Kinetic energy in grid turbulence: comparison between data and theory

Janzen, Johannes Gérson; Souza, Leonardo Barra Santana de; Schulz, Harry Edmar

doi:10.1590/s1678-58782003000400006

Cited by 6 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such a device was used by Cook (1973), Ivanov (1973), Cook (1978), Roach (1987, Zwart, Budwig, and Tavoularis (1997), Janzen, de Souza and Schulz (2003), Lang and Gomez (2004) and Schulz, Janzen and de Souza (2006) to generate turbulence. According to Castro, Marighetti, De Bortoli and Natalini (2003) a grid promotes an improved homogeneity of a velocity profile and produces higher turbulence intensity.…”

Section: Introductionmentioning

confidence: 99%

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

Jaeger¹,

Meneses

Knorr³

2009

Innovative Food Science & Emerging Technologies

111

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

Jaeger¹,

Meneses

Knorr³

2009

Innovative Food Science & Emerging Technologies

111

View full text Add to dashboard Cite

“…They are considered as of the same order of magnitude than the size of the largest flocs (Bouyer et al 2004, Mietta et al 2009. Average Kolmogorov microscale (η) corresponding to turbulent kinetic energy (TKE) generated by grid oscillations of 3 and 12 s period were 272 and 1021 µm, respectively (Matsunaga et al 1999, Jansen et al 2003, which was close to those measured in Cam estuary during dry season of 2009 for mid ebb and slack water; 256 and 950 µm, respectively.…”

Section: Oscillating-grid Turbulence (Ogt)mentioning

confidence: 58%

The Role of Tep in Estuarine Hydrosedimentary Functioning: Impact on Settling Velocity of Aggregates

Lefèbvre¹,

Mari²,

Thao

et al. 2014

Int. Conf. Coastal. Eng.

View full text Add to dashboard Cite

Transparent exopolymer particles (TEP) are widely recognized to promote sediment aggregation in eutrophic environments. Flocculation in presence of TEP of various suspended sediment concentrations of material sampled on the bank of the Cam River was quantified at the laboratory for turbulence level consistent with slack water and mid ebb conditions measured in the Cam River estuary during dry season of 2009. Stickiness and concentrations of TEP were let to naturally fluctuate by incubation (aging in the dark) for up to nine days. We found that the impact of turbulence on overall buoyancy of TEP-governed aggregation was always opposite between slack water and mid ebb conditions for any duration of incubation; always negative for slack water conditions but for 126 hours of incubation and significantly negative for mid ebb conditions but for 126 hours of incubation. Suspended sediment concentration (SSC) consistently limited aggregates buoyancy, negative or positive. We propose a conceptual model that relates measured and inferred parameters to observed hydrosedimentary processes.

show abstract

“…De Silva and Fernando (1998) used an OGT to simulate turbulence patches and associated mixing in a linearly stratified fluid as found in oceans. The apparatus also has been used to study the physics of turbulence and its comparison to theory (De Silva and Fernando 1994;Villermaux et al 1995;Matsunaga et al 1999;Cheng and Law 2001;Janzen et al 2003;Schulz et al 2006;Wan Mohtar 2016). Huppert et al (1995) used a mixing box to examine sediment entrainment in a dense suspension layer stirred by an oscillating grid.…”

Section: Introductionmentioning

confidence: 99%

Secondary circulation within a mixing box and its effect on turbulence

2020

View full text Add to dashboard Cite

An experimental study was conducted to examine the formation of secondary circulation in a grid-mixing box and to determine its effect on turbulence. This apparatus has been used extensively to study turbulence and mixing in a variety of geophysical contexts, and it is commonly assumed that turbulence is nearly isotropic and horizontally homogenous and that it is a zero-mean shear flow. Exceptions to these assumptions, however, have been reported, where a secondary flow pattern has been observed consisting of two roughly symmetric large-scale circulations with upward flow in the center of the box and downward return flow along the sides. These secondary flows appear to be associated with different grid oscillation conditions and box and grid geometries, and criteria have been proposed to describe conditions when secondary flow may be expected. Experiments were conducted for three different combinations of the grid oscillation stroke and frequency, while maintaining a near constant grid Reynolds number, to examine the formation and strength of the secondary flow and its effect on the magnitude and distribution of turbulence within the box. Velocity characteristics were obtained by particle image velocimetry (PIV). Results show that (1) secondary circulations were present for all combinations of the grid oscillation conditions; (2) as stroke length increased, the intensity of the secondary circulation and the contribution of these motions to total kinetic energy increased; and (3) the presence of secondary circulation results in greater overall mixing and turbulent transport in the region close to the grid. These insights are expected to be relevant to a wide range of mixing box applications.

show abstract

Kinetic energy in grid turbulence: comparison between data and theory

Cited by 6 publications

References 15 publications

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

The Role of Tep in Estuarine Hydrosedimentary Functioning: Impact on Settling Velocity of Aggregates

Secondary circulation within a mixing box and its effect on turbulence

Contact Info

Product

Resources

About