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Johan Degrigny, Shang-Gui Cai, Jean-François Boussuge, Pierre Sagaut. Improved wall model treatment for aerodynamic flows in LBM. Computers and Fluids, Elsevier, 2021, 227, pp.105041. ⟨10.1016/j.compfluid.2021.105041⟩. ⟨hal-03326170⟩ Plus de détails...
The article deals with an improved treatment of wall models for the simulation of turbulent flows in the framework of Immersed Wall Boundaries on Cartesian grids. The emphasis is put on the implementa-tion in a Lattice-Boltzmann Method solver without loss of generality, since the proposed approach can be used in Navier-Stokes-based solvers in a straightforward way. The proposed improved wall model im-plementation relies on the combination of several key elements, namely i) the removal of grid points too close to the solid surface and ii) an original computation of wall normal velocity gradient and iii) the interpolation scheme. The new method is successfully assessed considering URANS simulations focusing on steady solutions of the Zero Pressure Gradient turbulent flat plate boundary layer and the turbulent flow around a NACA0012 airfoil at several angles of attack.
Johan Degrigny, Shang-Gui Cai, Jean-François Boussuge, Pierre Sagaut. Improved wall model treatment for aerodynamic flows in LBM. Computers and Fluids, Elsevier, 2021, 227, pp.105041. ⟨10.1016/j.compfluid.2021.105041⟩. ⟨hal-03326170⟩
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, American Institute of Physics, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩ Plus de détails...
Giant unilamellar vesicles subjected to pulsed direct-current (pulsed-DC) fields are promising biomimetic systems to investigate the electroporation of cells. In strong electric fields, vesicles undergo significant deformation, which strongly alters the transmembrane potential, consequently the electroporation. Previous theoretical studies investigated the electrodeformation of vesicles in DC fields (which are not pulsed). In this work, we computationally investigate the deformation of a deflated vesicle under unipolar, bipolar, and two-step unipolar pulses and show sensitive dependence of intermediate shapes on type of pulse and the pulse width. Starting with the stress-free initial shape of a deflated vesicle, which is similar to a prolate spheroid, the analysis is presented for the cases with higher and lower conductivities of the inner fluid medium relative to the outer fluid medium. For the ratio of inner to outer fluid conductivity, σ r = 10, the shape always remains prolate, including when the field is turned off. For σ r = 0.1, several complex dynamics are observed, such as the prolate-to-oblate (PO), prolate-to-oblate-to-prolate (POP) shape transitions in time depending upon the strength of the field and the pulse properties. In this case, on turning off the field, a metastable oblate equilibrium shape is seen, that seems to be a characteristics of a deflated vesicle leading to POPO transitions. When a two-step unipolar pulse (a combination of a strong and a weak subpulse) is applied, a vesicle can reach an oblate or a prolate final shape depending upon the relative durations of the two subpulses. This study suggests that the transmembrane potential can be regulated using a bipolar pulsed-DC field. It also shows that the shapes admitted in the dynamics of a vesicle depends upon whether the pulse is unipolar or bipolar. Parameters are suggested wherein, the simulation results can be demonstrated in experiments.
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, American Institute of Physics, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩
Jérôme Jacob, Lucie Merlier, Felix Marlow, Pierre Sagaut. Lattice Boltzmann Method-Based Simulations of Pollutant Dispersion and Urban Physics. Atmosphere, MDPI 2021, 12 (7), pp.833. ⟨10.3390/atmos12070833⟩. ⟨hal-03326148⟩ Plus de détails...
Mesocale atmospheric flows that develop in the boundary layer or microscale flows that develop in urban areas are challenging to predict, especially due to multiscale interactions, multiphysical couplings, land and urban surface thermal and geometrical properties and turbulence. However, these different flows can indirectly and directly affect the exposure of people to deteriorated air quality or thermal environment, as well as the structural and energy loads of buildings. Therefore, the ability to accurately predict the different interacting physical processes determining these flows is of primary importance. To this end, alternative approaches based on the lattice Boltzmann method (LBM) wall model large eddy simulations (WMLESs) appear particularly interesting as they provide a suitable framework to develop efficient numerical methods for the prediction of complex large or smaller scale atmospheric flows. In particular, this article summarizes recent developments and studies performed using the hybrid recursive regularized collision model for the simulation of complex or/and coupled turbulent flows. Different applications to the prediction of meteorological humid flows, urban pollutant dispersion, pedestrian wind comfort and pressure distribution on urban buildings including uncertainty quantification are especially reviewed. For these different applications, the accuracy of the developed approach was assessed by comparison with experimental and/or numerical reference data, showing a state of the art performance. Ongoing developments focus now on the validation and prediction of indoor environmental conditions including thermal mixing and pollutant dispersion in different types of rooms equipped with heat, ventilation and air conditioning systems.
