A turbulent diffusion model of Rayleigh-Taylor mixing
| Autor: | Martin G. Plys, Michael Epstein, Chan Y. Paik, Sung Jin Lee |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Turbulent diffusion Turbulence Mechanics Thermal diffusivity Similarity solution 01 natural sciences Instability 010305 fluids & plasmas Physics::Fluid Dynamics Nuclear Energy and Engineering Dispersion relation 0103 physical sciences 010306 general physics Mixing (physics) Dimensionless quantity |
| Zdroj: | Annals of Nuclear Energy. 116:290-295 |
| ISSN: | 0306-4549 |
| DOI: | 10.1016/j.anucene.2018.02.042 |
| Popis: | A simple turbulent diffusion model is described for predicting late term mixing due to Rayleigh-Taylor instability at an interface that initially separates two semi-infinite regions of fluid of different densities. The one-dimensional, transient species conservation equation is combined with an available vertical dispersion equation which relates the turbulent diffusivity to the local density gradient and a characteristic mixing length. The similarity solution of the species conservation equation yields the well-known long time result for the vertical extent of the mixing region and shows that the dimensionless growth constant that appears in the mixing thickness equation is simply a measure of the size of the characteristic mixing length. A simple polynomial relation is derived for the heavy fluid volume fraction profile within the mixing region which is in close agreement with the profile obtained from a previously reported numerical simulation of Rayleigh-Taylor mixing. It is demonstrated how the model can be readily applied to predict Rayleigh-Taylor mixing in a finite fluid region between top and bottom boundaries. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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