Improved phase field model for two-phase incompressible flows: Sharp interface limit, universal mobility and surface tension calculation

To explore the influence of inter-formation variables on swimming performance during fish schooling, this paper adopts the sharp interface immersed boundary method based on virtual cells to conduct numerical research on the swimming of three-fish and four-fish swarms with different formations and spacings. The study finds that both streamwise spacing and lateral spacing have significant impacts on the swimming performance of fish schools. In the three-fish formation, when the tandem arrangement has a streamwise spacing of 1.3 times the body length (L), the trailing fish achieve the highest swimming efficiency; when the parallel arrangement has a lateral spacing of 0.25L, the fish in the middle position exhibits the optimal swimming performance. In the four-fish formation model, fish in symmetric positions within the same swarm have similar hydrodynamic performance. For the diamond formation, under the configuration of streamwise spacing 1.2L and lateral spacing 0.5L, the propulsive efficiency of the trailing fish is markedly diminished; however, for the rectangular formation, all trailing fish obtain lower swimming efficiency, and a stable 2S-type vortex structure appears in the wake under the configuration of streamwise spacing 1.5L and lateral spacing 0.5L, which is conducive to thrust generation. The conclusions of this paper can provide certain hydrodynamic advantages and support the development of bionic underwater vehicles and robot technology.

The growth of the semiconductor compound barium sulfide (BaS) is being studied using atomistic methods and mesoscopic theoretical modeling. Material properties such as phase densities, enthalpies, specific latent heat, Gibbs free energy difference, liquid diffusion coefficient, interfacial free energies, and stiffness for different crystal faces of the crystal lattice of BaS are obtained by molecular dynamics (MD). The growth kinetics studied by the MD method show close to linear growth velocity dependence in the range of undercoolingΔT<800 K with a slight abnormal acceleration bend caused by the nucleation of crystals in the bulk liquid. The hodograph equation, as the sharp interface limit of the kinetic phase field (KPF) and as the mesoscopic approach to modeling, well predicts the growth kinetics of crystal phases in BaS atΔT<500 K and the whole tendency of growth kinetics atΔT>500 K. The discussion on the non-linear behavior of the dynamic diffuse interface of BaS crystal faces width is given upon predictions by MD and KPF methods.

ABSTRACT Chemo‐mechanically coupled phenomena such as stress‐driven diffusion and diffusion‐induced stresses are of high interest, for example, in battery materials and metals. In this work, a chemo‐mechanically fully coupled multiphase‐field model for a multicomponent system is derived and validated with a sharp interface solution. Ensuring mechanical compatibility, the model accounts for balance equations on singular surfaces and the Hadamard jump conditions. The models' capability to address stress‐driven diffusion and diffusion‐induced stresses is demonstrated through the presentation of an illustrative diffusion example.

To improve cardiac motion representation and reduce artifacts for cardiac- and respiratory-resolved imaging through a synergistic combination of retrospective cardiac phased array RF focusing and rigid respiratory motion compensation (MoCo). We incorporated cardiac receive focusing using region-optimized virtual coils (ROVir) and MoCo into cardiac- and respiratory-resolved low-rank tensor (LRT) reconstruction, hypothesizing that the combination of MoCo + ROVir would prioritize the LRT representation of cardiac motion over respiratory motion. We compared LRT, MoCo-LRT, ROVir-LRT, and the proposed MoCo + ROVir-LRT reconstructions of retrospective data from N = 24 pediatric patients with congenital heart disease (CHD) scanned at 3.0 T using ROCK-MUSIC. Technical evaluation metrics included the proportion of cardiac-to-respiratory motion energy in self-gating lines, cardiac motion priority in the temporal basis, flickering energy, and edge sharpness in end-expiratory cardiac cine. Reconstructed cardiac cines were scored by two expert image readers. MoCo + ROVir significantly increased the proportion of cardiac-to-respiratory motion energy in self-gating lines (p < 0.001) and prioritized cardiac motion in the temporal basis (p < 0.001). MoCo + ROVir reduced flickering energy in cardiac cine images (p < 0.001), sharpened the liver-lung interface (p < 0.001), and improved flickering-specific scores (p = 0.001). Myocardium-blood pool interface sharpness (p = 0.831), cardiac-specific image scores (p = 0.188), and vascular-specific scores (p = 0.901) were not significantly different. Together, these two techniques allowed 3.7-5.2× faster reconstruction times versus LRT-only. The synergy of MoCo + ROVir successfully prioritized cardiac motion, suppressed respiratory motion, and reduced flickering artifacts, with an added benefit of accelerating reconstruction times. The improved respiratory motion handling may provide an avenue for free-breathing cardiac scans in pediatric patients with CHD.

