Polydisperse turbidity currents propagating over complex topography: Comparison of experimental and depth-resolved simulation results

Nasr-Azadani, Mohamad M.; Hall, Brendon; Meiburg, Eckart

doi:10.1016/j.cageo.2011.08.030

Cited by 51 publications

(45 citation statements)

References 42 publications

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“…Within its narrow range of validity between the vertical dotted lines, the model of [5] yields predictions in very close agreement with those of the other models, so that we do not show them in this figure. All four models predict that the minimum propagation velocity occurs at equilibrium conditions, which is consistent with the experimental observations of [7] and the present simulation results. Due to the finite -values employed in the DNS simulations, the DNS front velocity data generally fall slightly below the vorticity model predictions.…”

Section: Resultssupporting

confidence: 81%

“…Toward verifying the validity of the analytical solution, the results obtained by the above theory, were compared with the earlier theoretical and experimental data, as well as with the results of twodimensional and unsteady Direct Navier-Stokes Simulations (DNS) provided by the in-house code TURBINS, which has been described and validated in [6] and [7]. The dynamics of various types of intrusions introduced earlier in this paper, are captured in figure 2.…”

Section: Theory and Simulationsmentioning

confidence: 99%

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Intrusive gravity currents propagating into two-layer stratified ambients: Vorticity modeling

2016

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Section: Resultssupporting

confidence: 81%

Section: Theory and Simulationsmentioning

confidence: 99%

Intrusive gravity currents propagating into two-layer stratified ambients: Vorticity modeling

2016

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“…Numerical details and validation results of the code are provided in Nasr-Azadani & Meiburg (2011) and Nasr- Azadani et al (2013), so that we provide only a brief review here.…”

Section: Simulationsmentioning

confidence: 99%

Sustained gravity currents in a channel

et al. 2016

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Gravitationally-driven motion arising from a sustained constant source of dense fluid in a horizontal channel is investigated theoretically using shallow layer models and direct numerical simulations of the Navier-Stokes equations, coupled to an advectiondiffusion model of the density field. The influxed dense fluid forms a flowing layer underneath the less dense fluid, which initially filled the channel, and in this study its speed of propagation is calculated; the outflux is at the end of the channel. The motion, under the assumption of hydrostatic balance, is modelled using a two-layer shallowwater model to account for the flow of both the dense and the overlying less dense fluids. When the relative density difference between the fluids is small (the Boussinesq regime), the governing shallow layer equations are solved using analytical techniques. It is demonstrated that a variety of flow-field patterns is feasible, including those with constant height along the length of the current and contrasted with those where the height varies continuously and discontinuously. The type of solution realised in any scenario is determined by the magnitude of the dimensionless flux issued from the source and the source Froude number. Two important phenomena may occur: the flow may be choked, whereby the excess velocity due to the density difference is bounded and the height of the current may not exceed a determined maximum value, and it is also possible for the dense fluid to completely displace all of the less dense fluid originally in the channel in an expanding region close to the source. The onset and subsequent evolution of these types of motions are also calculated using analytical techniques. The same range of phenomena occurs for non-Boussinesq flows; in this scenario the solutions of the model are calculated numerically. The results of direct numerical simulations of the Navier-Stokes equations are also reported for unsteady two-dimensional flows in which there is inflow of dense fluid at one end of the channel and outflow at the other end. These simulations reveal the detailed mechanics of the motion and the bulk properties are compared with the predictions of the shallow-layer model to demonstrate good agreement between the two modelling strategies.

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“…Schematic of a shear layer overlying a stratified layer, in a turbidity current. This schematic is representative of a lock-exchange flow [Nasr-Azadani & Meiburg (2014); Nasr- Azadani et al (2013)], where a current of particle-laden water flows below a still layer of clear water. At early times the clear-turbid stratified interface coincides with the shear layer, but as time progresses, the particles sink, such that the stratified layer lies below the shear layer.…”

Section: Introductionmentioning

confidence: 99%

“…In geophysical situations, one often encounters such shear layers in proximity with stratified layers. Turbidity currents [Nasr-Azadani & Meiburg (2014); Nasr-Azadani et al (2013)] are a good example, a schematic of which is shown in figure 1. An underwater avalanche carrying particulate matter would cause such a current, where a fast flowing particle-laden layer lies below a relatively calm layer of clear water.…”

Section: Introductionmentioning

confidence: 99%

Instability of a free-shear layer in the vicinity of a viscosity-stratified layer

Sahu

Govindarajan

2014

J. Fluid Mech.

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The stability of a mixing layer made up of two miscible fluids, with a viscosity-stratified layer between them, is studied. The two fluids are of the same density. It is shown that unlike other viscosity stratified shear flows, where species diffusivity is a dominant factor determining stability, species diffusivity variations over orders of magnitude do not change the answer to any noticeable degree in this case. Viscosity stratification, however, does matter, and can stabilize or destabilize the flow, depending on whether the layer of varying velocity is located within the less or more viscous fluid. By making an inviscid model flow with a slope change across the "viscosity" interface, we show that viscous and inviscid results are in qualitative agreement. The absolute instability of the flow can also be significantly altered by viscosity stratification.

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Polydisperse turbidity currents propagating over complex topography: Comparison of experimental and depth-resolved simulation results

Cited by 51 publications

References 42 publications

Intrusive gravity currents propagating into two-layer stratified ambients: Vorticity modeling

Intrusive gravity currents propagating into two-layer stratified ambients: Vorticity modeling

Sustained gravity currents in a channel

Instability of a free-shear layer in the vicinity of a viscosity-stratified layer

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