Shock Waves (1999) 9: 215 218
Report on the 6th International Workshop on the Physics
of Compressible Turbulent Mixing
L. Houas1, G. Jourdan1, E. Meshkov2, D. Besnard3, J.-F. Haas4
1
IUSTI-CNRS 6595, Universit� de Provence, Technop�le de Ch�teau Gombert, 5 rue Enrico Fermi, 13453 Marseille cedex 13,
France
2
Institute of Experimental Physics, VNIIEF-Sarov, 607190, Nizhni Novgorod Region, Russia
3
CEA-DRN, DTP-17 rue des Martyrs, 38054 Grenoble cedex 9, France
4
Commissariat ą l Energie Atomique/DRIF/DCRE/SCSE, B.P. 12, 91680 BruyŁres-le-Chatel, France
Received 8 September 1997 / Accepted 8 September 1997
Key words: Rayleigh Taylor and Richtmyer Meshkov instabilities, Compressible turbulent mixing,
Shock-interface interaction
The sixth International Workshop on the Physics of Com- who are not mentioned because we have not recieved their
pressible Turbulent Mixing (IWPCTM) was held in Mar- papers at the time of this preliminary review.
seille (France) June 18 21, 1997, in the IUSTI building of We separate this analysis into experiments, simula-
the University of Provence. The first IWPCTM was held in tions and theory even though many papers included two
Princeton (NJ, USA) in 1988, soon followed by the second approaches. About 36% of the workshop contributions
in Pleasanton (CA, USA) in 1989. From this time these were in the experimental domain. Many of the experimen-
conferences have been repeated every two years: Royau- tal works presented were fulfilled at large installations,
mont (France, 1991), Cambridge (UK, 1993) and Stony such as laser facilities: PHEBUS (France), NOVA (USA),
Brook (NY, USA, 1995). The main topics of these work- HELEN (UK), ISKRA-4 (Russia), GEKKO-XII (Japan)
shops deal with problems of hydrodynamic instabilities and PEGASUS Z-Pinch Machine (USA). The laser exper-
of different density fluid interfaces subjected to constant iments have become more precise. Coupled with numeri-
or varying acceleration (Rayleigh Taylor (RT) instabil- cal simulations, they provide unique data on the RM and
ity) and (steady) shock wave impulsive-type acceleration RT instabilities at high energy density. A series of experi-
(Richtmyer Meshkov (RM) instability), at all the stages, ments has been conducted on the NOVA laser facility, and
i.e. from the development of the initial small perturbation use of the NOVA hohlraum as the driver source to launch
to the turbulent mixing. a high-Mach-number (M = 30) shock wave into a minia-
The total number of participants who registered was ture shock tube attached to the hohlraum. This set-up was
113 from 9 countries: Russia (35), USA (30), France (29), used to investigate the RM instability: the development of
Israel (8), UK (5), Switzerland (2), Japan (1), Spain (2) the initial perturbation with broad-range amplitude and
and China (1). During the workshop, 47 oral presentations wavelength variations at the interface between brominated
were given (in plenary sessions), and 58 posters were pre- plastic and low-density carbon foam (L. Logory et al.); the
sented and discussed. As shown in Fig. 1, two particular development of broad-spectrum, multimode initial pertur-
types of work were presented: first, about half of the pre- bation up to the turbulent mixing zone (D. Farley et al.).
