Power spectrum of high Schmidt number scalar in a turbulent jet at a moderate Reynolds number

2021 ◽  
Vol 62 (6) ◽  
Author(s):  
Koji Iwano ◽  
Jumpei Hosoi ◽  
Yasuhiko Sakai ◽  
Yasumasa Ito
Keyword(s):  
Reynolds Number ◽  
Power Spectrum ◽  
Schmidt Number ◽  
Turbulent Jet ◽  
High Schmidt Number ◽  
Moderate Reynolds Number

scholarly journals Differential diffusion of high-Schmidt-number passive scalars in a turbulent jet

2008 ◽  
Vol 612 ◽  
pp. 439-475 ◽  
Author(s):  
T. M. LAVERTU ◽  
L. MYDLARSKI ◽  
S. J. GASKIN
Keyword(s):  
Reynolds Number ◽  
Schmidt Number ◽  
Reynolds Numbers ◽  
Turbulent Jet ◽  
Passive Scalars ◽  
Concentration Difference ◽  
Differential Diffusion ◽  
High Schmidt Number ◽  
Diffusion Effects ◽  
High Reynolds

The separate evolution, or differential diffusion, of high-Schmidt-number passive scalars in a turbulent jet is studied experimentally. The two scalars under consideration are disodium fluorescein (Sc≡ ν/D= 2000) and sulforhodamine 101 (Sc= 5000). The objectives of the research are twofold: to determine (i) the Reynolds-number-dependence, and (ii) the radial distribution of differential diffusion effects in the self-similar region of the jet. Punctual laser-induced fluorescence (LIF) measurements were obtained 50 jet diameters downstream of the nozzle exit for five Reynolds numbers (Re≡uod/ν = 900, 2100, 4300, 6700 and 10600, whereu0is the jet exit velocity,dis the jet diameter, and ν is the kinematic viscosity) and for radial positions extending from the centreline to the edges of the jet cross-section (0 ≤r/d≤ 7.5). Statistics of the normalized concentration difference,Z, were used to quantify the differential diffusion. The latter were found to decay slowly with increasing Reynolds number, with the root mean square ofZscaling asZrms≡ 〈Z2〉1/2∝Re−0.1, (or alternatively 〈Z2〉 ∝Re−0.2). Regardless of Reynolds number, differential diffusion effects were found to increase away from the centreline. The increase in differential diffusion effects with radial position, along with their increase with decreasing Reynolds number, support the hypothesis of increased differential diffusion at interfaces between the jet and ambient fluids. Power spectral densities ofZwere also studied. These spectra decreased with increasing wavenumber – an observation attributed to the decay of the scalar fluctuations in a turbulent jet. Furthermore, these spectra showed that significant differential diffusion effects persist at scales larger than the Kolmogorov scale, even for moderately high Reynolds numbers.

Models of the scalar spectrum for turbulent advection

1978 ◽  
Vol 88 (3) ◽  
pp. 541-562 ◽  
Author(s):  
R. J. Hill
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Schmidt Number ◽  
Temperature Fluctuations ◽  
Limited Extent ◽  
Temperature Spectrum ◽  
One Dimensional ◽  
Moderate Reynolds Number ◽  
Temperature Spectra ◽  
High Reynolds

Several models are developed for the high-wavenumber portion of the spectral transfer function of scalar quantities advected by high-Reynolds-number, locally isotropic turbulent flow. These models are applicable for arbitrary Prandtl or Schmidt number, v/D, and the resultant scalar spectra are compared with several experiments having different v/D. The ‘bump’ in the temperature spectrum of air observed over land is shown to be due to a tendency toward a viscous-convective range and the presence of this bump is consistent with experiments for large v/D. The wavenumbers defining the transition between the inertial-convective range and viscous-convective range for asymptotically large v/D (denoted k* and k1* for the three- and one-dimensional spectra) are determined by comparison of the models with experiments. A measurement of the transitional wavenumber k1* [denoted (k1*)s] is found to depend on v/D and on any filter cut-off. On the basis of the k* values it is shown that measurements of β1 from temperature spectra in moderate Reynolds number turbulence in air (v/D = 0·72) maybe over-estimates and that the inertial-diffusive range of temperature fluctuations in mercury (v/D ≃ 0·02) is of very limited extent.

149 Study on turbulent jet diffusion with a chemical reaction at a high Schmidt number

2015 ◽  
Vol 2015.64 (0) ◽  
pp. _149-1_-_149-2_
Author(s):  
Takahiro NAITO ◽  
Tomoaki WATANABE ◽  
Yasuhiko SAKAI ◽  
Kouji NAGATA ◽  
Yasumasa ITO ◽  
...  
Keyword(s):  
Chemical Reaction ◽  
Schmidt Number ◽  
Turbulent Jet ◽  
High Schmidt Number

scholarly journals Measurements of scalar power spectra in high Schmidt number turbulent jets

1996 ◽  
Vol 308 ◽  
pp. 129-146 ◽  
Author(s):  
Paul L. Miller ◽  
Paul E. Dimotakis
Keyword(s):  
Reynolds Number ◽  
Schmidt Number ◽  
Logarithmic Derivative ◽  
Power Spectra ◽  
Turbulent Jets ◽  
Reynolds Numbers ◽  
Normal Function ◽  
Absolute Value ◽  
High Schmidt Number ◽  
Log Normal

We report on an experimental investigation of temporal, scalar power spectra of round, high Schmidt number (Sc ≃ 1.9 × 103), momentum-dominated turbulent jets, for jet Reynolds numbers in the range of 1.25 × 104 ≤ Re ≤ 7.2 × 104. At intermediate scales, we find a spectrum with a slope (logarithmic derivative) that increases in absolute value with Reynolds number, but remains less than 5/3 at the highest Reynolds number in our experiments. At the smallest scales, our spectra exhibit no k−1 power-law behaviour, but, rather, seem to be approximated by a log-normal function, over a range of scales exceeding a factor of 40, in some cases.

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