Algebraic Turbulence Model for Stratified Tidal Flows

Lehfeldt, Rainer; Bloss, Siegfried

doi:10.1007/978-3-642-73691-9_15

Cited by 23 publications

(10 citation statements)

References 15 publications

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“…In a well-mixed water column the Reynolds analogy is quite reasonable, but it is no longer valid in the presence of stable density stratification (Turner 1973) Stable stratification decreases turbulent mixing in general, but mixing of mass decreases more than mixing of momentum such that K, can be significantly smaller than KAl (e.g. Abraham 1988, Lehfeldt & Bloss 1988, Chao & Paluszkiewicz 1991.…”

Section: Turbulent Mixingmentioning

confidence: 99%

Turbulent mixing in experimental ecosystem studies

Sanford¹

1997

Mar. Ecol. Prog. Ser.

122

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ABSTRACT. Turbulent mixing is an integral aspect of aquatic ecosystems Turbulence affects ecosystem features ranglng from phytoplankton blooms at large scales through microscale interactions in the plankton. Enclosed experimental ecosystems, if they are to mimic the function of natural ecosystems, also must mimic natural turbulence and its effects. Large-scale velocity gradients and unstable buoyancy fluxes generate turbulent mixing in nature, most often at the surface and bottom boundaries and in the pycnocline. Large eddy sizes are controlled by the mixed layer depth, boundary layer thickness, or overturning length in the pycnocl~ne. Turbulent energy cascades through smaller and smaller eddy scales until it can be dissipated by molecular viscosity at the smallest scales. In contrast, artificial apparatuses frequently are used to generate turbulent m~x i n g in the interior of experimental ecosystem enclosures Large eddy sizes are controlled by the size of the generation apparatus, and they usually are much smaller than in nature Mismatched large eddy length scales and differences in turbulence generation mechanisms are responsible for the difficulties in mimicking natural turbulent mixing in experimental enclosures. The 2 most important turbulence parameters to consider in experimental ecosystem research are overall mixing time, T,,,, and turbulence dissipation rate, E. If the levels, spatial dlstribut~ons, and temporal variability of T,,, and E can be matched between an enclosure and the natural system it IS to model, then potential mixing artifacts can be minimized. An important additional consideration is that benthic ecosystems depend on the time-averaged boundary layer flow a s much as the turbulence. Existing designs for m i x~n g experimental ecosystems are capable of reasonably representing some aspects of natural turbulent mixing Paddle and grid stirring are the best available techniques for water column mixing, and flumes are best for benthic turbulence. There is no design at present that represents both environments adequately. More work also is needed on mixing of flexiblewall in situ enclosures. A more serious problem, however, is that turbulent mixing in experimental ecos)~stem studies too often is ignored, inadequately characterized, or unreported. Several methods are available for reasonable characterlzation of mixing in enclosures without sophisticated technology, and the technology for direct velocity measurements is becoming more accessible. Experimental ecosystem researchers should make a concerted effort to implement, characterize, and report on turbulent mixing In t h e~r enclosures.

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Section: Turbulent Mixingmentioning

confidence: 99%

Turbulent mixing in experimental ecosystem studies

Sanford¹

1997

Mar. Ecol. Prog. Ser.

122

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“…where m and h are stability functions (functions of the Richardson number, R i ), l is a scale length (e.g., Lehfeldt and Bloss, 1988) and q the turbulent speed:…”

Section: Eddy Viscosities and Diffusivitiesmentioning

confidence: 99%

Modeling of Estuarine and Coastal Waters

Torres

Uncles

2011

Treatise on Estuarine and Coastal Science

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“…For these experiments an assumption was made that in the upper tidal Delaware River, the circulation effects of a model run without sources of salt at the end members would be negligible, since the normal salinity in the area of interest is on the order of 0.02 psu. MARINA's numerical solution of the governing equations includes the equation of state for density based on Lehfeldt and Bloss (1988),…”

Section: Dispersive Transport Processesmentioning

confidence: 99%

Cross-Channel Transport in the Upper Delaware Estuary: Numerical Experiments for Contamination Vulnerability Assessment

Duzinski¹,

Stammermann²

2010

Estuarine and Coastal Modeling (2009)

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fluids, the pressure field is related only to the density field; i.e., constant pressure surfaces are parallel to constant density surfaces. In contrast, constant pressure surfaces do not coincide with constant density surfaces in a baroclinic fluid, and, for example, circulation may result from a vertical salinity or thermal gradient. * Phase referenced to Local Standard Time. ** Station C54 only had 19.9 days of data, less than the 29 days required to derive the N2 constituent

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Algebraic Turbulence Model for Stratified Tidal Flows

Cited by 23 publications

References 15 publications

Turbulent mixing in experimental ecosystem studies

Turbulent mixing in experimental ecosystem studies

Modeling of Estuarine and Coastal Waters

Cross-Channel Transport in the Upper Delaware Estuary: Numerical Experiments for Contamination Vulnerability Assessment

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