Dispersion measurements in turbulent flows (boundary layer and plane jet)

Paranthoën, Pierre; Fouari, A.; Dupont, A.; Lecordier, Jean-Claude

doi:10.1016/0017-9310(88)90232-3

Cited by 24 publications

(11 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dispersion downstream sources in open flows is very sensitive to the size of the source relative to the turbulent length scale at the source location [37,38]. Unlike the previous situation, dispersion from sources located close to an obstacle, as in this experiment, is less sensitive to this effect due to the initial recirculation flow region zone.…”

Section: Methodscontrasting

confidence: 53%

Mixing in the three-dimensional wake of an experimental modelled vehicle

2011

View full text Add to dashboard Cite

Experimental results on tracer gas diffusion within the near wake of a simplified model car (Ahmed model with a rear slant angle of 25 • ) are presented. Pollutant emission is simulated using heated air injected through a small pipe at one side of the model base. Fine cold wire thermometry is used to measure instantaneous temperature excess and variance of temperature gradient in the near wake. Measurements of the three mean velocity components were made using a laser Doppler anemometers system. Characteristics of the mean and fluctuating temperature fields, time-averaged flow streamlines and scalar dissipation measurements are presented and discussed. The local mixing time scale is determined from the measured mean dissipation rate of temperature variance. Its value shows that micromixing is not a limiting phenomenon for chemical reactions in the near wake.

show abstract

Section: Methodscontrasting

confidence: 53%

Mixing in the three-dimensional wake of an experimental modelled vehicle

2011

View full text Add to dashboard Cite

show abstract

“…Following Paranthoën et al (1988), who successfully collapsed the peak mean temperature data from a variety of dispersion experiments (in boundary layers, plane jets and pipe flows) using the integral Lagrangian time scale of the transverse velocity fluctuation at the source location, we plot in figure 9 the downstream evolution of both the peak (centreline) value and the half-width of the mean temperature excess profiles using a quasi-Lagrangian non-dimensionalization of the downstream coordinate. Instead of non-dimensionalizing the downstream position (x) by the channel half-width (h) -as done in figure 7(a) -the flight time from the source (x/ U ) is non-dimensionalized by (an approximation of) the local Lagrangian time scale.…”

Section: Resultsmentioning

confidence: 99%

“…They presented statistics of the (mean and fluctuating) concentration field, along with measurements of various turbulent fluxes. Paranthoën et al (1988) studied the dispersion from a line source in both a turbulent boundary layer and a plane jet. Their results included the mean and fluctuating temperature fields, in addition to a rescaling scheme, which makes use of the Lagrangian integral time scale of the transverse velocity fluctuation (see also Dupont, El Kabiri & Paranthoën 1985), that provided a reasonable collapse of the (mean) statistics from both flows.…”

Section: Introductionmentioning

confidence: 99%

Lateral dispersion from a concentrated line source in turbulent channel flow

Lepore

Mydlarski

2011

J. Fluid Mech.

View full text Add to dashboard Cite

The dispersion of a passive scalar (temperature) from a concentrated line source in fully developed, high-aspect-ratio turbulent channel flow is studied herein. The line source is oriented in the direction of the inhomogeneity of the velocity field, resulting in a thermal plume that is statistically three-dimensional. This configuration is selected to investigate the lateral dispersion of a passive scalar in an inhomogeneous turbulent flow (i.e. dispersion in planes parallel to the channel walls). Measurements are recorded at six wall-normal distances (y/ h = 0.10, 0.17, 0.33, 0.50, 0.67 and 1.0), six downstream positions (x/ h = 4.0, 7.4, 10.8, 15.2, 18.6 and 22.0) and a Reynolds number of Re ≡ U y = h h/ν = 10 200 (Re τ ≡ u * h/ν = 502). The lateral mean temperature excess profiles were found to be well represented by Gaussian distributions. The rootmean-square (r.m.s.) profiles, on the other hand, were symmetric, but non-Gaussian. Consistent with homogeneous flows (and in contrast to the work of Lavertu & Mydlarski (J. Fluid Mech., vol. 528, 2005, p. 135) studying transverse dispersion in the same flow), (i) the downstream growth rate of the centreline mean temperature excess, centreline r.m.s. temperature fluctuation and half-width of the mean and r.m.s. temperature profiles followed a power law evolution in the downstream direction, and (ii) the r.m.s. profiles evolved from single-peaked to double-peaked profiles far downstream. By comparing the measured ratios of the centreline r.m.s. temperature fluctuation to the mean temperature excess to the ratios measured in other flows, it was hypothesized that the mean-flow shear, as well as the turbulence intensity, played an important, cooperative role in increasing the mixedness of the flow. The probability density functions (PDFs) were quasi-Gaussian near the wall as well as for largeenough downstream distances. Closer to both the source and the channel centreline, the PDFs were better approximated by exponential distributions, with a sharp peak corresponding to the free-stream temperature. For intermediate downstream distances, the PDFs of the lateral dispersion were better mixed than analogous PDFs of the transverse dispersion, consistent with the mixedness measurements.

show abstract

“…However for these authors the precise value of the effective temperature being used was not clear. It is worth to note that in studies devoted to the diffusion of heat downstream a line source located in a turbulent flow the authors rather use, up to now, the wire temperature (Uberoi and Corrsin (1953), Crum and Hanratty (1965)) or the film temperature (the temperature halfway between the cylinder temperature and the free stream temperature) (Shlien and Corrsin (1976), Paranthoen et al (1988)) to identify an effective kinematic viscosity.…”

Section: Introductionmentioning

confidence: 99%

The control of vortex shedding behind heated circular cylinders at low Reynolds numbers

Lecordier

Hamma

Paranthoën

1991

Experiments in Fluids

Self Cite

102

View full text Add to dashboard Cite

We report some experiments undertaken to investigate the control of vortex shedding behind electrically heated cylinders at low Reynolds numbers owing to the heat input brought to the cylinder. In airflow, depending on the Reynolds number value, complete suppression or modification of the vortex shedding phenomenon can be achieved with increase of heat input. Experimental results suggest that this control could result of a slight change of the separation point location due to the increase of the dynamic viscosity of the fluid.

show abstract

Dispersion measurements in turbulent flows (boundary layer and plane jet)

Cited by 24 publications

References 21 publications

Mixing in the three-dimensional wake of an experimental modelled vehicle

Mixing in the three-dimensional wake of an experimental modelled vehicle

Lateral dispersion from a concentrated line source in turbulent channel flow

The control of vortex shedding behind heated circular cylinders at low Reynolds numbers

Contact Info

Product

Resources

About