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Recent publications :
2023
Benseghier, Zeyd; Luu, Li-Hua; Cuellar, Pablo; Bonelli, Stephane; Philippe, Pierre
On the erosion of cohesive granular soils by a submerged jet: a numerical approach Journal Article
In: GRANULAR MATTER, vol. 25, no. 1, 2023, ISSN: 1434-5021.
@article{WOS:000896588700001,
title = {On the erosion of cohesive granular soils by a submerged jet: a
numerical approach},
author = {Zeyd Benseghier and Li-Hua Luu and Pablo Cuellar and Stephane Bonelli and Pierre Philippe},
doi = {10.1007/s10035-022-01289-5},
issn = {1434-5021},
year = {2023},
date = {2023-02-01},
journal = {GRANULAR MATTER},
volume = {25},
number = {1},
abstract = {This paper presents an erosion interpretation of cohesive granular
materials stressed by an impinging jet based on the results of a
micromechanical simulation model. The numerical techniques are briefly
described, relying on a two-dimensional Lattice Boltzmann Method coupled
with a Discrete Element Methods including a simple model of solid
intergranular cohesion. These are then used to perform a parametric
study of a planar jet in the laminar regime impinging the surface of
granular samples with different degrees of cohesive strength. The
results show the pertinence of using a generalized form of the Shields
criterion for the quantification of the erosion threshold, which is
valid for cohesionless samples, through empirical calibration, and also
for cohesive ones. Furthermore, the scouring kinetics are analysed here
from the perspective of a self-similar expansion of the eroded crater
leading to the identification of a characteristic erosion time and the
quantification of the classical erosion coefficient. However, the
presented results also challenge the postulate of a local erosion law
including erodibility parameters as intrinsic material properties. The
paper then reviews the main limitations of the simulation and current
interpretation models, and discusses the potential causes for the
observed discrepancies, questioning the pertinence of using
time-averaged macroscopic relations to correctly describe soil erosion.
The paper concludes addressing this question with a complementary study
of the presented simulations re-assessed at the particle-scale. The
resulting local critical shear stress of single grains reveals a very
wide dispersion of the data but nevertheless appears to confirm the
general macroscopic trend derived for the cohesionless samples, while
the introduction of cohesion implies a significant but systematic
quantitative deviation between the microscopic and macroscopic
estimates. Nevertheless, the micro data still shows consistently that
the critical shear stress does actually vary approximately in linear
proportion of the adhesive force.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
materials stressed by an impinging jet based on the results of a
micromechanical simulation model. The numerical techniques are briefly
described, relying on a two-dimensional Lattice Boltzmann Method coupled
with a Discrete Element Methods including a simple model of solid
intergranular cohesion. These are then used to perform a parametric
study of a planar jet in the laminar regime impinging the surface of
granular samples with different degrees of cohesive strength. The
results show the pertinence of using a generalized form of the Shields
criterion for the quantification of the erosion threshold, which is
valid for cohesionless samples, through empirical calibration, and also
for cohesive ones. Furthermore, the scouring kinetics are analysed here
from the perspective of a self-similar expansion of the eroded crater
leading to the identification of a characteristic erosion time and the
quantification of the classical erosion coefficient. However, the
presented results also challenge the postulate of a local erosion law
including erodibility parameters as intrinsic material properties. The
paper then reviews the main limitations of the simulation and current
interpretation models, and discusses the potential causes for the
observed discrepancies, questioning the pertinence of using
time-averaged macroscopic relations to correctly describe soil erosion.
The paper concludes addressing this question with a complementary study
of the presented simulations re-assessed at the particle-scale. The
resulting local critical shear stress of single grains reveals a very
wide dispersion of the data but nevertheless appears to confirm the
general macroscopic trend derived for the cohesionless samples, while
the introduction of cohesion implies a significant but systematic
quantitative deviation between the microscopic and macroscopic
estimates. Nevertheless, the micro data still shows consistently that
the critical shear stress does actually vary approximately in linear
proportion of the adhesive force.
Lemasquerier, D.; Favier, B.; Bars, M. Le
Zonal jets experiments in the gas giants' zonostrophic regime Journal Article
In: Icarus, vol. 390, pp. 115292, 2023.
