We propose a quantitative criterion for the merging of pair equal two-dimensional co-rotating vortices. A cross-validation between experimental and theoretical analyses is performed. Experimental vortices are generated by roll-up vortex sheet originating from identical impulsive rotation two plates. The phenomenon then followed up in time until rapid pairing transition occurs which critical parameters measured. In approach, nonlinear Euler solution representing computed various nonuniform...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPressure-volume-temperature behavior of difluoromethaneP. F. Malbrunot, P. A. Meunier, Georges M. Scatena, Whitney H. Mears, Kevin Paul. Murphy, and Joseph V. SinkaCite this: J. Chem. Eng. Data 1968, 13, 1, 16–21Publication Date (Print):January 1968Publication History Published online1 May 2002Published inissue 1 January 1968https://pubs.acs.org/doi/10.1021/je60036a006https://doi.org/10.1021/je60036a006research-articleACS PublicationsRequest reuse...

In this paper, the instability of a fluid inside precessing cylinder is addressed theoretically and experimentally. The precessional motion forces Kelvin modes in cylinder, which can become resonant for given frequencies aspect ratios. When Reynolds number large enough, these forced eventually unstable. A linear stability analysis based on triadic resonance between mode two additional free carried out. This allows us to predict spatial structure its threshold. These predictions are compared...

This paper presents experimental and theoretical results on the internal waves emitted by a bluff body moving horizontally in linearly stratified fluid. Three different bodies (a sphere, spheroid cylinder) have been used order to study effect of shape body, although most are obtained for sphere. Two types observed experimentally: large wavelength lee generated itself small coherent wake turbulent wake. First, separated from averaging measurements frame with body. The velocity amplitude...

The interaction of two parallel vortices equal circulation is observed experimentally. For low Reynolds numbers (Re), the remain dimensional and merge into a single one, when their time-dependent core size exceeds approximately 30% vortex separation distance. At higher Re, three-dimensional (3-D) instability discovered, showing characteristics an elliptic cores. rapidly generates small-scale turbulent motion, which initiates merging for smaller sizes produces bigger final than laminar 2-D flow.

In this paper, we report experimental results concerning a three-dimensional short-wave instability observed in pair of equal co-rotating vortices. The is generated water by impulsively started plates, and analysed through dye visualizations detailed quantitative measurements using particle image velocimetry. mode, which found to be stationary the rotating frame reference two-vortex system, consists internal deformations vortex cores, are characteristic elliptic occurring strained vortical...

In this paper, we report experimental and theoretical results on the flow inside a precessing rotating cylinder. Particle image velocimetry measurements have revealed instantaneous structure of confirmed that it is sum forced inertial (Kelvin) modes, as predicted by classical linear inviscid theory. But theory predicts also amplitude mode diverges when its natural frequency equals precession frequency. A viscous weakly nonlinear has therefore been developed at resonance. This compared to...

In the context of CO${}_{2}$ geological storage in deep saline aquifers, convective dissolution porous media has been subject theory and numerical studies at Darcy scale. By using both refractive index matching planar laser induced fluorescence, we measure onset characteristics (growth rate, wavelength, flux) instability a three-dimensional granular medium located below gas compartment. The obtained results show large discrepancies with theoretical predictions based on scale models but are...

This paper presents experimental results on the wake of a propelled bluff body towed at constant horizontal speed in linearly stratified fluid. Three regimes have been found, depending angle attack and ratio drag force to propeller thrust. Most experiments were obtained first regime where strong momentum flux is created wake, which can be oriented backward or forward thrust propeller. The velocity amplitude, width Strouhal number predicted by defining thickness based coefficient A second for...

Direct numerical simulations of flows in cylinders subjected to both rapid rotation and axial precession are presented analysed the context a stability theory based on triadic resonance Kelvin modes. For case that was chosen provide finely tuned resonant instability with small nutation angle, good agreement previous experiments terms mode shapes dynamics, including long-time-scale regularization flow recurrent collapses. Cases not most unstable triad, but angle still small, also quite...

A technique for simultaneous measurement of the displacement field evaporating droplets in a spray and their vapor shows that dense spatial dispersion passively advected slaved to dynamics its saturating field, can be described as scalar mixing problem.

