The counterflow configuration is a canonical stagnation flow, featuring two opposed impinging round jets and a mixing layer across the stagnation plane. Although counterflows are used extensively in the study of reactive mixtures and other applications where mixing of two streams is required, quantitative data on the scaling properties of the flow field are lacking. The aim of this work is to characterize the velocity and mixing fields in isothermal counterflows over a wide range of conditions. The study features both experimental data from particle image velocimetry and results from detailed axisymmetric simulations. The scaling laws for the nondimensional velocity and mixture fraction are obtained as a function of an appropriate Reynolds number and the ratio of the separation distance of the nozzles to their diameter. In the range of flow configurations investigated, the nondimensional fields are found to depend primarily on the separation ratio and, to a lesser extent, the Reynolds number. The marked dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles, which becomes less important as the separation ratio decreases. The normalized strain rate and scalar dissipation rate at the stagnation plane are found to attain limiting values only for high values of the Reynolds number. These asymptotic values depend markedly on the separation ratio and differ significantly from the values produced by analytical models. The scaling of the mixing field does not show a limiting behavior as the separation ratio decreases to the smallest practical value considered.

1.
D. B.
Spalding
, “
Theory of mixing and chemical reaction in the opposed-jet diffusion flame
,”
ARS J.
31
,
763
771
(
1961
).
2.
H.
Schlichting
,
Boundary Layer Theory
, 8th ed. (
Springer
,
2000
).
3.
C. Y.
Wang
, “
Similarity stagnation point solutions of the Navier–Stokes equations–review and extension
,”
Eur. J. Mech.- B/Fluids
27
(
6
),
678
683
(
2008
).
4.
F. E.
Fendell
, “
Ignition and extinction in combustion of initially unmixed reactants
,”
J. Fluid Mech.
21
(
2
),
281
303
(
1965
).
5.
F.
Carbone
and
A.
Gomez
, “
Chemical interactions between 1, 2, 4-trimethylbenzene and n-decane in doped counterflow gaseous diffusion flames
,”
Proc. Combust. Inst.
35
(
1
),
761
769
(
2015
).
6.
F. A.
Williams
, “
A review of flame extinction
,”
Fire Saf. J.
3
(
3
),
163
175
(
1981
).
7.
B. G.
Sarnacki
,
G.
Esposito
,
R. H.
Krauss
, and
H. K.
Chelliah
, “
Extinction limits and associated uncertainties of nonpremixed counterflow flames of methane, ethylene, propylene and n-butane in air
,”
Combust. Flame
159
(
3
),
1026
1043
(
2012
).
8.
F. N.
Egolfopoulos
,
N.
Hansen
,
Y.
Ju
,
K.
Kohse-Höinghaus
,
C. K.
Law
, and
F.
Qi
, “
Advances and challenges in laminar flame experiments and implications for combustion chemistry
,”
Prog. Energy Combust. Sci.
43
,
36
67
(
2014
).
9.
A.
Alshaarawi
and
F.
Bisetti
, “
The effect of mixing rates on the formation and growth of condensation aerosols in a model stagnation flow
,”
J. Aerosol Sci.
81
,
34
46
(
2015
).
10.
J. C.
Rolon
,
D.
Veynante
,
J. P.
Martin
, and
F.
Durst
, “
Counter jet stagnation flows
,”
Exp. Fluids
11
(
5
),
313
324
(
1991
).
11.
H. K.
Chelliah
,
C. K.
Law
,
T.
Ueda
,
M. D.
Smooke
, and
F. A.
Williams
, “
An experimental and theoretical investigation of the dilution, pressure and flow-field effects on the extinction condition of methane-air-nitrogen diffusion flames
,”
Symp. (Int.) Combust.
23
,
503
511
(
1991
).
12.
C. E.
Frouzakis
,
J.
Lee
,
A. G.
Tomboulides
, and
K.
Boulouchos
, “
Two-dimensional direct numerical simulation of opposed-jet hydrogen-air diffusion flame
,”
Symp. (Int.) Combust.
27
,
571
577
(
1998
).
13.
V.
Mittal
,
H.
Pitsch
, and
F.
Egolfopoulos
, “
Assessment of counterflow to measure laminar burning velocities using direct numerical simulations
,”
Combust. Theory Modell.
16
(
3
),
419
433
(
2012
).
14.
N.
Bouvet
,
D.
Davidenko
,
C.
Chauveau
, and
L.
Pillier
, “
On the simulation of laminar strained flames in stagnation flows: 1D and 2D approaches versus experiments
,”
Combust. Flame
161
,
438
452
(
2014
).
15.
U.
Niemann
,
K.
Seshadri
, and
F. A.
Williams
, “
Accuracies of laminar counterflow flame experiments
,”
Combust. Flame
162
,
1540
1549
(
2015
).
16.
T. W.
Chapman
and
G. L.
Bauer
, “
Stagnation-point viscous flow of an incompressible fluid between porous plates with uniform blowing
,”
Appl. Sci. Res.
31
(
3
),
223
239
(
1975
).
17.
K.
Seshadri
and
F. A.
Williams
, “
Laminar flow between parallel plates with injection of a reactant at high reynolds number
,”
Int. J. Heat Mass Transfer
21
(
2
),
251
253
(
1978
).
18.
R. J.
Kee
,
J. A.
Miller
,
G. H.
Evans
, and
G.
Dixon-Lewis
, “
A computational model of the structure and extinction of strained, opposed flow, premixed methane-air flames
,”
Symp. (Int.) Combust.
22
,
1479
1494
(
1989
).
19.
A.
Liñán
,
D.
Martínez-Ruiz
,
A. L.
Sánchez
, and
J.
Urzay
, “
Regimes of spray vaporization and combustion in counterflow configurations
,”
Combust. Sci. Technol.
187
(
1-2
),
103
131
(
2015
).
20.
J. E.
Rehm
and
N. T.
Clemens
, “
The large-scale turbulent structure of nonpremixed planar jet flames
,”
Combust. Flame
116
,
615
626
(
1999
).
21.
R. J.
Adrian
, “
Particle-imaging techniques for experimental fluid mechanics
,”
Annu. Rev. Fluid Mech.
23
(
1
),
261
304
(
1991
).
22.
R. J.
Adrian
, “
Multi-point optical measurements of simultaneous vectors in unsteady flow–A review
,”
Int. J. Heat Fluid Flow
7
,
127
145
(
1986
).
23.
R. J.
Adrian
, “
Dynamic ranges of velocity and spatial resolution of particle image velocimetry
,”
Meas. Sci. Technol.
8
(
12
),
1393
(
1997
).
24.
A.
Leclerc
, “
Déviation d’un jet liquide par une plaque normale á son axe
,”
La Houille Blanche
6
,
816
821
(
1950
).
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