A velocity-biased turbulent mixing model for passive scalars in homogeneous turbulence

1987 ◽  
Vol 30 (7) ◽  
pp. 2046 ◽  
Author(s):  
J. C. Song
Keyword(s):  
Turbulent Mixing ◽  
Mixing Model ◽  
Homogeneous Turbulence ◽  
Passive Scalars

scholarly journals Multifractal analysis of oceanic chlorophyll maps remotely sensed from space

Ocean Science ◽  
2011 ◽  
Vol 7 (2) ◽  
pp. 219-229 ◽  
Author(s):  
L. de Montera ◽  
M. Jouini ◽  
S. Verrier ◽  
S. Thiria ◽  
M. Crepon
Keyword(s):  
Turbulent Mixing ◽  
Multifractal Analysis ◽  
Numerical Models ◽  
Specific Region ◽  
Dominant Effect ◽  
Passive Scalars ◽  
Analysis Techniques ◽  
Low Cloud ◽  
Scale Range ◽  
Low Cloud Cover

Abstract. Phytoplankton patchiness has been investigated with multifractal analysis techniques. We analyzed oceanic chlorophyll maps, measured by the SeaWiFS orbiting sensor, which are considered to be good proxies for phytoplankton. The study area is the Senegalo-Mauritanian upwelling region, because it has a low cloud cover and high chlorophyll concentrations. Multifractal properties are observed, from the sub-mesoscale up to the mesoscale, and are found to be consistent with the Corssin-Obukhov scale law of passive scalars. This result indicates that, in this specific region and within this scale range, turbulent mixing would be the dominant effect leading to the observed variability of phytoplankton fields. Finally, it is shown that multifractal patchiness can be responsible for significant biases in the nonlinear source and sink terms involved in biogeochemical numerical models.

A DNS study of turbulent mixing of two passive scalars

1996 ◽  
Vol 8 (8) ◽  
pp. 2161-2184 ◽  
Author(s):  
A. Juneja ◽  
S. B. Pope
Keyword(s):  
Turbulent Mixing ◽  
Passive Scalars

scholarly journals Multifractal analysis of oceanic chlorophyll maps remotely sensed from space

2011 ◽  
Vol 8 (1) ◽  
pp. 55-84
Author(s):  
L. de Montera ◽  
M. Jouini ◽  
S. Verrier ◽  
S. Thiria ◽  
M. Crepon
Keyword(s):  
Turbulent Mixing ◽  
Multifractal Analysis ◽  
Numerical Models ◽  
Remotely Sensed ◽  
Dominant Effect ◽  
Passive Scalars ◽  
Nonlinear Source ◽  
Analysis Techniques ◽  
Scale Range ◽  
Source And Sink

Abstract. Phytoplankton patchiness has been investigated with multifractal analysis techniques. We analyzed oceanic chlorophyll maps, measured by the SeaWiFS orbiting sensor, which are considered to be good proxies for phytoplankton. Multifractal properties are observed, from the sub-mesoscale up to the mesoscale, and are found to be consistent with the Corssin-Obukhov scale law of passive scalars. This result indicates that, within this scale range, turbulent mixing would be the dominant effect leading to the observed variability of phytoplankton fields. Finally, it is shown that multifractal patchiness can be responsible for significant biases in the nonlinear source and sink terms involved in biogeochemical numerical models.

A strategy for large-scale scalar advection in large eddy simulations that use the linear eddy sub-grid mixing model

2018 ◽  
Vol 28 (10) ◽  
pp. 2463-2479 ◽  
Author(s):  
Salman Arshad ◽  
Bo Kong ◽  
Alan Kerstein ◽  
Michael Oevermann
Keyword(s):  
Turbulent Mixing ◽  
Large Scale ◽  
Molecular Diffusion ◽  
Passive Scalar ◽  
Mixing Model ◽  
Large Eddy Simulations ◽  
High Flux ◽  
Scalar Mixing ◽  
Content Type ◽  
Large Eddy

PurposeThe purpose of this numerical work is to present and test a new approach for large-scale scalar advection (splicing) in large eddy simulations (LES) that use the linear eddy sub-grid mixing model (LEM) called the LES-LEM.Design/methodology/approachThe new splicing strategy is based on an ordered flux of spliced LEM segments. The principle is that low-flux segments have less momentum than high-flux segments and, therefore, are displaced less than high-flux segments. This strategy affects the order of both inflowing and outflowing LEM segments of an LES cell. The new splicing approach is implemented in a pressure-based fluid solver and tested by simulation of passive scalar transport in a co-flowing turbulent rectangular jet, instead of combustion simulation, to perform an isolated investigation of splicing. Comparison of the new splicing with a previous splicing approach is also done.FindingsThe simulation results show that the velocity statistics and passive scalar mixing are correctly predicted using the new splicing approach for the LES-LEM. It is argued that modeling of large-scale advection in the LES-LEM via splicing is reasonable, and the new splicing approach potentially captures the physics better than the old approach. The standard LES sub-grid mixing models do not represent turbulent mixing in a proper way because they do not adequately represent molecular diffusion processes and counter gradient effects. Scalar mixing in turbulent flow consists of two different processes, i.e. turbulent mixing that increases the interface between unmixed species and molecular diffusion. It is crucial to model these two processes individually at their respective time scales. The LEM explicitly includes both of these processes and has been used successfully as a sub-grid scalar mixing model (McMurtry et al., 1992; Sone and Menon, 2003). Here, the turbulent mixing capabilities of the LES-LEM with a modified splicing treatment are examined.Originality/valueThe splicing strategy proposed for the LES-LEM is original and has not been investigated before. Also, it is the first LES-LEM implementation using unstructured grids.

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