Preprints
Filtering by Subject: Fluid Dynamics
Decompression, self-leveling, and wobble decay of bubble rings released by scuba divers
Published: 2026-10-28
Subjects: Dynamic Systems, Fluid Dynamics, Oceanography, Ordinary Differential Equations and Applied Dynamics
Scuba divers blow bubble rings, hollow vortex rings with a gas core that expands as the ring rises because the water pressure drops with every meter of ascent. Classical theory keeps the gas volume fixed and treats only level rings, and the one earlier estimate of the expansion, for a laboratory tank, found it small. Here the ring is modeled as a thin hollow vortex ring with a core that obeys [...]
antasena: A Python Library for Nitrox Diving Calculations
Published: 2026-10-24
Subjects: Dynamic Systems, Fluid Dynamics, Numerical Analysis and Computation, Oceanography
We present antasena, an open-source Python library for calculations that underlie diving with nitrox, oxygen-nitrogen mixtures richer in oxygen than air. It computes depth limits, equivalent depths, inert-gas uptake, no-decompression limits, staged decompression schedules, central-nervous-system and pulmonary oxygen exposure, real-gas cylinder contents, and partial-pressure blending, and its [...]
Settling-driven Rayleigh–Taylor instability in a pre-existing turbulent field
Published: 2026-10-24
Subjects: Fluid Dynamics, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Physics
Vertical particle transport controls environmental processes ranging from sediment deposition and the export of organic material and microplastics to the fate of minerals released for carbon dioxide removal. When a particle-laden layer overlies denser water, particles destabilize the interface and descend collectively as convective plumes, far faster than individual settling. Yet this mechanism [...]
Interior-fold and endpoint transitions in finite-depth capillary-gravity ship wakes
Published: 2026-10-23
Subjects: Fluid Dynamics, Oceanography
We study how finite water depth changes the principal stern caustics and wave patterns of linear capillary-gravity waves generated by a steadily moving pressure source on an inviscid fluid of uniform depth. Using the dispersion relation and ray directions relative to the source, we determine the conditions for caustic formation. Let H denote the water depth divided by the capillary length. No [...]
Paragliders as probes of the Alpine boundary layer: sink polars from 86 000 flight logs and the flow field of a valley
Published: 2026-10-15
Subjects: Atmospheric Sciences, Fluid Dynamics, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Physics
Paraglider flight logs are a dense, free and continuous record of the air over mountains: every thermal day, hundreds of pilots fly for hours along the slopes and across the valleys and record their vertical speed once per second. The obstacle is that a vario measures the air plus the sink of the glider, and the sink polars of paragliders are unknown. We obtain them from the logs themselves. [...]
An Idealized Model of Buoyant Gas Spreading and Silt Release beneath Rough Cave Ceilings
Published: 2026-10-06
Subjects: Fluid Dynamics, Hydrology, Partial Differential Equations, Sedimentology, Statistical, Nonlinear, and Soft Matter Physics
Gas exhaled by open-circuit divers collects under the ceilings of submerged caves, migrates along the rock, and dislodges loose silt that then falls through the passage, a process that cave divers call percolation. This study develops an idealized model of the process. Buoyant gas under a self-affine rough ceiling is treated as a quasi-static sequence of pools that fill to their spill points, [...]
Stokes flow in logarithmic-viscosity space: velocity renormalization and a reference-operator formulation
Published: 2026-08-13
Subjects: Fluid Dynamics, Physical Sciences and Mathematics, Planetary Geophysics and Seismology
Effective viscosity in crystalline solids commonly depends exponentially on temperature, pressure, composition and other state variables, producing spatial variations over many orders of magnitude and making variable-viscosity Stokes flow numerically demanding. We develop an exact, coordinate-independent reformulation using logarithmic viscosity \(\Lambda=\ln(\eta/\eta_0)\) and renormalized [...]
Fourier Neural Operator Surrogates for Hysteretic Multiphase Flow in Heterogeneous Geological CO2 Storage Reservoirs
Published: 2026-08-03
Subjects: Earth Sciences, Fluid Dynamics, Physical Sciences and Mathematics
Modeling hysteresis in heterogeneous field-scale reservoirs is essential for estimating residual CO2 trapping capacity and assessing the security of geological storage. This requires accounting for both relative permeability hysteresis and capillary pressure hysteresis, which control path-dependent multiphase flow and the spatial distribution of trapped gas. Because maximum residual gas [...]