@article{Lemasquerier_2023,
title = {Zonal jets experiments in the gas giants' zonostrophic regime},
author = {D. Lemasquerier and B. Favier and M. Le Bars},
url = {https://doi.org/10.1016%2Fj.icarus.2022.115292},
doi = {10.1016/j.icarus.2022.115292},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Icarus},
volume = {390},
pages = {115292},
publisher = {Elsevier BV},
abstract = {Intense east-west winds called zonal jets are observed in the atmospheres of Jupiter and Saturn and extend in their deep interior. We present experimental results from a fully three-dimensional laboratory analog of deep gas giants zonal jets. We use a rapidly rotating deep cylindrical tank, filled with water, and forced by a small-scale hydraulic circulation at the bottom. A topographic β-effect is naturally present because of the curvature of the free surface. Instantaneous turbulent zonal jets spontaneously emerge from the small-scale forcing, equilibrate at large scale, and can contain up to 70% of the total kinetic energy of the flow once in a quasi-steady state. We show that the spectral properties of the experimental flows are consistent with the theoretical predictions in the zonostrophic turbulence regime, argued to be relevant to gas giants. This constitutes the first fully-experimental validation of the zonostrophic theory in a completely three-dimensional framework. Complementary, quasi-geostrophic (QG) simulations show that this result is not sensitive to the forcing scale. Next, we quantify the potential vorticity (PV) mixing. While PV staircasing should emerge in the asymptotic regime of the gas giants, only a moderate PV mixing occurs because of the strong forcing and dissipation, as confirmed by QG simulations at smaller Ekman number. We quantify the local PV mixing by measuring the equivalent of a Thorpe scale, and confirm that it can be used to estimate the upscale energy transfer rate of the flow, which otherwise needs to be estimated from a much more demanding spectral analysis. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Chachanidze, Revaz; Xie, Kaili; Lyu, Jinming; Jaeger, Marc; Leonetti, Marc
Breakups of Chitosan microcapsules in extensional flow Journal Article
In: JOURNAL OF COLLOID AND INTERFACE SCIENCE, vol. 629, no. A, pp. 445-454, 2023, ISSN: 0021-9797.
@article{WOS:000860284900009,
title = {Breakups of Chitosan microcapsules in extensional flow},
author = {Revaz Chachanidze and Kaili Xie and Jinming Lyu and Marc Jaeger and Marc Leonetti},
doi = {10.1016/j.jcis.2022.08.169},
issn = {0021-9797},
year = {2023},
date = {2023-01-01},
journal = {JOURNAL OF COLLOID AND INTERFACE SCIENCE},
volume = {629},
number = {A},
pages = {445-454},
abstract = {The controlled rupture of a core-shell capsule and the timely release of
encapsulated materials are essential steps of the efficient design of
such carriers. The mechanical and physico-chemical properties of their
shells (or membranes) mainly govern the evolution of such systems under
stress and notably the link between the dynamics of rupture and the
mechanical properties. This issue is addressed considering weakly
cohesive shells made by the interfacial complexation of Chitosan and
PFacid in a planar extensional flow. Three regimes are observed, thanks
to the two observational planes. Whatever the time of reaction in
membrane assembly, there is no rupture in deformation as long as the
hydrodynamic stress is below a critical value. At low times of
complexation (weak shear elastic modulus), the rupture is reminiscent of
the breakup of dro-plets: a dumbell or a waist. Fluorescent labelling of
the membrane shows that this process is governed by continuous thinning
of the membrane up to the destabilization. It is likely that the
membrane shows a tran-sition from a solid to liquid state. At longer
times of complexation, the rupture has a feature of solid-like breakup
(breakage) with a discontinuity of the membrane. The maximal internal
constraint determined numerically marks the initial location of breakup
as shown. The pattern becomes more complex as the elon-gation rate
increases with several points of rupture. A phase diagram in the space
parameters of the shear elastic modulus and the hydrodynamic stress is
established.(c) 2022 Elsevier Inc. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
encapsulated materials are essential steps of the efficient design of
such carriers. The mechanical and physico-chemical properties of their
shells (or membranes) mainly govern the evolution of such systems under
stress and notably the link between the dynamics of rupture and the
mechanical properties. This issue is addressed considering weakly
cohesive shells made by the interfacial complexation of Chitosan and
PFacid in a planar extensional flow. Three regimes are observed, thanks
to the two observational planes. Whatever the time of reaction in
membrane assembly, there is no rupture in deformation as long as the
hydrodynamic stress is below a critical value. At low times of
complexation (weak shear elastic modulus), the rupture is reminiscent of
the breakup of dro-plets: a dumbell or a waist. Fluorescent labelling of
the membrane shows that this process is governed by continuous thinning
of the membrane up to the destabilization. It is likely that the
membrane shows a tran-sition from a solid to liquid state. At longer
times of complexation, the rupture has a feature of solid-like breakup
(breakage) with a discontinuity of the membrane. The maximal internal
constraint determined numerically marks the initial location of breakup
as shown. The pattern becomes more complex as the elon-gation rate
increases with several points of rupture. A phase diagram in the space
parameters of the shear elastic modulus and the hydrodynamic stress is
established.(c) 2022 Elsevier Inc. All rights reserved.