Jérôme Jacob, Lucie Merlier, Felix Marlow, Pierre Sagaut. Lattice Boltzmann Method-Based Simulations of Pollutant Dispersion and Urban Physics. Atmosphere, MDPI 2021, 12 (7), pp.833. ⟨10.3390/atmos12070833⟩. ⟨hal-03326148⟩
Pierre Boivin, M. Tayyab, S. Zhao. Benchmarking a lattice-Boltzmann solver for reactive flows: Is the method worth the effort for combustion?. Physics of Fluids, American Institute of Physics, 2021, 33 (7), pp.071703. ⟨10.1063/5.0057352⟩. ⟨hal-03276189⟩ Plus de détails...
Pierre Boivin, M. Tayyab, S. Zhao. Benchmarking a lattice-Boltzmann solver for reactive flows: Is the method worth the effort for combustion?. Physics of Fluids, American Institute of Physics, 2021, 33 (7), pp.071703. ⟨10.1063/5.0057352⟩. ⟨hal-03276189⟩
M. Bahlali, H. Yoo, Julien Favier, Pierre Sagaut. A lattice Boltzmann direct coupling overset approach for the moving boundary problem. Physics of Fluids, American Institute of Physics, 2021, 33 (5), pp.053607. ⟨10.1063/5.0044994⟩. ⟨hal-03326151⟩ Plus de détails...
We propose a new direct coupling scheme based on the overset technique to tackle moving boundary problems within the lattice Boltzmann framework. The scheme is based on the interpolation of distribution functions rather than moments, that is, macroscopic variables, and includes an additional hypothesis ensuring mass and momentum conservation at the interface nodes between fixed and moving grids. The method is assessed considering four test cases and considering both the vortical and the acoustic fields. It is shown that the direct coupling method results are in very good agreement with reference results on a configuration without any moving subdomain. Moreover, it is demonstrated that the direct coupling method provides an improvement of the accuracy of the lattice Boltzmann overset algorithm for aeroacoustics. In particular, a convected vortex test case is studied and reveals that the direct coupling approach leads to a better ability to conserve the vortex structure over time, as well as a reduction in spurious acoustic distorsions at the fixed/moving interface.
M. Bahlali, H. Yoo, Julien Favier, Pierre Sagaut. A lattice Boltzmann direct coupling overset approach for the moving boundary problem. Physics of Fluids, American Institute of Physics, 2021, 33 (5), pp.053607. ⟨10.1063/5.0044994⟩. ⟨hal-03326151⟩
H. Yoo, M. Bahlali, Julien Favier, Pierre Sagaut. A hybrid recursive regularized lattice Boltzmann model with overset grids for rotating geometries. Physics of Fluids, American Institute of Physics, 2021, 33 (5), pp.057113. ⟨10.1063/5.0045524⟩. ⟨hal-03326134⟩ Plus de détails...
Simulating rotating geometries in fluid flows for industrial applications remains a challenging task for general fluid solvers and in particular for the lattice Boltzmann method (LBM) due to inherent stability and accuracy problems. This work proposes an original method based on the widely used overset grids (or Chimera grids) while being integrated with a recent and optimized LBM collision operator, the hybrid recursive regularized model (HRR). The overset grids are used to actualize the rotating geometries where both the rotating and fixed meshes exist simultaneously. In the rotating mesh, the fictitious forces generated from its non-inertial rotating reference frame are taken into account by using a second order discrete forcing term. The fixed and rotating grids communicate with each other through the interpolation of the macroscopic variables. Meanwhile, the HRR collision model is selected to enhance the stability and accuracy properties of the LBM simulations by filtering out redundant higher order non-equilibrium tensors. The robustness of the overset HRR algorithm is assessed on different configurations, undergoing mid-to-high Reynolds number flows, and the method successfully demonstrates its robustness while exhibiting the second order accuracy.
