Scalar Mixing Layer in Grid Turbulence with Transport of Passive and Reactive Species

1989 ◽  
pp. 109-118 ◽  
Author(s):  
L. R. Saetran ◽  
D. R. Honnery ◽  
S. H. Stårner ◽  
R. W. Bilger
Keyword(s):  
Mixing Layer ◽  
Reactive Species ◽  
Grid Turbulence ◽  
Scalar Mixing

Lagrangian micromixing modelling of reactive scalar statistics: scalar mixing layer in decaying grid turbulence

2015 ◽  
Vol 58 (4) ◽  
pp. 251 ◽  
Author(s):  
Andrea Amicarelli ◽  
Giovanni Leuzzi ◽  
Paolo Monti ◽  
Nicola Pepe ◽  
Guido Pirovano
Keyword(s):  
Mixing Layer ◽  
Grid Turbulence ◽  
Scalar Mixing ◽  
Reactive Scalar

0140 Basic Characteristics of the High-Schmidt Number Scalar Mixing Layer by Multiscale Grid Turbulence

2010 ◽  
Vol 2010 (0) ◽  
pp. 85-86
Author(s):  
Ryota UKAI ◽  
Hiroki SUZUKI ◽  
Kouji NAGATA ◽  
Yasuhiko SAKAI ◽  
Osamu TERASHIMA
Keyword(s):  
Schmidt Number ◽  
Mixing Layer ◽  
Grid Turbulence ◽  
Scalar Mixing ◽  
High Schmidt Number ◽  
Basic Characteristics

Implicit large eddy simulation of a scalar mixing layer in fractal grid turbulence

2016 ◽  
Vol 91 (7) ◽  
pp. 074007 ◽  
Author(s):  
Tomoaki Watanabe ◽  
Yasuhiko Sakai ◽  
Kouji Nagata ◽  
Yasumasa Ito ◽  
Toshiyuki Hayase
Keyword(s):  
Large Eddy Simulation ◽  
Mixing Layer ◽  
Grid Turbulence ◽  
Scalar Mixing ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Implicit Large Eddy Simulation

Reaction in a scalar mixing layer

1991 ◽  
Vol 233 ◽  
pp. 211-242 ◽  
Author(s):  
R. W. Bilger ◽  
L. R. Saetran ◽  
L. V. Krishnamoorthy
Keyword(s):  
Chemical Reaction ◽  
Mixing Layer ◽  
Reacting Flow ◽  
Scalar Mixing ◽  
Scalar Theory ◽  
Thermal Mixing ◽  
Fast Chemistry ◽  
The Mean ◽  
Reactive Scalars ◽  
Made In

Reaction in a scalar mixing layer in grid-generated turbulence is studied experimentally by doping half of the flow with nitric oxide and the other half with ozone. The flow conditions and concentrations are such that the chemical reaction is passive and the flow and chemical timescales are of the same order. Conserved scalar theory for such flows is outlined and further developed; it is used as a basis for presentation of the experimental results. Continuous measurements of concentration are limited in their spatial and temporal resolution but capture sufficient of their spectra for adequate second-order correlations to be made. Two components of velocity have been measured simultaneously with hot-wire anemometry. Conserved scalar mixing results, deduced from reacting and non-reacting measurements of concentration, show the independence of concentration level and concentration ratio expected for passive reacting flow. The results are subject to several limitations due to the necessary experimental compromises, but they agree generally with measurements made in thermal mixing layers. Reactive scalar statistics are consistent with the realizability constraints obtainable from conserved scalar theory where such constraints apply, and otherwise are generally found to lie between the conserved scalar theory limits for frozen and very fast chemistry. It is suggested that Toor's (1969) closure for the mean chemical reaction rate could be improved by interpolating between the frozen and equilibrium values for the covariance. The turbulent fluxes of the reactive scalars are found to approximately obey the gradient model but the value of the diffusivity is found to depend on the Damköhler number.

The effects of unstable stratification and mean shear on the chemical reaction in grid turbulence

2000 ◽  
Vol 408 ◽  
pp. 39-52 ◽  
Author(s):  
KOUJI NAGATA ◽  
SATORU KOMORI
Keyword(s):  
Chemical Reaction ◽  
Turbulent Mixing ◽  
Mixing Layer ◽  
Stratified Flow ◽  
Laser Doppler Velocimeter ◽  
Grid Turbulence ◽  
Unstable Stratification ◽  
Sheared Flow ◽  
Small Scales ◽  
Neutrally Stratified

The effects of unstable thermal stratification and mean shear on chemical reaction and turbulent mixing were experimentally investigated in reacting and non-reacting liquid mixing-layer flows downstream of a turbulence-generating grid. Experiments were carried out under three conditions: unsheared neutrally stratified, unsheared unstably stratified and sheared neutrally stratified. Instantaneous velocity and concentration were simultaneously measured using the combination of a laser-Doppler velocimeter and a laser-induced fluorescence technique. The results show that the turbulent mixing is enhanced at both large and small scales by buoyancy under unstably stratified conditions and therefore the chemical reaction is strongly promoted. The mean shear acts to enhance the turbulent mixing mainly at large scales. However, the chemical reaction rate in the sheared flow is not as large as in the unstably stratified case with the same turbulence level, since the mixing at small scales in the sheared neutrally stratified flow is weaker than that in the unsheared unstably stratified flow. The unstable stratification is regarded as a better tool to attain unsheared mixing since the shearing stress acting on the fluid is much weaker in the unstably stratified flow than in the sheared flow.

A Turbulent Model for Gas-Particle Jets

2000 ◽  
Vol 122 (3) ◽  
pp. 505-509 ◽  
Author(s):  
J. Garcı´a ◽  
A. Crespo
Keyword(s):  
Mixing Layer ◽  
Stokes Number ◽  
Particle Dispersion ◽  
Lagrangian Model ◽  
Grid Turbulence ◽  
Mean Velocity ◽  
Dissipation Term ◽  
Particle Flows ◽  
Integral Scales ◽  
Kolmogorov Constant

This work is concerned with turbulent diffusion in gas-particle flows. The cases studied correspond to dilute flows and small Stokes number, this implies that the mean velocity of the particles is very similar to that of the fluid element. The classical k-ε method is used to model the gas-phase, modified with additional terms for the k and ε equations, that takes into account the effect of particles on the carrier phase. The additional dissipation term included in the equation for k is due to the slip between phases at an intermediate scale, far from both the Kolmogorov and the integral scales. This term has a proportionality constant equal to 3/2 of Kolmogorov constant, C0. In this paper, a value of 3.0 has been used for this constant as suggested by Du et al., 1995, “Estimation of the Kolmogorov Constant C0 for the Langarian Structure Using a Second-Order Lagrangian Model of Grid Turbulence,” Phys. Fluids 7, (12), pp. 3083–3090. The additional source term for the ε equation is taken as proportional to ε/k, as is usually done. In all experiments analyzed the particles increased the dissipation of turbulent kinetic energy. A comparison is made between the results obtained with the model proposed in this work and the experiments of Shuen et al., 1985, “Structure of Particle-Laden Jets: Measurements and Predictions,” AIAA Journal, 23, No. 3, and Hishida et al., 1992, “Experiments on Particle Dispersion in a Turbulent Mixing Layer,” ASME Journal of Fluids Engineering, 119, pp. 181–194. [S0098-2202(00)02103-9]

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