Two-dimensional (2D) materials are considered promising candidates for next-generation electronic devices, especially field-effect transistors (FETs). However, deposition of a uniform dielectric layer on 2D materials with an inert surface is challenging. Herein, the integration of HfOx on graphene is demonstrated through simple thermal oxidation of HfS2 precursor to form a high-quality HfOx/graphene stack. The thermal treatment enables complete conversion from HfS2 into ultrathin HfOx with an atomically smooth surface and sharp interface with graphene. The transformed thin HfOx shows decent dielectric properties, including a high dielectric constant of 18 and a robust breakdown field of 10 MV/cm. High-performance MoS2 FETs based on HfOx/graphene gate stack demonstrate a high ON/OFF ratio of 106, a low subthreshold swing of 75 mV/dec, and a low leakage current. Resistive switching devices were also fabricated showing coexistence of volatile and nonvolatile switching, and a steep switching slope. This nondestructive integration of high-quality high-κ dielectrics on 2D materials opens up possibilities for developing multifunctional 2D electronics.

Sharp interface modeling and simulations of two-phase ferrofluid flows

3D Arbitrary Lagrangian–Eulerian approach for multiphase flow with an efficient sharp interface tracking

Wave breaking on coastal slopes drives critical nearshore processes, yet resolving its multiphase dynamics remains challenging due to interface smearing in numerical models and measurement limitations in aerated regions. This study investigates the hydrodynamics of two spilling breaker conditions on a 1:15 slope, with emphasis on propagation behavior, interface evolution, and spectral energy transfer. A comparative analysis of wave morphology between the geometric reconstruction-based IsoAdvector and the algebraic compression-based Multi-dimensional Universal Limiter for Explicit Solution (MULES) methods was conducted using numerical wave flumes, supported by synchronous high-resolution measurements of free surface elevation and flow fields via ultrasonic wave gauges and particle image velocimetry. The breaking process was categorized into four sequential phases: pre-breaking deformation, aerated surface layer formation, bubble-laden interface development, and fragmented free-surface stabilization. Comparative analysis revealed distinct methodological performances: IsoAdvector maintained a sharp interface (&amp;lt;2 cells thick) with low mesh sensitivity and achieved a higher refined index of agreement (dr) with experimental surface elevation, accurately capturing crest curvature, jet dynamics, and bubble formation. In contrast, MULES produces a diffuse interface (&amp;gt;2 cells thick) with mesh-dependent phase shift; however, it offered approximately 4.7 % higher computational efficiency in fine-mesh simulations. Accordingly, IsoAdvector is recommended for high-fidelity interface-resolved studies, while MULES is suitable for large-scale applications prioritizing computational economy. Spectral analysis further showed that increased wave height intensifies nonlinear interactions, resulting in earlier breaking, broader energy distribution, and enhanced dissipation. These findings provide key insight into nearshore wave transformation and guidance for selecting numerical approaches in breaking wave simulations.

Abstract Boiling heat transfer, particularly in subcooled conditions, plays a critical role in advanced thermal management systems such as nuclear reactors, data centers, and aerospace cooling modules. This study presents a numerical investigation of nucleate subcooled boiling across five subcooling levels. Ansys Fluent was customized with user-defined functions (UDFs) to resolve the coupled thermal–fluid interactions by directly modeling interfacial mass transfer, enforcing saturation temperature at the interface, and maintaining interface sharpness. The framework demonstrates strong agreement with both experimental and semi-empirical benchmarks, with average errors below 11%. Results show a clear trend of decreasing departure diameter (from 2.3 to 1.6 mm) and increasing horizontal thermal film thinning length (from 0.8 to 1.2 mm) as the subcooling level rises from 1 to 5 K. Furthermore, as subcooling increases from 1 K to 5 K, local heat transfer coefficients rise from 90,000 to 115,000 W/m2·K. Velocity magnitudes near the interface increase due to stronger condensation-induced momentum transfer, with peak values rising from 0.30 m/s at 1 K to 0.82 m/s at 5 K, while the shear stress influence region simultaneously expands from 2.2 mm to 3.4 mm and its magnitude increases from 90 Pa to 320 Pa. These findings provide new insights into the interplay of subcooling, interfacial heat transfer, and fluid motion, offering predictive capability for the design and optimization of next-generation phase-change cooling technologies.