H. Yoo, M. Bahlali, Julien Favier, Pierre Sagaut. A hybrid recursive regularized lattice Boltzmann model with overset grids for rotating geometries. Physics of Fluids, American Institute of Physics, 2021, 33 (5), pp.057113. ⟨10.1063/5.0045524⟩. ⟨hal-03326134⟩
Sébastien Clercq, Feral Temelli, Elisabeth Badens. In-Depth Study of Cyclodextrin Complexation with Carotenoids toward the Formation of Enhanced Delivery Systems. Molecular Pharmaceutics, American Chemical Society, 2021, 18 (4), pp.1720-1729. ⟨10.1021/acs.molpharmaceut.0c01227⟩. ⟨hal-03334353⟩ Plus de détails...
The goal of this study was molecular modeling of cyclodextrin (CD) and carotenoid complex formation. Distinction was made between complexes resulting from interactions between carotenoids and either molecularly dispersed CDs or solid crystalline CDs, considering that both cases can occur depending on the complex formation process pathways. First, the formation of complexes from dispersed CD molecules was investigated considering five different CDs (αCD, βCD, methyl-βCD, hydroxypropyl-βCD, and γCD) and lutein, as a model carotenoid molecule. The interactions involved and the stability of the different complexes formed were evaluated according to the CD size and steric hindrance. Second, the formation of complexes between four different crystalline CDs (βCD with three different water contents and methyl-βCD) and three carotenoid molecules (lutein, lycopene, and β-carotene) was studied. The docking/adsorption of the carotenoid molecules was modeled on the different faces of the CD crystals. The findings highlight that all the CD faces, and thus their growth rates, were equally impacted by the adsorption of the carotenoids. This is due to the fact that all the CD faces are exhibiting similar chemical compositions, the three studied carotenoid molecules are rather chemically similar, and last, the water–carotenoid interactions appear to be weak compared to the CD–carotenoid interactions.
Sébastien Clercq, Feral Temelli, Elisabeth Badens. In-Depth Study of Cyclodextrin Complexation with Carotenoids toward the Formation of Enhanced Delivery Systems. Molecular Pharmaceutics, American Chemical Society, 2021, 18 (4), pp.1720-1729. ⟨10.1021/acs.molpharmaceut.0c01227⟩. ⟨hal-03334353⟩
Florian Renard, Yongliang Feng, Jean-François Boussuge, Pierre Sagaut. Improved compressible hybrid lattice Boltzmann method on standard lattice for subsonic and supersonic flows. Computers and Fluids, Elsevier, 2021, 219, pp.104867. ⟨10.1016/j.compfluid.2021.104867⟩. ⟨hal-03326159⟩ Plus de détails...
A D2Q9 Hybrid Lattice Boltzmann Method (HLBM) is proposed for the simulation of both compressible subsonic and supersonic flows. This HLBM is an extension of the model of Feng et al. [1], which has been found, via different test cases, to be unstable for supersonic regimes. To circumvent this limitation, we propose:: (1) a new discretization of the lattice closure correction term that makes possible the simulation of supersonic flows, (2) a corrected viscous stress tensor that takes into account polyatomic gases, and (3) a novel discretization of the viscous heat production term fitting with the regularized formalism. The result is a hybrid method that resolves the mass and momentum equations with an LBM algorithm, and resolves the entropy-based energy equation with a finite volume method. This approach fully recovers the physics of the Navier-Stokes-Fourier equations with the ideal gas equation of state, and is valid from subsonic to supersonic regimes. It is then successfully assessed with both smooth flows and flows involving shocks. The proposed model is shown to be an efficient, accurate, and robust alternative to classic Navier-Stokes methods for the simulation of compressible flows.
Florian Renard, Yongliang Feng, Jean-François Boussuge, Pierre Sagaut. Improved compressible hybrid lattice Boltzmann method on standard lattice for subsonic and supersonic flows. Computers and Fluids, Elsevier, 2021, 219, pp.104867. ⟨10.1016/j.compfluid.2021.104867⟩. ⟨hal-03326159⟩
Mathieu Martino, Adil Mouahid, Paolo Trucillo, Elisabeth Badens. Elaboration of Lutein‐Loaded Nanoliposomes Using Supercritical CO2. European Journal of Lipid Science and Technology, Wiley-VCH Verlag, 2021, 123 (4), pp.2000358. ⟨10.1002/ejlt.202000358⟩. ⟨hal-03334357⟩ Plus de détails...