sentations consist of numerical studies, and, second, after In the last case, the present experimental results give a
ten years of research in this topics, we observe for the coefficient of 0.87 in the power-law dependence of turbu-
first time the appearance of general papers on the subject lent mixing zone growth with time. This value is higher
(Il kaev et al., Rozanov and Peyser et al.). The 6th IW- than the one from previously published results. Some ad-
PCTM contained papers presented by groups (often inter- ditional information about these experiments is given by
national) of many scientists. This results from the collab- T. Peyser et al. A similar method (NOVA hohlraum as a
orative structure of ISTC projects within Russia as well as driver) was used (K. Budil et al.) to investigate the mul-
from contracts between Western and Russian institutions timode RT instability. The experiments attempted to ob-
and collaboration between Western laboratories. There- serve the process of bubble competition in the turbulent
fore in our analysis, we will often cite the first author only mixing zone. Of special interest are NOVA investigations
of each publication. Furthermore, we apologize for authors into the effect of spherical convergence on RT instabil-
ity growth and saturation, as shown by S. Glendinning
Correspondence to: L. Houas et al. An embedded-interface RM-RT experiment to look
216 L. Houas et al.: Report on the 6th International Workshop on the Physics of Compressible Turbulent Mixing
at deep non-linear mixing relevant to supernovae was also Some results of RT instability experiments have been
presented by Remington et al. Experiments on RT turbu- presented. They were conducted at the LEM facility, which
lent mixing of multi-thin-layered targets of materials with allows arbitrary temporal acceleration profiles g(t) (G. Di-
different densities have been conducted on the ISKRA-4 monte et al., M. Schneider et al.). The width and structure
facility (V. Andronov et al.). of the mixing zone of two fluids was observed in these ex-
Unfortunately, we have to inform our colleagues that periments. Another peculiarity of this work is the applica-
Vladimir Andronov, who had co-authored many papers in tion of yogurt as a low-strength material. Now a few words
this field, died a few months before the 6th IWPCTM. about new experimental methods. The method of laser
H. Takabe presented a review of hydrodynamic insta- interferometric tomography (LIT) presents new possibili-
bility experiments at the GEKKO-XII laser facility. The ties to investigate the structure of the gas/gas turbulent
first experiments realized with the PEGASUS Z-Pinch mixing zone. V. Bashurin et al. have measured the dis-
machine to image inertial instabilities of cylindrically con- tribution of the propane concentration in the 3D propane
vergent interfaces were also presented (E. Chandler et al.). jet in air, using the LIT technique. A new method to cre-
This work is one of the series of studies to investigate insta- ate 3D initial perturbation at the interface of two gases
bilities in solid materials. The effects of material strength in shock tube experiments was presented in the talk by
on the growth of RT unstable interfaces was also examined M. Bliznetsov et al. F. Poggi et al. presented a paper
on experiments in the NOVA laser (D. Kalantar et al.). about using laser doppler velocimetry (LDV) to measure
An X-ray drive was used in these experiments to shock vertical velocity component in the turbulent mixing zone
compress at about 3 Mbar and accelerate Cu foils. RT in- in (vertical) shock tube experiments. G. Jourdan et al.
stability in Ti plates accelerated by products of chemical have investigated possibilities to measure the turbulent
HE explosion was investigated (A. Lebedev et al.) in ex- mixing zone width in shock tube experiments by using
periments in which the stability area boundary at loading hot wire anemometry (HWA). A. Podulalov presented a
pressure Pmax = 37 GPa was defined. description of the software package Autoview v. 2.7 for
Traditional topics in all these workshops were shock Windows 95, which can be used for turbulent mixing zone
tube experiments, and it was the same for the 6th. A. Ale- image processing in shock tubes and similar facility experi-
shin et al. presented a set of experimental studies of RM ments (for both plane and cylindrical geometry). This soft-
instability in shock tubes under various initial conditions ware has been successfully applied in the VNIIEF-Sarov
(amplitude and wavelength, Atwood number, shock wave Institute of Experimental Physics (Russia).
Mach number, 2D and 3D initial perturbation). Interac- The different works presented within the framework of
tion of the stationary shock waves with a turbulent mixing the 6th International Workshop on the Physics of Com-
zone from a gas/gas interface has been investigated and pressible Turbulent Mixing are mainly numerical stud-
published by both Y. Kucherenko et al. and E. Lazareva ies (46% of the presentations): more and more 3D cal-
et al. Investigation on turbulent mixing zone development culations are performed, improved turbulence models are
at an air/H2 interface driven by a convergent cylindrical introduced into 2D codes while some research into ad-
shock wave was presented by E. Meshkov et al. S. Zaytsev vanced models imbedded in 1D codes continues. Q. Zhang
et al. have investigated the RT instability development and M.J. Graham presented a very interesting numeri-
of a gas/gas interface accelerated by a compression wave. cal work of the RM instability in a cylindrical geome-
Some interesting new results on RM instability and tur- try with the study of unstable finger growth driven by
bulent mixing are reported by D. Shvarts et al. and Sadot shock waves of various Mach numbers. R. Cohen et al.
