of 10 nm; the dashed line is

δ r^{*} ≃ 10^{- 4}

. For

θ < π / 2

, these integrations are very close to Eq.…”

Section: Dynamicssupporting

confidence: 60%

“…As the simulations of Frank et al and our microgravity experiments showed, the contact angle presented by the perforated plane is the effective Cassie‐Baxter angle

\cos θ_{e}^{CB} = (1 - ϵ) \cos θ_{e} - ϵ

which corresponds to “regime VI” for unconnected surface cavities . Therefore, with a perforated surface,

\cos θ_{e}^{CB}

should replace θ e wherever it appears earlier, including

r_{e}^{*}

, but not in Eqs.…”

Section: Imbibitionmentioning

confidence: 71%

“…During the inertial phase, their Lattice‐Boltzmann numerical simulations showed that the permeable surface produced a power law similar to spreading alone, but featuring an exponent α decreasing with the effective Cassie‐Baxter (CB) angle of the triple gas–solid liquid contact line. Our recent microgravity experiments concurred with these results. In addition, our statistical mechanics of the contact angle explained why the unconnected capillaries of Frank, et al had to conform to CB behavior, which is one of six possible regimes of the contact angle on rough surfaces …”

Section: Introductionmentioning

confidence: 82%

“…The model is meant for inertial drops at Bond numbers

ρ g R_{0}^{2} / γ_{ℓ g} ≪ 1

for which gravitational acceleration g is unimportant. It serves as a guide for designing future microgravity experiments of drop spreading on capillary plates, which we first tested at the ZARM free‐fall tower with relatively large liquid spheres. A challenge in comparing such experiments to numerical simulations is that their Laplace number

La \equiv ρ γ_{ℓ g} R_{0} / μ^{2}

a kind of Reynolds number based on capillary speed

γ_{ℓ g} / μ

, is much larger than what existing Lattice‐Boltzmann simulations normally muster, thereby raising the question whether large drops of small viscosity μ , such as water, can be simulated in this way.…”

Section: Introductionmentioning

confidence: 99%

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Model of inertial spreading and imbibition of a liquid drop on a capillary plate

Louge

Sahoo

2017

AIChE Journal

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We outline a low-order Lagrangian model for the inertial dynamics of spreading and imbibition of a spherical liquid cap on a plane featuring independent cylindrical capillaries without gravity. The analysis predicts the relative roles of radial and axial kinetic energy, reveals the critical Laplace number beyond which the drop oscillates, and attributes the exponent of the initial power-law for contact patch radius vs. time to the form of capillary potential energy just after the liquid sphere touches the plate. Figure 3. Interface potential energy G † vs. h for h e 5p=3. Inset: dimensionless contact patch radius r Ã c vs. h.Solid, dashed and dotted lines represent, respectively, expressions for a spherical cap, 11 and corrections consistent with a51=2 and 1/3, respectively.Dashed and solid lines are integrations of Eqs. 28 and 35 for, respectively, equilibrium angles h e 536 and h CB e in Eq. 37. At h CB e , the critical Laplace number is La c ' 2, while it is ' 17; 000 at h e . Inset: predictions of effective drop radius R i 5½3V=ð4pÞ 1=3 relative to its initial value R 0 .

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La ≃ 6. 10^{5}

, where oscillations at the pinned contact line swayed the interface back and forth from receding to advancing angles …”

Section: Solutionsupporting

confidence: 87%

“…The solid line represents the numerical integration of

{scriptF}_{D}

in Eq. 24 for

δ r^{*} ≃ 10^{- 6}

, which corresponds to water spheres staged by Steub et al at a typical cutoff length of 10 nm; the dashed line is

δ r^{*} ≃ 10^{- 4}

. For

θ < π / 2

, these integrations are very close to Eq.…”

Section: Dynamicssupporting

confidence: 60%

“…As the simulations of Frank et al and our microgravity experiments showed, the contact angle presented by the perforated plane is the effective Cassie‐Baxter angle