A batch process for producing lutein-loaded liposomes using supercritical CO2 is studied. The effects of the variation of pressure (10 and 15 MPa), temperature (308, 313, and 318 K), and lutein to lipid ratio (0.5 and 1 wt%) on the liposome average size and size distribution are investigated, as well as on the encapsulation efficiency (EE) of lutein. This process is worked in a repeatable manner and is allowed the production of nanoliposomes with mean diameters (MDs) ranging from 65 ± 33 to 77 ± 40 nm, obtaining lutein EEs ranging from 82.1 ± 3.7% to 91.9 ± 2.9%. Temperature, pressure, and lutein to lipid ratio seem to have no impact on size, size distribution, and EE on formed liposomes. The use of low temperatures and low pressures allows the obtainment of liposomes with diameters less than 100 nm and limits the process energy cost. Moreover, the supercritical CO2-assisted batch process effectively encapsulates lutein into liposome, an antioxidant molecule used for the prevention of retinal damage. Liposomes formed by this supercritical process have the desired characteristics for human target delivery. Practical applications: This work on the optimization of a process for developing liposomes in a supercritical environment has applications in medicine. Indeed, the liposomes formed with this process are nanoliposomes with a size of less than 80 nm. In addition, excellent lutein EEs (hydrophobic molecules) show that the liposomes formed constitute excellent coating matrices for the protection of active ingredients. These reasons make these liposome matrices applicable in nanomedicine (injection of sensitive drugs requiring protection before injection). The elaboration process also makes it possible to form liposomes with desired properties by changing pressure, temperature, or lecithin concentration. Therefore, this work focuses on the properties of liposomes as a function of the operating conditions.
Mathieu Martino, Adil Mouahid, Paolo Trucillo, Elisabeth Badens. Elaboration of Lutein‐Loaded Nanoliposomes Using Supercritical CO2. European Journal of Lipid Science and Technology, Wiley-VCH Verlag, 2021, 123 (4), pp.2000358. ⟨10.1002/ejlt.202000358⟩. ⟨hal-03334357⟩
Journal: European Journal of Lipid Science and Technology
Jérémie Janin, Fabien Duval, Christophe Friess, Pierre Sagaut. A new linear forcing method for isotropic turbulence with controlled integral length scale. Physics of Fluids, American Institute of Physics, 2021, 33 (4), pp.045127. ⟨10.1063/5.0045818⟩. ⟨hal-03326165⟩ Plus de détails...
Turbulence is a common feature to all flows that surround us. Despite its ubiquity, particularly in industrial flows, it is very difficult to provide a mathematical framework for the generation of turbulent eddies. Several methods have been proposed which are able to reproduce realistic features for velocity fluctuations, exhibiting proper space- and time-correlations. Focusing on physical space forcing, these methods are usually first evaluated upon sustained homogeneous isotropic turbulence by introducing a body force to the Navier-Stokes equations. Since the pioneering work of Lundgren, these techniques usually experience difficulties in predicting the integral length scale. The present study provides a forcing through a reconstruction approach which consists in building velocity fluctuations with a prescribed energy spectrum model. The proposed approach is assessed by performing large-eddy simulations of a sustained homogeneous isotropic turbulence in a triply periodic box. Properties of this forcing technique are discussed, drawing on both spatial and time correlations and also on the shape of energy spectrum together with the level of resolved turbulent kinetic energy. A special attention is put on the control of resolved turbulent energy. In this framework, an efficient selective forcing technique is derived, making use of spectral space features. The results show that the proposed approach allows to drive efficiently the resolved kinetic energy toward its target value while preserving the integral length scale independent of the domain size. It is observed that the resulting longitudinal length scale is overestimated by 13%, while the two-time correlations are recovered when using stochastic frequencies.
Jérémie Janin, Fabien Duval, Christophe Friess, Pierre Sagaut. A new linear forcing method for isotropic turbulence with controlled integral length scale. Physics of Fluids, American Institute of Physics, 2021, 33 (4), pp.045127. ⟨10.1063/5.0045818⟩. ⟨hal-03326165⟩
