Interfaces and inhomogeneous turbulence

Hunt, J. C. R.; Eames, I.; Silva, Carlos B. da; Westerweel, J.

doi:10.1098/rsta.2010.0325

Cited by 35 publications

(27 citation statements)

References 71 publications

(111 reference statements)

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“…It should be noted that internal layers are not solely characterized by regions of intense shear; there may also be internal layers without significant shear. 2 Internal layers and the T/NT interface are shown to have similar characteristics and can be described by the same theoretical framework. By quantifying the entrainment over the bounding shear layers, growth rates of the associated large scale regions can be estimated, which is analogous to the overall TBL growth by the entrainment across the T/NT interface.…”

Section: Introductionmentioning

confidence: 92%

“…2,14 Recently, internal layers with similar characteristics as a T/NT interface within homogeneous isotropic turbulence were reported by Ishihara et al 5,6 According to Robinson 15 (and references therein), internal shear layers have been observed throughout TBLs as well, even in the outer region of the flow. For instance, Blackwelder and Kovasznay 16 showed that significant shear layers were observed upstream of large scale motions based on space-time correlations of hotwire data in a TBL.…”

Section: Introductionmentioning

confidence: 96%

“…Previous research has recognized the significance of these interfaces on the overall dynamics of the turbulent flow. [1][2][3][4][5][6][7][8][9] Knowledge on physical mechanisms occurring at these interfaces is especially important as a number of processes take place at or in close vicinity of the interface, e.g., it governs the overall growth of the turbulent flow region as entrainment of non-turbulent fluid into the turbulent flow occurs across this interface. Previous research on the turbulent/non-turbulent (T/NT) interface has focused on the definition of the interface and on the physical mechanism of entrainment at the interface.…”

Section: Introductionmentioning

confidence: 99%

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Interfaces and internal layers in a turbulent boundary layer

et al. 2015

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New experimental research is presented on the characteristics of interfaces and internal shear layers that are present in a turbulent boundary layer (TBL). The turbulent/non-turbulent (T/NT) interface at the outer boundary of the TBL shows the presence of a finite jump in streamwise velocity and is characterised by a thin shear layer. It appears that similar layers of high shear occur also within the TBL which separate regions of almost uniform momentum. It turns out that they exhibit similar characteristics as the external T/NT interface. Furthermore, the spatial growth rate of the TBL, that is derived from theoretical analysis, can be correctly predicted from a momentum balance near the external T/NT interface. Similarly, the entrainment velocities for the average internal layers have been determined. Results indicate that internal layers move slower in the vicinity of the wall, whereas they move faster than the large scale boundary layer growth rate in the outer region of the TBL. It is believed that shear layers bound large scale flow regions of approximately uniform momentum. Hence, the entrainment velocities of these internal layers may be interpreted as growth rates of the large scale motions in a TBL. C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Interfaces and internal layers in a turbulent boundary layer

et al. 2015

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“…Finally, following a successful Euromech 517 meeting on interfaces in turbulent flows, Hunt et al [8] describe a timely review of the presentations and a discussion of the broad outstanding questions in this area. The research community in this area is beginning to make significant inroads in this topic, as seen from the collection of papers in this Theme Issue.…”

Section: Organization Of Issuementioning

confidence: 99%

New developments in understanding interfacial processes in turbulent flows

Eames

Flór

2011

Phil. Trans. R. Soc. A.

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Interfaces, across which fluid and flow properties change significantly, are a ubiquitous feature of most turbulent flows and are present within jets, plumes, homogeneous turbulence, oceans and planetary atmospheres. Even when the interfaces occupy a small volume fraction of the entire flow, they largely control processes such as entrainment and dissipation and can act as barriers to transport. This Theme Issue brings together some of the leading recent developments on interfaces in turbulence, drawing in many methodologies, such as experiments, direct number simulations, inverse methods and analytical modelling.

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“…Dilution caused by entrainment at the edge of the jet or plume has been studied in detail over the last 50 years. Nevertheless, there is a debate on the detailed elements of entrainment, such as on the dominance of nibbling versus engulfment (Hunt, Eames & Westerweel 2006;Hunt et al 2011). Theoretical models on jets and plumes (List 1982) are usually based on the conceptual framework of Morton, Taylor & Turner (1956), which has been extended to include the effects of momentum, buoyancy and sources varying in time (Scase, Caulfield & Dalziel 2006a;Scase et al 2006b), non-Boussinesq behaviour (Woods 1997) and internal generation of buoyancy (Hunt & Kaye 2005).…”

Section: Introductionmentioning

confidence: 99%

Turbulent acidic jets and plumes injected into an alkaline environment

2013

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The characteristics of an acidic turbulent jet and plume injected into an alkaline environment are examined theoretically and experimentally. Fluid-flow and chemistry models are combined to understand how the concentration of acid in a parcel of fluid changes as it reacts with alkaline fluid entrained from the ambient. The resulting model is tested in an experimental study in which nitric acid jets or plumes are injected into a large tank containing a variety of alkaline substances. A video camera records a pH-sensitive dye in the jet or plume, which changes colour with variations in the pH. The results were time averaged and processed to measure distance from the source to the point of neutralization. The agreement between predictions and observations of neutralization distances is good, confirming that the model captures the salient physics of the problem. Using empirically determined titration curves, a combined fluid flow and chemistry model is applied to discuss the environmental implications of a warm acidic turbulent plume injected into an alkaline river or sea.

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Interfaces and inhomogeneous turbulence

Cited by 35 publications

References 71 publications

Interfaces and internal layers in a turbulent boundary layer

Interfaces and internal layers in a turbulent boundary layer

New developments in understanding interfacial processes in turbulent flows

Turbulent acidic jets and plumes injected into an alkaline environment

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