The paper proposes an energy-based adaptive sampling strategy to enhance the performance of the deep unfitted Nitsche method (DUNM) for elliptic interface problems. Instead of relying on fixed or random training points, the proposed refinement indicator dynamically concentrates samples in high-energy regions, including sharp coefficient jumps and interface singularities. This targeted allocation improves both accuracy and efficiency compared to random sampling. Numerical experiments in both two- and three-dimensional settings demonstrate that the method achieves robust accuracy and efficiency across diverse scenarios, from standard geometries to highly irregular interfaces, while effectively handling high-contrast coefficients and multi-subdomain configurations. These results confirm that the proposed adaptive strategy not only reduces training cost but also ensures reliable performance in complex interface problems.

Weak solutions m\colon\Omega\subset\mathbb{R}^{2}\to\mathbb{R}^{2} of the eikonal equation, \begin{align*}|m|=1\text{ a.e.} \quad \text{and} \quad \mathrm{div} m =0,\end{align*} arise naturally as sharp interface limits of bounded energy configurations in various physically motivated models, including the Aviles–Giga energy. The distributions \mu_{\Phi}=\mathrm{div}\Phi(m) , defined for a class of smooth vector fields \Phi called entropies, carry information about singularities and energy cost. If these entropy productions are Radon measures, a long-standing conjecture predicts that they must be concentrated on the 1-rectifiable jump set of m –as they do if m has bounded variation (BV) thanks to the chain rule. We establish this concentration property, for a large class of entropies, under the Besov regularity assumption \begin{align*}m\in B^{1/p}_{p,\infty} \quad\Longleftrightarrow\quad\sup_{h\in \mathbb R^2\setminus\lbrace 0\rbrace} \frac{\|m(\cdot +h)-m\|_{L^p}}{|h|^{1/p}} &lt;\infty,\end{align*} for any 1\leq p&lt;3 , thus going well beyond the BV setting ( p=1 ) and leaving only the borderline case p=3 open.

Cuprous oxide (Cu2O) is a promising photoelectrochemical (PEC) material, but its performance is hindered by poor charge separation and photocorrosion. These limitations can be effectively mitigated by constructing semiconductor heterojunctions that promote interfacial charge transfer and improve structural stability. Herein, we present a type-II Cu2O@Cu-HHTP core-shell heterostructure interface for highly efficient PEC sensing of H2S. The successful construction of the core-shell Cu2O@Cu-HHTP heterostructure is verified by material characterization. In particular, the new HR-TEM images reveal a sharp and coherent interface between the Cu2O and Cu-HHTP phases. The optimized interfacial charge transfer between Cu2O and the Cu-HHTP shell enables a markedly enhanced photocurrent of 3.81 μA, nearly five times higher than pristine Cu2O (0.84 μA). The resulting sensor exhibits an ultralow detection limit of 3.40 nM and an exceptionally broad linear range from 10.0 nM to 100.0 μM. Mechanism studies indicate that exposure to H2S forms Cu9S8 at the heterojunction, which disrupts its structure, accelerates charge recombination, and attenuates the photocurrent. Compared with existing sensing technologies, it demonstrates superior sensitivity and achieves the lowest detection limit reported to date among sensors based on metal oxides or MOFs materials. Enabling accurate detection of endogenous H2S in rat cerebrospinal fluid through in vivo microdialysis, demonstrating strong potential for biological monitoring. This work highlights an effective interfacial engineering strategy to boost charge separation and broaden detection capability, offering a robust platform for ultrasensitive PEC sensing of H2S in environmental and biomedical contexts.

Within the phase-field framework, matrix cracking and interfacial debonding in composites are simultaneously captured by introducing dual phase-field variables. To smooth a sharp interface, an interface-related phase-field variable is defined, and equivalent material parameters are formulated using interpolation functions that depend on the interface phase-field distribution. On the basis of the phase-field cohesive zone model, a crack phase-field variable is employed to capture material failure, enabling the characterization of various interfacial failure modes and quantification of the effect of interface strength on fracture behavior. Numerical results demonstrate that the interpolation function order significantly affects structural response: higher-order interpolations expand the low-fracture-energy region near the interface, reduce the predicted peak load, and promote a transition in the crack path from interfacial debonding to matrix cracking. This transition is attributed to the smoother variations in the local stiffness and fracture resistance introduced by higher-order interpolations. Moreover, increasing the interface strength enhances the load-bearing capacity and drives the fracture mode toward matrix-dominated cracking. For fiber-reinforced composite cases, the results obtained from higher-order interpolations closely match those derived from cohesive element models, validating the proposed approach. This framework offers a robust computational tool for investigating the interaction between interfacial debonding and matrix cracking, and provides deeper understanding of how interface parameterization influences fracture behavior in composites.

