CARTUM: Comparative analysis and realization of second-moment turbulence models

• Research unit: EU RFP
• Project number: 98.0169-2

Key words (English)

TURBULENCE; LARGE EDDY SIMULATIONS; MICROSTRUCTURE MEASUREMENTS

Alternative project number (English)

EU project number: MAS3-CT98-0172

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.2 Marine sciences and technologies

Short description (English)

See abstract

Partners and International Organizations (English)

Coordinator: Universität Hamburg (D)

Abstract (English)

Johannes Sander, University, Bern, T. Jonas, A. Simon, A. Wüest, EAWAG, Zürich
An attempt to assess the quality of large eddy simulations of the mixed layer of a lake during strong convective events is made. We compare results from microstructure measurements of the temperature with simulations. For that, we obtain the rate of dissipation of turbulent kinetic energy and of temperature variance from the observations and from the calculations. Vertical profiles of the rate of dissipation of turbulent kinetic energy show excellent aggreement of observed with simulated results. For dissipation of temperature variance, large eddy simulation produce much smaller rates than have been observed in the lake.
In a second approach scaling laws are obtained with a statistical analyses of deep reaching convection from results with large eddy simulations. The study focuses a rotating fluid which is initially neutrally stratified. With dimensional analyses it is shown, that only the temperature gradient is modified by the rate of rotation while other variables, like velocities, eddy viscosity or rate of dissipation do not show a statistically robust influence of rotation. These behaviour is very different from results obtained from stratified fluids.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
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Swiss Project-Number: 98.0169-2