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Showing 1 to 15 of 15 for “"Buoyancy Frequency"”.
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The role of background flow variations in stratified flows over topography
… velocity and either a homogeneous or two-layer buoyancy-frequency profile. In this work, a numerical model is developed that accounts for general variations in the buoyancy-frequency profile far upstream and the presence of unsteadiness in the free-stream velocity. The model employs a …
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Theoretical and experimental study of nonlinear internal gravity wave beams
… internal gravity waves due to the effect of buoyancy. This type of wave motion is anisotropic since gravity provides a preferred direction. As a result, a localized source oscillating at a frequency below the buoyancy frequency in a uniformly stratified Boussinesq fluid, rather than …
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Measurements and models of fine-structure, internal gravity waves and wave breaking in the deep ocean
… Mode decay beyond the turning point in depth or frequency produces a sharp cutoff in vertical current spectra above the local buoyancy frequency N(z). An internal wave wavenumber-frequency spectral model Ε(α,ω) = E(ω/No)-2 (α./α0)-2 describes vertical current spectra and potential energy to …
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CFD Analyses of Flow Structures in Air-Ingress and Rod Bundle Problems
… For the air-ingress phenomenon, Brunt-Vaisala frequency, or buoyancy frequency, predicts a frequency of 2.34 Hz, which is confirmed by the dominant frequency of 2.4 Hz obtained from the wavelet analysis between times 1.2 s and 1.85 s. For the rod bundle study, the dominant frequency at the …
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A sphere settling in a stratified fluid at small Reynolds number
… draws lighter fluid downwards, generating buoyancy forces: this results in a long density wake, extending many particle diameters downstream. Using time-lapse photography, the drag on the sphere was measured and we have obtained the first experimental quantification of the added drag on a …
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A laboratory study of localized boundary mixing in a rotating stratified fluid
… thickness ... is independent of the Coriolis frequency f. N is the buoyancy frequency, co is the bar frequency, and the constant, Y=1 cm, is empirically determined by bar mechanics. In initial experiments, the bar is exposed on three sides. Mixed fluid intrudes directly into the interior as a …
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Laboratory experiments of multi-phase plumes in stratification and crossflow
… using a micrometer. Slip velocities among all buoyancy sources ranged from 3 to 35 cm/s. Stratified experiments investigated the dependence of plume properties on the nondimensional slip velocity, UN= us/(BN)1/4 , where u, is the slip velocity, B is the total kinematic buoyancy flux, and N is …
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Interpretation of equatorial current meter data as internal waves
… and Munk use linear dynamics to synthesize frequency-wavenumber energy spectra for internal waves (GM72, GM75, GM79). The GM internal wave models are horizontally isotropic, vertically symmetric, purely propagating, and universal in both time and space. This set of properties effectively …
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Turbulent mixing in stratified fluids : layer formation and energetics
… where U is the speed of the rod and Ni is the buoyancy frequency of the initial profile. The functional relationship is ls = 2.6U / Ni + l.Ocm. For Rio < Ric, the mixing efficiency, Rf, monotonically decreases to the end of a run. However, for Rio > Ric, the evolution of Rf is closely related …
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Magneto-thermal Instability in Dilute Magnetized Plasmas
… thermal diffusivity, temperature gradient, and buoyancy frequency. We then show that our scaling laws are consistent with extant observations of ICM turbulence if the thermal conductivity is reduced by a factor of about ten from its Spitzer value. In the second part of the thesis, we begin to …
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On convective penetration of a buoyant plume into a stably stratified layer
… using a representation of the plume in buoyancy-tracer phase space to consider the mixing in more detail than has previously been achieved. We develop a new method for objectively partitioning plume fluid in buoyancy-tracer space into three regions, each of which corresponds to a …
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Eddy forcing of the mean circulation in the western North Atlantic
… the problem of determining the effect of the low-frequency eddy variability on the mean circulation of the Western North Atlantic. A framework for this study is first established by scale analysis of the eddy and mean terms in the mean momentum, vorticity, and heat balances in three regions of the …
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Mixing in stably stratified turbulent flows: improved parameterizations of diapycnal mixing in oceanic flows
… kinetic energy, N = √(-g/ρ)(∂ρ/∂z) is the buoyancy frequency of the background stratification, ρ is the density, Γ = Rƒ/(1 - Rƒ) is a mixing coefficient and Rƒ is the mixing efficiency, that is widely (but questionably) assumed to be constant or sometimes parameterized. However, a robust …
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Observations of turbulence, internal waves and background flows : an inquiry into the relationships between scales of motion
… flow were examined to address the issue of the buoyancy scaling of ε. These data exhibited large variations in background stratification with depth, but the internal wave characteristics were not substantially differentiable from the GM prescription. The magnitude of ε and its functional …