NASA Technical Reports Server (NTRS) 20110016811: Part 1 of a Compu... | |
by NASA Technical Reports Server (NTRS) | |
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This first of three reports on a computational study of a | |
drop-laden temporal mixing layer presents the results of | |
direct numerical simulations (DNS) of well-resolved flow | |
fields and the derivation of the large-eddy simulation | |
(LES) equations that would govern the larger scales of a | |
turbulent flow field. The mixing layer consisted of two | |
counterflowing gas streams, one of which was initially | |
laden with evaporating liquid drops. The gas phase was | |
composed of two perfect gas species, the carrier gas and | |
the vapor emanating from the drops, and was computed in | |
an Eulerian reference frame, whereas each drop was | |
tracked individually in a Lagrangian manner. The flow | |
perturbations that were initially imposed on the layer | |
caused mixing and eventual transition to turbulence. The | |
DNS database obtained included transitional states for | |
layers with various liquid mass loadings. For the DNS, | |
the gas-phase equations were the compressible Navier- | |
Stokes equations for conservation of momentum and | |
additional conservation equations for total energy and | |
species mass. These equations included source terms | |
representing the effect of the drops on the mass, | |
momentum, and energy of the gas phase. From the DNS | |
equations, the expression for the irreversible entropy | |
production (dissipation) was derived and used to | |
determine the dissipation due to the source terms. The | |
LES equations were derived by spatially filtering the DNS | |
set and the magnitudes of the terms were computed at | |
transitional states, leading to a hierarchy of terms to | |
guide simplification of the LES equations. It was | |
concluded that effort should be devoted to the accurate | |
modeling of both the subgridscale fluxes and the filtered | |
source terms, which were the dominant unclosed terms | |
appearing in the LES equations. | |
Date Published: 2016-10-23 07:48:56 | |
Identifier: NASA_NTRS_Archive_20110016811 | |
Item Size: 1629415 | |
Language: english | |
Media Type: texts | |
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