We consider an isotropic compressible non-dissipative fluid with broken parity subject to free surface boundary conditions in two spatial dimensions. The hydrodynamic equations describing the bulk dynamics of the fluid and the free surface boundary conditions depend explicitly on the parity breaking non-dissipative odd viscosity term. We construct an effective action which gives both bulk hydrodynamic

The solidification of liquid bridge plays an important role in many applications. Previous research on droplet solidification has found that supercooling and gravity have certain effects on physical properties and droplet shape during solidification. In this paper, axisymmetric liquid bridge solidification is studied from theory and experiment. A fixed contact line model, considering both the effects

We consider the use of probabilistic neural networks for fluid flow {surrogate modeling} and data recovery. This framework is constructed by assuming that the target variables are sampled from a Gaussian distribution conditioned on the inputs. Consequently, the overall formulation sets up a procedure to predict the hyperparameters of this distribution which are then used to compute an objective function

An essential ingredient of turbulent flows is the vortex stretching mechanism, which emanates from the non-linear interaction of vorticity and strain-rate tensor and leads to formation of extreme events. We analyze the statistical correlations between vorticity and strain rate by using a massive database generated from very well resolved direct numerical simulations of forced isotropic turbulence in

Doubly diffusive convection is studied in a three-dimensional enclosure of square horizontal cross-section. Previous studies have focused on the emergence of steady states and revealed that the primary instability from the conduction state gives rise to subcritical branches of spatially localized states that undergo snaking. These states are further destabilized by the presence of the twist instability

High Reynolds number wind tunnels are essential tools for testing theories of turbulence. This need has led to the construction of tunnels that use compressed gases as the working fluid, and such facilities have given new insights into the behavior of turbulence in wall-bounded flows. Here, we focus on results obtained at Princeton using the Superpipe and the High Reynolds number Testing Facility that

Visualization experiments and pore network models on evaporation of capillary porous media are presented in this work. We show that in a simple model porous medium the pores occupied by gas can be refilled with liquid, snapping off a gas bubble, which then moves to a stable configuration. This phenomenon, referred to as capillary instability, is induced due to heterogeneity in wettability of the pore

For a family of oscillatory Stokes layers, the spatio-temporal evolution of impulsively excited disturbances is investigated, using direct numerical simulations of the linearised Navier-Stokes equations. The semi-infinite planar Stokes layer is modified to incorporate a low-amplitude, high-frequency harmonic, which provides a simplified model of the external noise found in physical experiments. For

There has been a growing interest in implementing state-resolved models for flowfield calculations of high-speed reentry applications that are characterized by regions of strong non-equilibrium. To this end, the present work provides a technique to rigorously compute transport collision integrals for vibrationally excited molecules. Collision dynamics calculations are extended to include state-to-state

We demonstrate that two surface waves propagating at a small angle 2θ to each other generate large-scale (compared to the wavelength) vertical vorticity owing to hydrodynamic nonlinearity in a viscous fluid. The horizontal geometric structure of the induced flow coincides with the structure of the Stokes drift in an ideal fluid, but its steady-state amplitude is larger and it penetrates deeper into

We investigate through numerical simulations of the Navier-Stokes equations the influence of the surface roughness on the fluid flow through fracture joints. Using the Hurst exponent H to characterize the roughness of the self-affine surfaces that constitute the fracture, our analysis reveal the important interplay between geometry and inertia on the flow. Precisely, for low values of Reynolds numbers

When an object impacts the free surface of a liquid, it ejects a splash curtain upwards and creates an air cavity below the free surface. As the object descends into the liquid, the air cavity eventually closes under the action of hydrostatic pressure (deep seal). In contrast, the surface curtain may splash outwards or dome over and close, creating a surface seal. In this paper we experimentally investigate