\cos θ_{e}^{CB} = (1 - ϵ) \cos θ_{e} - ϵ

which corresponds to “regime VI” for unconnected surface cavities . Therefore, with a perforated surface,

\cos θ_{e}^{CB}

should replace θ e wherever it appears earlier, including

r_{e}^{*}

, but not in Eqs.…”

Section: Imbibitionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 82%

“…The model is meant for inertial drops at Bond numbers

ρ g R_{0}^{2} / γ_{ℓ g} ≪ 1

La \equiv ρ γ_{ℓ g} R_{0} / μ^{2}

a kind of Reynolds number based on capillary speed

γ_{ℓ g} / μ

Section: Introductionmentioning

confidence: 99%

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Model of inertial spreading and imbibition of a liquid drop on a capillary plate

Louge

Sahoo

2017

AIChE Journal

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Statistical mechanics of the triple contact line

Louge

2017

Phys. Rev. E

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We outline a statistical mechanics of the triple gas-solid-liquid contact line on a rough plane. The analysis regards the neighborhood of the line as a solid dotted with cavities. It adopts the simplest mean-field statistical mechanics, in which each cavity is either full or empty, while being connected to near neighbors by thin necks. The theory predicts equilibrium angles for advance and recession in terms of the Young contact angle and the joint statistical distribution of two quantifiable geometrical parameters representing specific neck cross-section and specific cavity opening. It attributes contact angle hysteresis to first-order phase transitions among adjacent cavities, as they collectively imbibe or reject liquid. It also calculates the potential energy barriers that hysteresis erects against overcoming contact line pinning. By determining whether the phase transitions can release latent energy, this ab initio analysis distinguishes six regimes, including two metastable recession states. We compare predictions with data for superhydrophobia on microscopic rods; for hysteresis in the "Wenzel state"; and for variations of the advancing contact angle with surface energies of the liquid.

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Interplay of Fogponics and Artificial Intelligence for Potential Application in Controlled Space Farming

Suganob,

Arroyo,

Concepcion

2024

AgriEngineering

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Most studies in astrobotany employ soil as the primary crop-growing medium, which is being researched and innovated. However, utilizing soil for planting in microgravity conditions may be impractical due to its weight, the issue of particles suspended in microgravity, and its propensity to harbor pathogenic microorganisms that pose health risks. Hence, soilless irrigation and fertigation systems such as fogponics possess a high potential for space farming. Fogponics is a promising variation of aeroponics, which involves the delivery of nutrient-rich water as a fine fog to plant roots. However, evaluating the strengths and weaknesses of fogponics compared to other soilless cultivation methods is essential. Additionally, optimizing fogponics systems for effective crop cultivation in microgravity environments is crucial. This study investigated the interaction of fogponics and artificial intelligence for crop cultivation in microgravity environments, aiming to replace soil-based methods, filling a significant research gap as the first comprehensive examination of this interplay in the literature. A comparative assessment of soilless fertigation and irrigation techniques to identify strengths and weaknesses was conducted, providing an overview through a literature review. This highlights key concepts, methodologies, and findings, emphasizing fogponics’ relevance in space exploration and identifying gaps in current understanding. Insights suggest that developing adaptive fogponics systems for microgravity faces challenges due to uncharacterized fog behavior and optimization complexities without gravity. Fogponics shows promise for sustainable space agriculture, yet it lags in technological integration compared with hydroponics and aeroponics. Future research should focus on microgravity fog behavior analysis, the development of an effective and optimized space mission-compatible fogponics system, and system improvements such as an electronic nose for an adaptive system fog chemical composition. This study recommends integrating advanced technologies like AI-driven closed-loop systems to advance fogponics applications in space farming.

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Microgravity spreading of water spheres on hydrophobic capillary plates

Cited by 3 publications

References 18 publications

Model of inertial spreading and imbibition of a liquid drop on a capillary plate

Model of inertial spreading and imbibition of a liquid drop on a capillary plate

Statistical mechanics of the triple contact line

Interplay of Fogponics and Artificial Intelligence for Potential Application in Controlled Space Farming

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