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| Titel |
Verification and calibration of Energy- and Flux-Budget (EFB) turbulence closure model through large eddy simulations and direct numerical simulations |
| VerfasserIn |
Evgeny Kadantsev, Carl Fortelius, Oleg Druzhinin, Evgeny Mortikov, Andrey Glazunov, Sergej Zilitinkevich |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122461
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| Publikation (Nr.) |
 EGU/EGU2016-1502.pdf |
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| Zusammenfassung |
| We examine and validate the EFB turbulence closure model (Zilitinkevich et al., 2013),
which is based on the budget equations for basic second moments, namely, two energies:
turbulent kinetic energy EK and turbulent potential energy EP, and vertical turbulent fluxes
of momentum and potential temperature, τi (i = 1, 2) and Fz. Instead of traditional
postulation of down-gradient turbulent transport, the EFB closure determines the eddy
viscosity and eddy conductivity from the steady-state version of the budget equations for
τi and Fz. Furthermore, the EFB closure involves new prognostic equation for
turbulent dissipation time scale tT, and extends the theory to non-steady turbulence
regimes accounting for non-gradient and non-local turbulent transports (when the
traditional concepts of eddy viscosity and eddy conductivity become generally
inconsistent).
Our special interest is in asymptotic behavior of the EFB closure in strongly stable
stratification. For this purpose, we consider plane Couette flow, namely, the flow
between two infinite parallel plates, one of which is moving relative to another.
We use a set of Direct Numerical Simulation (DNS) experiments at the highest
possible Reynolds numbers for different bulk Richardson numbers (Druzhinin et al.,
2015).
To demonstrate potential improvements in Numerical Weather Prediction models, we test
the new closure model in various idealized cases, varying stratification from the neutral
and conventionally neutral to stable (GABLS1) running a test RANS model and
HARMONIE/AROME model in single-column mode. Results are compared with DNS and
LES (Large Eddy Simulation) runs and different numerical weather prediction models. |
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