We present a theoretical investigation of liquid imbibition into capillaries with axially varying geometry. We show that using appropriate geometry and wettability converging capillaries, in principle, can act as a liquid diode. We explain the underlying mechanics and conditions that make converging capillary a liquid diode. Further, we describe a methodology to enhance the rate of liquid imbibition

It is known that a horizontal two-layer liquid film heated from above is subject to a longwave oscillatory Marangoni instability. The action of a time-periodic modulation of interfacial heat consumption on the temporal dynamics of nonlinear Marangoni waves is investigated. The problem is studied numerically in the framework of longwave amplitude equations. We focus on the phenomenon of synchronization

We report on Rayleigh-B'enard convection with strongly varying fluid properties experimentally and theoretically. Using pressurized sulfur-hexafluoride (SF6) above its critical point, we are able to make measurements at mean temperatures (Tm) and pressures (Pm) along Prandtl-number isolines in the (T,P) parameter space. This allows to keep the mean Rayleigh- (Ram) and Prandtl number (Prm) constant

We analyze the interfacial instability of a thin film confined between a rigid surface and a pre-stretched elastic sheet, triggered by non-uniform electro-osmotic flow. We derive a nonlinear viscous−elastic equation governing the deformation of the elastic sheet, describing the balance between viscous resistance, the dielectric and electro-osmotic effects, and the restoring effect of elasticity. Our

The merging of a single row of plumes in a quiescent environment has been studied using irrotational flow theory (Rooney 2015, {J. Fluid Mech.}, vol.~771, R1). The present study extends this theory by considering (i) two parallel rows of plumes in a quiescent environment, and, (ii) a single row of plumes in a crosswind, with and without a pressure drag term. For plumes in two rows with and without

Using classical as well as ab initio molecular dynamics simulations, we calculate the frequency-dependent shear viscosity of pure water and water–glycerol mixtures. In agreement with recent experiments, we find deviations from Newtonian-fluid behavior} in the THz regime. Based on an extension of the Maxwell model, we introduce a viscoelastic model} to describe the observed viscosity spectrum of pure

Gradients of chemical potentials in a multiphase system induce mass transport and thus motion of interfaces. We probe the displacement of oil on a solid substrate immersed in water through this osmosis phenomenon by using microfabricated cavities that play the role of dead-end pores where oil is trapped in presence of salt crystals. The efficiency of oil removing from the model crevices is shown to

A hypersonic shock wave/turbulent boundary layer interaction (STBLI) is investigated using direct numerical simulation (DNS). The geometry is an 8∘ compression ramp, and the flow conditions upstream of the interaction are Mach 7.2 and Reθ=3500. Consistent with experiments at similar conditions, the flow is found to be attached in the mean, although the DNS shows that the probability of observing reversed

Numerical solutions of the Enskog-Vlasov (EV) equation are used to determine the velocity distribution function of atoms spontaneously evaporating into near-vacuum conditions. It is found that an accurate approximation is provided by a half-Maxwellian including a drift velocity combined with different characteristic temperatures for the velocity components normal and parallel to the liquid-vapor interface

The relative influence of circulation and buoyancy on fire whirls (FW), blue whirls (BW), and the transition between these regimes of a whirling flame is investigated using a combination of experimental data and scaling analyses. FWs are whirling, turbulent, cylindrical yellow (sooting) flame structures that form naturally in fires and are here created in laboratory experiments. In contrast, a BW is

Linear damping is widely applied in experiments and fluid models to describe the large-scale dissipation that absorbs upscale energy transfers in two-dimensional (2D) turbulence. However, in many systems, it is not justified that linear damping is a good model and it is hard to obtain the damping coefficient from directly measurable quantities. Based on the forcing-scale resolving structure-function

We present a series of two-dimensional (2D) numerical simulations on thermal convection in a square and an octagonal enclosure, with heated bottom and cooled top surfaces for the range of Rayleigh number (Ra), 5 105 to 108, and the Prandtl number (Pr), 0:8 and 2. The octagon is constructed in such a way that it always inscribed in a square, with a xed horizontal length and varying slant lengths by

