Measurements of entrainment and mixing in turbulent jets

Dahm, Werner J. A.; Dimotakis, Paul E.

doi:10.2514/3.9770

Cited by 218 publications

(97 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(1983) at Re=650, 2,500 and 10,000, and by Dahm and Dimotakis (1987) at Re = 1,500, 5,000 and 10,000. In both studies, a movie sequence of planar visualizations along the centerline of a jet flow together with space-time (x-t) diagrams were used to show organized motion.…”

Section: Introductionmentioning

confidence: 99%

Large-scale dynamics in high Reynolds number jets and jet flames

Mungal

Lozano

Cruyningen

1992

Experiments in Fluids

View full text Add to dashboard Cite

The far-field large-scale dynamics of a momentum-driven Re = 2 • 108 non-reacting jet and a Re = 3 • 107 jet diffusion flame are presented and compared. The results are derived from computer graphic volume rendering of a set of sequential images of each flow. When compared to conventional display techniques, volume rendering, by allowing many frames of a movie sequence to be presented simultaneously, more clearly shows the detailed flow evolution. For the non-reacting jet we see the passage and growth of large-scale organized structures up through the jet column, the axial velocity decay of the structures, the fluid entrainment patterns, and occasional pairing events. A rendering of a non-sequential set of images shows no discernible organized component. Volume rendering of the reacting jet shows a similar pattern of burning large-scale organized structures which convect over considerable axial distances but without the corresponding velocity decay, similar to observations of laboratory flames. The images presented here are believed to be some of the most direct visual evidence to date for large-scale organized motions in the far-field of high Reynolds number, fully developed jets and jet flames. Since conditional sampling techniques are not used, we believe that the volume renderings seen here are likely to be representative of the natural development of jet flows.

show abstract

Section: Introductionmentioning

confidence: 99%

Large-scale dynamics in high Reynolds number jets and jet flames

Mungal

Lozano

Cruyningen

1992

Experiments in Fluids

View full text Add to dashboard Cite

show abstract

“…[15] In spite of the large amount of work on this topic, there is no consensus on a single measure of mixing that can be used for different processes nor is there a single mixing index that can be implemented easily for different scenarios varying from numerical simulations to laboratory experiments to industrial processes. [16][17][18][19] In this paper we present an approach for measuring the degree of mixing of several fluids that is independent of the physical process responsible for mixing and that relies on the information entropy. This approach is particularly suited for polymerprocessing operations where process control and enhanced Summary: We introduce a methodology to quantify the quality of mixing in various systems, including polymeric ones, by adapting the Shannon information entropy.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Fluid Mixing with the Shannon Entropy

Camesasca

Kaufman

Manas‐Zloczower

2006

Macro Theory & Simulations

View full text Add to dashboard Cite

Summary: We introduce a methodology to quantify the quality of mixing in various systems, including polymeric ones, by adapting the Shannon information entropy. For illustrative purposes we use particle advection of two species in a two‐dimensional cavity flow. We compute the entropy by using the probability of finding a suitable chosen group/complex of particles of a given species, at a given location. By choosing the size of the group to be in direct proportion to the overall concentration of the components in the mixture we ensure that the entropic measure is maximized for the case of perfect mixing, that is, when at each location the component concentration is equal to the corresponding overall component concentrations. The scale of observation role in evaluating mixing is analyzed using the entropic methodology. We also illustrate the effect of initial conditions on mixing in a laminar system, typical in operations involving polymers. magnified image

show abstract

“…Laser-induced fluorescence (LIF) is frequently used in fluids research, such as the in flow visualization of turbulent mixing [117][118][119] and combustion processes [120][121][122], in (micro) particle image velocimetry (µPIV) [123,74], and in molecular tagging [124][125][126][127]. Molecular fluorescence imaging uses pulsed dye laser tuned for resonant spectroscopic excitation, while for the measurement of velocity fields pulsed Nd:YAG lasers provide the nonspecific fluorescence excitation of micron-sized or nanometer-sized tracer particles.…”

Section: High-speed Fluorescence Imagingmentioning

confidence: 99%

High-speed imaging in fluids

Versluis

2013

Exp Fluids

153

View full text Add to dashboard Cite

High-speed imaging is in popular demand for a broad range of experiments in fluids. It allows for a detailed visualization of the event under study by acquiring a series of image frames captured at high temporal and spatial resolution. This review covers high-speed imaging basics, by defining criteria for high-speed imaging experiments in fluids and to give rule-of-thumbs for a series of cases. It also considers stroboscopic imaging, triggering and illumination, and scaling issues. It provides guidelines for testing and calibration. Ultra high-speed imaging at frame rates exceeding 1 million frames per second is reviewed, and the combination of conventional experiments in fluids techniques with high-speed imaging techniques are discussed. The review is concluded with a high-speed imaging chart, which summarizes criteria for temporal scale and spatial scale and which facilitates the selection of a high-speed imaging system for the application.

show abstract

Measurements of entrainment and mixing in turbulent jets

Cited by 218 publications

References 24 publications

Large-scale dynamics in high Reynolds number jets and jet flames

Large-scale dynamics in high Reynolds number jets and jet flames

Quantifying Fluid Mixing with the Shannon Entropy

High-speed imaging in fluids

Contact Info

Product

Resources

About