Premium
Double‐diffusive interfaces in Lake Kivu reproduced by direct numerical simulations
Author(s) -
Sommer Tobias,
Carpenter Jeffrey R.,
Wüest Alfred
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl060716
Subject(s) - homogeneous , microstructure , diffusion , flux (metallurgy) , temperature gradient , direct numerical simulation , materials science , mechanics , heat flux , thermodynamics , physics , computational physics , meteorology , heat transfer , turbulence , composite material , reynolds number , metallurgy
Double diffusion transforms uniform background gradients of temperature and salinity into “staircases” of homogeneous mixed layers that are separated by high‐gradient interfaces. Direct numerical simulations (DNS) and microstructure measurements are two independent methods of estimating double‐diffusive fluxes. By performing DNS under similar conditions as found in our measurements in Lake Kivu, we are able to compare results from both methods for the first time. We find that (i) the DNS reproduces the measured interface thicknesses of in situ microstructure profiles, (ii) molecular heat fluxes through interfaces capture the total vertical heat fluxes for density ratios larger than three, and (iii) the commonly used heat flux parameterization underestimates the total fluxes by a factor of 1.3 to 2.2.