To realize a chemical diffusion experiment for simple quantitative analysis of one-dimensional diffusion profiles requires the fabrication of a planar and chemically sharp interface between two phases, one serving as the diffusion source and the other as the material to be studied. We demonstrate a thin film source on top of single crystals or epitaxial films for the example of cobalt (II) oxide (CoO) grown on top of SrTiO3 (STO) by ion beam sputtering. After deposition at room temperature, a nearly single-crystalline epitaxial film with a flat and chemically sharp interface is present. Diffusion annealing leads to a partial formation of the Co3O4 phase. We report the conditions where compact and stable CoO layers with flat interface are maintained, serving as a constant source for Co diffusion. Exemplarily, the formation of a Co-diffusion profile is studied by using three different methods: energy dispersive X-ray spectroscopy in a transmission electron microscope, atom probe tomography, and time-of-flight secondary ion mass spectroscopy. The origin of differences in the diffusion constant probed on different sample scales is discussed.

Development of a new THINC/WLIC method based on a separate evaluation of the geometrical fidelity and the interface sharpness

VOF and sharp interface CFD analyses of a liquid methane self-pressurization experiment in 1 g and microgravity

As dynamic random-access memory continues to scale down, the feasible physical thickness of the capacitor dielectric layer continuously decreases, thus, controlling the low-k interfacial layer formed at the ZrO2 dielectric/TiN electrode interface is becoming crucial. The interfacial layer reduces the capacitance density and increases the leakage current density, and both of them contribute to the degradation of the overall properties of the capacitor. In this study, two precursors were compared: the commonly used Cp-based Zr precursor, Cp-Zr(NMe2)3 [Cp-Zr] and the novel MePrCp-Zr(NMe2)3 [MePrCp-Zr] precursor, with the two terminal hydrogens of the Cp ligand substituted with Me and Pr groups. MePrCp-Zr was confirmed to suppress the formation of low-k interfacial layers such as TiOx or TiOxNy at the initial ZrO2 growth stage, owing to its higher reactivity than Cp-Zr. Furthermore, analysis of oxidation behavior using TiN and Ru bottom electrodes clearly revealed that the application of MePrCp-Zr led to improved interfacial sharpness compared to Cp-Zr. Electrical properties also confirmed enhanced interfacial properties, indicating that the equivalent oxide thickness decreased by 0.38 nm with the MePrCp-Zr precursor compared to Cp-Zr. This ligand-engineering strategy provides a scalable approach to achieving ultrathin high-k dielectrics with stable interfaces, enabling reliable capacitor integration for next-generation DRAM and advanced logic technologies.

An analytical model for the nucleation of edge misfit dislocations in cylindrical core-shell nanowires with a diffuse interface boundary is developed. The model is formulated within the framework of linear isotropic elasticity theory and accounts for the interplay between the nanowire’s geometry, interface diffuseness, and lattice mismatch. By evaluating the total energy change associated with dislocation formation, we systematically analyze the dependence of energetic favorability of dislocation nucleation on the core/shell radius ratio, diffuse interface width, and misfit parameter. The results demonstrate that sharp interfaces maximize the energy gain from dislocation formation, whereas diffuse interfaces suppress it, particularly in nanowires with thin cores. The optimal dislocation nucleation site is primarily governed by geometry features and only weakly influenced by misfit parameter. A critical misfit parameter is identified, above which the nanowire coherent state becomes unstable. The analysis reveals that while broader diffuse interfaces reduce the tendency for relaxation process, increased lattice mismatch promotes it.

AlGaN-based deep-ultraviolet vertical-cavity surface-emitting lasers (DUV VCSELs) have shown a great application potential in optical atomic clocks, maskless photolithography, etc. Nevertheless, the uncontrolled cavity length-induced detuning issue, i.e., the difference between the resonance wavelength and gain peak, severely impairs the device performance. Herein, a DUV-VCSEL strategy featuring the uniform nanometer-class control of the cavity length in a 4-in wafer is proposed in the DUV framework based on GaN templates, which ensures the wafer-scale removal of sapphire substrates by laser lift-off, and then provides space for the subsequent deposition of dielectric distributed Bragg reflector (DBR). It is more significant that the strategy brings about a GaN/AlGaN sharp interface with an Al composition difference up to 80%, whereby self-terminated etching with an ultrahigh selectivity of 100:1 is achieved. The cavity length is hence accurately determined by epitaxy itself instead of the fabrication process, so as to minimize the detuning. As such, 285.6-nm optically pumped DUV VCSELs with double dielectric DBRs are fabricated, exhibiting a record low threshold of 0.38 MW cm-2 and a narrow linewidth of 0.11nm. What's more, the lasing wavelength varies within 1.9nm across the 4-in wafer, indicating a cavity length variation of only 0.81%.