Deep Neural Network-Based Inversion of Turbidites in Confined Basins
Published: 2026-07-11
Subjects: Artificial Intelligence and Robotics, Fluid Dynamics, Geology, Sedimentology
Turbidites generated by large earthquakes and other geological events are commonly preserved in small, topographically confined basins along active continental margins. Reconstructing flow conditions from these deposits is essential for assessing past hazards; however, existing inverse models have been validated only for unconfined settings, and their applicability to confined basins remains [...]
A machine learning approach for detecting biofouling in oceanographic data
Published: 2026-07-11
Subjects: Artificial Intelligence and Robotics, Fluid Dynamics, Numerical Analysis and Computation, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Autonomous ocean observing platforms collect long-term biogeochemical time series, but sensor degradation from biofouling introduces progressive biases that contaminate the climate record. This work focuses on the BGC-Argo fleet of profiling floats, where optical sensors measuring chlorophyll-a and backscatter are particularly susceptible to biofouling. Current detection relies on per-float [...]
Modification of Antarctic geothermal heat flux by groundwater flow
Published: 2026-06-13
Subjects: Fluid Dynamics, Glaciology
The geothermal heat flux to the bed of the ice in Antarctica is important for ice flow and basal meltwater production, but is also highly uncertain. In particular, it is thought that groundwater flow in sedimentary basins could modify the geothermal heat flux to the ice bed by advecting heat, but this process is unaccounted for in current models. In this paper, we develop a mathematical model to [...]
Modelling the Evolution of Elliptical Röthlisberger Channels
Published: 2026-06-12
Subjects: Fluid Dynamics, Glaciology, Other Mathematics
Subglacial water flow is critical to basal sliding and ice dynamics. Modelling the coupled evolution of subglacial drainage and ice flow remains challenging, however. This study investigates the evolution of the basal ice-water interface by analysing heat and fluid flow in idealised englacial channels. We extend the classical Röthlisberger model for circular channels to elliptical channel [...]
Trapped Lee-Wave Resonance Determines Antarctic Megadune Wavelength
Published: 2026-05-23
Subjects: Applied Statistics, Categorical Data Analysis, Design of Experiments and Sample Surveys, Earth Sciences, Fluid Dynamics, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Mineral Physics, Other Earth Sciences, Paleontology, Physics, Planetary Geology, Planetary Geomorphology, Planetary Geophysics and Seismology, Planetary Glaciology, Planetary Hydrology, Planetary Mineral Physics, Planetary Sciences, Planetary Sedimentology, Sedimentology, Statistical Methodology, Statistical Models, Statistics and Probability, Stratigraphy
Snow megadunes cover 5×105 km2 of the East Antarctic plateau, biasing surface mass balance estimates and overprinting ice-core signals—yet their 2–5 km wavelength has lacked a quantitative selection mechanism for two decades. We first falsify the standard formula λ∗ = 2πU0/N through a calibration-free spatial test: eight REMA 2 m tiles across two independent locations at 81.5–82.0°S show no [...]
Learning unresolved coastal dynamics in hydrodynamic models
Published: 2026-05-02
Subjects: Fluid Dynamics, Oceanography
Coastal hydrodynamic models play a vital role in understanding and predicting flooding, but practical computational constraints and uncertainties in boundary conditions and bathymetry lead to systematic errors in local sea level. We show that much of this error is not random but reflects a stable, site-specific response that can be learned from model output and observations. We develop a [...]
A prescribed wave probe reveals phase hidden vortex force memory in turbulence
Published: 2026-04-16
Subjects: Fluid Dynamics, Physical Sciences and Mathematics
Phase averaging closes the equations of multi scale flows by removing bilinear couplings with vanishing one time means. Their two time correlations can still survive. We test this distinction for waves passing through turbulence. We study the stochastic vortex force in direct numerical simulation of homogeneous isotropic turbulence. This wave vorticity coupling is removed by classical phase [...]