et al. A. Smith et al. have presented results of the inves- showed 3D high-resolution simulations of the RM insta-
tigation into a single discrete 2D perturbation develop- bility using the piecewise-parabolic method (PPM), and
ment in shock tube experiments. A series of experiments O. Schilling et al. have used the same approach for the RT
(Y. Kucherenko et al.) was performed at both the EKAP instability. R. Baltrusaitis et al. proposed simulations of
(X-ray technique) and SOM (light technique) installations the RM instability in gas-curtain experiments using radia-
to investigate the behavior of a turbulized mixture of two tion adaptive grid eulerian (RAGE), a 2D Eulerian-based
liquids with different density, at the stage of inertial mo- hydrodynamics code, which features adaptive mesh refine-
tion, and also the separation rate of such mixtures when ment in order to follow vorticity generation and complex
the sign of the acceleration abruptly changes. Models pre- flow patterns. The RAGE code has also been used in solv-
pared from jelly (of water-solved gelatine) behave like liq- ing different flow problems for weak and stronger shock
uid even at moderate pressure (10 atm). A number of in- (R. Weaver et al.). J. Grove et al. have shown the possi-
teresting topics in this area were reported at the previous bility to use front-tracking computations for high-Mach-
workshop. The jelly method was used to investigate the number and large amplitude RM instability. Simulations
influence of the geometry (cylindrical and plane) of the of RT instability growth in a converging geometry for NIF
unstable surface of the jelly layer on the rate of the RT and NOVA implosions have also been presented (S. Haan
turbulent mixing zone development (M. Kamchibekov et et al.). The paper by X. Li and Q. Zhang shows the interest
al.) and in the spherical case (E. Meshkov et al.). The in the total variation diminishing/artificial compression
development of the perturbation at the RT unstable sur- method for the RM instability under computational mesh
faces of a cylindrical convergent shell was investigated by refinement. Spike and bubble structures are described in
S. Weir et al. the simulations of the RM instability NOVA experiments
L. Houas et al.: Report on the 6th International Workshop on the Physics of Compressible Turbulent Mixing 217
using a 2D arbitrary Lagrangian Eulerian hydrodynamics interface separated SF6 from air and the incident Mach
code CALE (L. Logory et al. and T. Peyser et al.). number was 1.44 in SF6. As the results from the four par-
Simulations of high-Mach-number escaped vortex pro- ticipating groups were in agreement, it is felt that future
jectiles in shock bubble interations for ellipsoidal and sphe- test cases should deal with more complex initial condi-
rical geometry, using 2D second-order Godunov and Har- tions leading to chaotic mixing. The other test case deals
ten Yee codes, are presented in the works by S. Zeng with the interaction of a weak and a strong shock wave
and N. Zabusky. A 2D and 3D parallel ALE hydrody- with an oblique gas layer. It was prepared by L. Chodorge
namics code for modeling turbulent flows induced by RT and F. Renaud. The work was done by two groups using
instability has been developed and exposed (T. McAbee). three codes but the comparison between the two groups
S. Belkov et al. presented their results concerning the evo- is hampered by the different format of the results.
lution of the RT instability under the influence of the RM About 16% of the presentations deal with theory and
stage with the 2D MIMOZA code. The 2D and 3D Eu- modeling. The nonlinear phase is now better understood
ler code NUT and a 2D Lagrangian-Euler code ATLANT for the RMI. It appears that large-scale interpenetration
were also presented by both I. Lebo et al. and Nikishin of materials should be treated by two-phase models, while
et al. for the simulation of shock tube and laser-driven turbulent modeling applies better to small scales. The ef-
experiments. Some descriptions of a numerical simulation fects of compressibility are well explored by modeling and
of turbulent mixing in 1D and 2D flows using a VIKHR- simulation. A spectral turbulent model explicitly incorpo-
model-implemented EGAK-V complex program, for dif- rating the nonlocal nature of the pressure effects in an
ferent initial configurations was given (V. Nikiforov et al., inhomogeneous environment was presented in comparison
V. Dudin et al. and Y. Yanilkin et al.). A similar tur- with some different RT instability experiments (T. Clark
bulent mixing model has been used in the 1D numerical et al.). The effect of compressibility on the interaction of
studies by E. Valerio et al. and Z. Zhang and J. Wang. shocks with stratified fluid layers has been examined for
Also, O. Sinkova et al. have proposed a 3D direct numer- both various Mach and Atwood numbers by D. Meiron and
ical simulation of gravitational turbulent mixing using a M. Meloon. 2D analytical results concerning the baroclinic
TREK code package. Several 1D, 2D and 3D numerical circulation generation on shock-accelerated slow/fast in-
investigations, using the package MAH and MECH, for terfaces have been presented and validated by quantifi-
solving RT, RM and KH instability problems were pre- cations of numerical simulations (R. Samtaney et al.).
sented (the group of N. Anuchina et al.). A nonlinear theory, based on the method of Pad� ap-
In view of a correct description of the transitional proximation, for the growth of the spikes and bubbles at
and turbulent flows, E. Fournier et al. developed a so- RM instable interfaces of arbitrary density ratio in two
phisticated domain decomposition method for 2D pseudo- and three dimensions has been proposed (Q. Zhang and
spectral parallel Navier Stokes simulations of RT insta- S. Sohn). A theoretical study of turbulent mixing result-
bility. L. Hallo et al. showed some numerical computa- ing from the combined influence of shear and gravitational
tions using both the linear perturbation code PANSY and (convective) instabilities, based on semi-empirical model
the 2D Lagrangian code FCI2 involving both incompress- using the equation of balance for kinetic energy of turbu-
ible and compressible flows. Interesting large-eddy simula- lence, was presented by V. Neuvazhayev and I. Parshukov.