Xia, Ming; Record, Marie-Christine; Boulet, Pascal
Investigation of PbSnTeSe High-Entropy Thermoelectric Alloy: A DFT Approach Journal Article
In: MATERIALS, vol. 16, no. 1, 2023.
@article{WOS:000909958900001,
title = {Investigation of PbSnTeSe High-Entropy Thermoelectric Alloy: A DFT
Approach},
author = {Ming Xia and Marie-Christine Record and Pascal Boulet},
doi = {10.3390/ma16010235},
year = {2023},
date = {2023-01-01},
journal = {MATERIALS},
volume = {16},
number = {1},
abstract = {Thermoelectric materials have attracted extensive attention because they
can directly convert waste heat into electric energy. As a brand-new
method of alloying, high-entropy alloys (HEAs) have attracted much
attention in the fields of materials science and engineering. Recent
researches have found that HEAs could be potentially good thermoelectric
(TE) materials. In this study, special quasi-random structures (SQS) of
PbSnTeSe high-entropy alloys consisting of 64 atoms have been generated.
The thermoelectric transport properties of the highest-entropy
PbSnTeSe-optimized structure were investigated by combining calculations
from first-principles density-functional theory and on-the-fly machine
learning with the semiclassical Boltzmann transport theory and
Green-Kubo theory. The results demonstrate that PbSnTeSe HEA has a very
low lattice thermal conductivity. The electrical conductivity, thermal
electronic conductivity and Seebeck coefficient have been evaluated for
both n-type and p-type doping. N-type PbSnTeSe exhibits better power factor (PF = S-2 sigma) than p-type PbSnTeSe because of larger
electrical conductivity for n-type doping. Despite high electrical
thermal conductivities, the calculated ZT are satisfactory. The maximum
ZT (about 1.1) is found at 500 K for n-type doping. These results
confirm that PbSnTeSe HEA is a promising thermoelectric material.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
can directly convert waste heat into electric energy. As a brand-new
method of alloying, high-entropy alloys (HEAs) have attracted much
attention in the fields of materials science and engineering. Recent
researches have found that HEAs could be potentially good thermoelectric
(TE) materials. In this study, special quasi-random structures (SQS) of
PbSnTeSe high-entropy alloys consisting of 64 atoms have been generated.
The thermoelectric transport properties of the highest-entropy
PbSnTeSe-optimized structure were investigated by combining calculations
from first-principles density-functional theory and on-the-fly machine
learning with the semiclassical Boltzmann transport theory and
Green-Kubo theory. The results demonstrate that PbSnTeSe HEA has a very
low lattice thermal conductivity. The electrical conductivity, thermal
electronic conductivity and Seebeck coefficient have been evaluated for
both n-type and p-type doping. N-type PbSnTeSe exhibits better power factor (PF = S-2 sigma) than p-type PbSnTeSe because of larger
electrical conductivity for n-type doping. Despite high electrical
thermal conductivities, the calculated ZT are satisfactory. The maximum
ZT (about 1.1) is found at 500 K for n-type doping. These results
confirm that PbSnTeSe HEA is a promising thermoelectric material.