Accurate quantification of turbulent mixing induced by classical Rayleigh-Taylor instability is of fundamental importance for many natural phenomena and engineering applications. However, a systematic model to predict its evolution at different mixing levels and different density ratios (R) has not been established. In this paper, the mixing width is predicted by combining the principle of mass conservation

The proliferation of turbulence in subcritical wall-bounded shear flows involves spatially localised coherent structures. Turbulent spots correspond to finite-time nonlinear responses to pointwise disturbances and are regarded as seeds of turbulence during transition. The rapid spatial decay of the turbulent fluctuations away from a spot is accompanied by large-scale flows with a robust structuration

Particles suspended in a fluid exert feedback forces that can significantly impact the flow, altering the turbulent drag and velocity fluctuations. We study flow modulation induced by small spherical particles heavier than the carrier fluid in the framework of an Eulerian two-way coupled model, where particles are represented by a continuum density transported by a compressible velocity field, exchanging

The late stage of the freefall of homogeneous and heterogeneous cones in a quiescent water medium and the induced flow are experimentally inspected using there-dimensional particle tracking velocimetry and volumetric particle image velocimetry. The structures shared the same geometry but had different combined specific gravity SG∈[1.2,8]. Results showed four distinct freefall patterns, which were modulated

The effect of surfactants on the tail and film dynamics of elongated gas bubbles propagating through circular capillary tubes is investigated by means of an extensive three-dimensional numerical study using a hybrid front-tracking/level-set method. The focus is on the visco-inertial regime, which occurs when the Reynolds number of the flow is much larger than unity. Under these conditions, clean' bubbles

The addition of soluble long-chain polymers to a Newtonian fluid, and the incorporation of aerophilic textures on submerged solid boundaries, have both been successfully employed as independent, stand-alone methods for drag reduction in turbulent aqueous flows. In this work, we explore the possibility of combining the two strategies additively to obtain enhanced frictional drag reduction in wall-bounded

Active navigation relies on effectively extracting information from the surrounding environment, and often features the tracking of gradients of a relevant signal - such as the concentration of molecules. Microfluidic networks of closed pathways pose the challenge of determining the shortest exit pathway, which involves the proper local decision-making at each bifurcating junction. Here, we focus on

In this study, particle image velocimetry and electrochemical measurements were applied simultaneously to examine the relationship between wall shear stress and the three-component velocity field in pipe flow. Moreover, the large-scale motions in the velocity field were separated into very-large-scale motions (VLSMs) and large-scale motions (LSMs) to investigate their respective influences on the wall

Rotating fluids frequently show nonlinear wave interactions and turbulence. This is true in particular for non-uniformly rotating systems. One example of such a non-uniform rotating object is the Earth. Due to its fast rotation it is not exactly spherical. As a result of the interaction with the Sun and Moon the non-spherical Earth cannot rotate uniformly but shows precession and libration. This has

Euler-Lagrange point-particle simulation has emerged as a premier methodology for studying dispersed particle-laden flows. This method’s popularity stems from its ability to resolve fine-scale fluid structures while also tracking individual particles at reduced cost using an appropriate particle acceleration model. However, the point-particle model has known convergence issues in that refinement of

We consider the bypass transition in a flat plate boundary layer subject to free-stream turbulence and compute the evolution of the second-order structure function of the streamwise velocity, $du^2(,) $, from the laminar to the fully turbulent region using DNS. In order to separate the contributions from laminar and turbulent events at the two points used to define du(x⃗,r⃗), we apply conditional sampling

We investigate the local energy flux rate $\Pi_\ell(\bx)$ towards small scales in isotropic turbulent flows using direct numerical simulations and applying different low-pass filters. Two different filters are examined, a sharp Fourier filter and a Gaussian filter. The probability density function (pdf) of the local energy flux is calculated for the different filters and for different filtering scales