tions (LES) of mixing layers using the filtered structure- Some progress in theoretical research on hydrodynamical
function model and pseudo-spectral in the three dimen- instabilities and turbulent mixing related to the problem
sions of space numerical methods were presented (M. Le- of laser target compression was reported (V. Rozanov,
sieur et al.). The purpose of the work by C. Mugler and N. Zmitrenko et al.). Further, one can note the original
S. Gauthier was to illustrate the contribution of numer- fractal approach for investigation of the geometrical struc-
ical simulations to interpret RM-instability-induced mix- ture of reactive fronts and shock tube mixing layers shown
ing flows in shock tube experiments and the influence of by J. Redondo. Different nonlinear models of multi-mode
the wall boundary layer, using a CFDLIB inviscid code interfacial perturbations in RT instability laser experi-
which solves the Navier Stokes equations with a second- ments were discussed (C. Cherfils-Cl�rouin and D. Gal-
order Godunov method. G. Lacassin et al. presented 2D miche). A unified presentation of models for predicting lin-
numerical simulations carried out with the HESIONE com- ear perturbation growth in both cylindrical and spherical
puter program for a large-scale RM instability. S. Dalziel geometries was reported (L. Hallo et al.). A new general
et al. detailed some numerical simulations of RT insta- formula for the growth rate of RM instability in its linear
bility obtained from both a simple 2D stream-function- phase was been presented by Vandenboomgaerde et al. in
vorticity code CFX (Flow3D) and a 3D high-resolution the framework of the impulsive model for both heavy/light
TURMOIL3D, which was further described by D. Youngs and light/heavy configurations. An analysis of a recently
with the case of a variable-acceleration-induced RT mix- proposed two-phase model for the statistical evolution of
ing. physical quantities inside the mixing zone induced by RT
Two numerical test cases have been suggested for code instability was reported (J. Glimm et al.). Analytic for-
comparison. One case is about the simulation of a 3D mulas, based on an extension of Layzers theory, for non-
bulged interface in a square shock tube leading to a large linear evolution of the bubble amplitude in RT and RM
scale Richtmyer Meshkov instability after an incident and instabilities in two and three dimensions, were presented
two reflected shock waves (Lacassin et al.). The bulged by K. Mikaelian. A theoretical model for the ablatively
218 L. Houas et al.: Report on the 6th International Workshop on the Physics of Compressible Turbulent Mixing
The meeting was concluded with summary discussions
on progress in experiments, numerical simulation and the-
ory for the RT and RM mixing problem. Our analysis
above takes into account some of these discussions.
The proceedings of this workshop is now available.
Please contact Dr. Georges Jourdan:
fax [phone],
e-mail [e-mail].
The scientific committee meeting was held on Thursday
June 19th, 1997. The place and chairman of the next work-
shop were determined by vote. The Seventh International
Workshop on the Physics of Compressible Turbulent Mix-
ing will be held in Russia and will be chaired by Dr. E.
Meshkov of the Institute of Experimental Physics of the
Sarov Russian Federal Nuclear Centre.
Fig. 1. Distribution of the 6th IWPCTM presentations in
experimental (Exp), numerical (Num), theoretical modeling
(Theo-Mod) and general (Gen) areas
Acknowledgements. L. Houas and G. Jourdan would like to ex-
press their sincere gratitude to the organizing committee mem-
bers and the 6th IWPCTM participants and companions, who
driven RT instability single-mode and multi-mode mixing
came from abroad and inside of France, and who made this
fronts was reported by D. Oron et al. A possible appli-
workshop scientifically and socially successful. Thanks to all of
cation of a new vortex model for RM instability at low
them.
Mach numbers has been discussed (A. Rekanati et al.) as
The 6th IWPCTM Organising Committee gratefully ac-
well as a new Layzer-type potential flow model, describ-
knowledges the following financial support organisations: Le
ing the bubble evolution in cylindrical geometry under RT
Conseil G�n�ral des Bouches-du-Rh�ne, le Commissariat ą l En-
and RM instability conditions (Y. Ydov et al.). The inter-
ergie Atomique-Direction des Applications Militaires, le Cen-
face evolution before and after a reflected shock in shock
tre National de la Recherche Scientifique, le MinistŁre des Af-
tube experiments has been studied from the investigation
faires EtrangŁres, l Universit� de Provence, the European Re-
of the nonlinear growth of a single-mode, two-bubble and search Community On Flow Turbulence And Combustion, and
random initial perturbation (D. Shvarts et al.). l Association Universitaire de M�canique.