The existence of a new regime in convective instabilities when the wavelength instability becomes smaller than pore size is demonstrated. A theory, adapted from classical linear stability analyses, accompanies experimental characterizations regime.

A general model is described for drag wakes in a linearly stratified fluid, based on the self-preservation of flow. It assumed that buoyancy-controlled self-similar wake expands horizontal direction due to turbulent diffusion and vertical viscous diffusion. The mean characteristics (height, width velocity defect) are analytically derived show good agreement with existing data from experimental numerical results. Moreover, three regimes previously found literature characterize different...

Convective dissolution is the process by which CO2 injected in geological formations dissolves into aqueous phase and thus remains stored perennially gravity. It can be modeled buoyancy-coupled Darcy flow solute transport. The transport equation should include a diffusive term accounting for hydrodynamic dispersion, wherein effective diffusion coefficient proportional to local interstitial velocity. We investigate impact of dispersion tensor on convective two-dimensional (2D)...

Convective dissolution, one of the main mechanisms for geological storage ${\mathrm{CO}}_{2}$, occurs when supercritical or gas ${\mathrm{CO}}_{2}$ dissolves partially into an aqueous solution, thus triggering downward convection denser ${\mathrm{CO}}_{2}$-enriched liquid. Chemical reaction in liquid can greatly enhance process. Here, experimental measurements convective flow inside a cylinder filled with sodium hydroxide (NaOH) solution show that plume's velocity be increased tenfold as...

The structure of a columnar vortex in stably stratified fluid is studied experimentally and theoretically when the axis slightly tilted with respect to direction stratification. When Froude number larger than 1, we show that tilting induces strong density variations an intense axial flow rim around vortex. We demonstrate these characteristics can be associated critical-point singularity correction azimuthal wavenumber m = 1 generated by where angular velocity equals Brunt–Väisälä frequency...

The tilt-over mode in a precessing triaxial ellipsoid is studied theoretically and numerically. Inviscid viscous analytical models previously developed for the spheroidal geometry by Poincaré [Bull. Astron. 27, 321 (1910)] Busse [J. Fluid Mech. 33, 739 (1968)] are extended to this more complex geometry, which corresponds tidally deformed spinning astrophysical body. As confirmed three-dimensional numerical simulations, proposed model provides an accurate description of stationary flow...

Contained rotating flows subject to precessional forcing are well known exhibit rapid and energetic transitions disorder. Triadic resonance of inertial modes has been previously proposed as an instability mechanism in such flows, that idea was developed into a successful model for predicting cylindrical container when departures from solid-body rotation sufficiently small. Using direct numerical simulation dynamic mode decomposition, we analyse instabilities precessing cylinder whose...

Abstract

The advection–diffusion of a small surface element scalar in three dimensions (or line two dimensions) is solved analytically thanks to the Ranz transform (Ranz, AIChE J. , vol. 25, issue 1, 1979, pp. 41–47). As quantum or elementary brick any complex mixture, we call this diffuselet. Its evolution computed numerically from integration velocity gradient along trajectory, as classically done for Lyapunov exponents. concentration profile across diffuselet obtained product its initial...

In this paper we compare the wakes of various bluff bodies in a stratified fluid at moderately high Froude numbers (F≡2UB/ND>8) and Reynolds (Re≈5000). The size amplitude long-lasting clearly depend on shape body, wake width being small for streamlined object large an with sharp edges. However, can be collapsed when it is normalized by effective diameter based drag force, often called momentum thickness. General laws width, velocity defect, Strouhal number are thus deduced fit data...

In this work, we analyse the linear stability of a frozen Lamb–Oseen vortex in fluid linearly stratified along axis. The temporal properties three-dimensional normal modes are obtained under Boussinesq approximation with Chebychev collocation spectral code for large ranges Froude numbers and Reynolds (the Schmidt number being fixed to 700). A specific integration technique complex plane is used order apply condition radiation at infinity. For small numbers, show that unstable respect all...

The stability of the flow around a rotating cylinder in fluid linearly stratified along axis is studied numerically and experimentally for moderate Reynolds numbers. assumed potential axisymmetric with an angular velocity profile Ω = 1/ r 2 , where radial coordinate. Neglecting density diffusion non-Boussinesq effects, properties linear normal modes are first provided. A comprehensive diagram then obtained Froude numbers between 0 3 below 1000. main result that flow, which stable homogeneous...