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⟩
Y. Feng, J. Miranda-Fuentes, Jérôme Jacob, Pierre Sagaut. Hybrid lattice Boltzmann model for atmospheric flows under anelastic approximation. Physics of Fluids, American Institute of Physics, 2021, 33 (3), pp.036607. ⟨10.1063/5.0039516⟩. ⟨hal-03326143⟩ Plus de détails...
Lattice Boltzmann (LB) method for atmospheric dynamics is developed by considering the characteristics of the anelastic approximation. After introducing reference base state values in atmospheric flows, an LB model, with an external force term, has been constructed in anelastic framework. In the proposed anelastic LB model, mass and momentum conservation equations are solved by the LB method with a regularization procedure, and temperature field or scalar transport is simulated by finite volume method. The derived macroscopic governing equations from the anelastic model are analyzed and discussed in Chapman-Enskog asymptotic expansion. The anelastic LB model is assessed considering three benchmarks including a non-hydrostatic atmospheric inviscid convection, two-dimensional density currents, and inertia-gravity waves in stably stratified atmospheric layer. The validations demonstrate that the anelastic extension of the LB method can simulate atmospheric flows effectively and accurately. Besides, the proposed model offers a unified framework for both Boussinesq approximation and anelastic approximation, which is largely free of characteristic depth of atmospheric flows.
Y. Feng, J. Miranda-Fuentes, Jérôme Jacob, Pierre Sagaut. Hybrid lattice Boltzmann model for atmospheric flows under anelastic approximation. Physics of Fluids, American Institute of Physics, 2021, 33 (3), pp.036607. ⟨10.1063/5.0039516⟩. ⟨hal-03326143⟩
Yongliang Feng, Johann Miranda‐fuentes, Shaolong Guo, Jérôme Jacob, Pierre Sagaut. ProLB: A Lattice Boltzmann Solver of Large‐Eddy Simulation for Atmospheric Boundary Layer Flows. Journal of Advances in Modeling Earth Systems, American Geophysical Union, 2021, 13 (3), pp.e2020MS002107. ⟨10.1029/2020MS002107⟩. ⟨hal-03326123⟩ Plus de détails...
A large-eddy simulation tool is developed for simulating the dynamics of atmospheric boundary layers (ABLs) using lattice Boltzmann method (LBM), which is an alternative approach for computational fluid dynamics and proved to be very well suited for the simulation of low-Mach flows. The equations of motion are coupled with the global complex physical models considering the coupling among several mechanisms, namely basic hydro-thermodynamics and body forces related to stratification, Coriolis force, canopy effects, humidity transport, and condensation. Mass and momentum equations are recovered by an efficient streaming, collision, and forcing process within the framework of LBM while the governing equations of temperature, liquid, and vapor water fraction are solved using a finite volume method. The implementation of wall models for ABL, subgrid models, and interaction terms related to multiphysic phenomena (e.g., stratification, condensation) is described, implemented, and assessed in this study. An immersed boundary approach is used to handle flows in complex configurations, with application to flows in realistic urban areas. Applications to both wind engineering and atmospheric pollutant dispersion are illustrated.
Yongliang Feng, Johann Miranda‐fuentes, Shaolong Guo, Jérôme Jacob, Pierre Sagaut. ProLB: A Lattice Boltzmann Solver of Large‐Eddy Simulation for Atmospheric Boundary Layer Flows. Journal of Advances in Modeling Earth Systems, American Geophysical Union, 2021, 13 (3), pp.e2020MS002107. ⟨10.1029/2020MS002107⟩. ⟨hal-03326123⟩
Journal: Journal of Advances in Modeling Earth 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⟩ 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⟩
S. Guo, Yongliang Feng, Jérôme Jacob, F. Renard, Pierre Sagaut. An efficient lattice Boltzmann method for compressible aerodynamics on D3Q19 lattice. Journal of Computational Physics, Elsevier, 2020, 418, pp.109570. ⟨10.1016/j.jcp.2020.109570⟩. ⟨hal-02960161⟩ Plus de détails...
An efficient lattice Boltzmann (LB) model relying on a hybrid recursive regularization (HRR) collision operator on D3Q19 stencil is proposed for the simulation of three-dimensional high-speed compressible flows in both subsonic and supersonic regimes. An improved thermal equilibrium distribution function on D3Q19 lattice is derived to reduce the complexity of correcting terms. A simple shock capturing scheme and an upwind biased discretization of correction terms are implemented for supersonic flows with shocks. Mass and momentum equations are recovered by an efficient streaming, collision and forcing process on D3Q19 lattice. Then a non-conservative formulation of the entropy evolution equation is used, that is solved using a finite volume method. The proposed method is assessed considering the simulation of i) 2D isentropic vortex convection, ii) 3D non-isothermal acoustic pulse, iii) 2D supersonic flow over a bump, iv) 3D shock explosion in a box, v) 2D vortex interaction with shock wave, vi) 2D laminar flows over a flat plate at Ma of 0.5, 1.0 and 1.5.
S. Guo, Yongliang Feng, Jérôme Jacob, F. Renard, Pierre Sagaut. An efficient lattice Boltzmann method for compressible aerodynamics on D3Q19 lattice. Journal of Computational Physics, Elsevier, 2020, 418, pp.109570. ⟨10.1016/j.jcp.2020.109570⟩. ⟨hal-02960161⟩
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2020, ⟨10.1007/s10494-020-00181-7⟩. ⟨hal-02960184⟩ Plus de détails...
A new explicit algebraic wall law for the Large Eddy Simulation of flows with adverse pressure gradient is proposed. This new wall law, referred as adverse pressure gradient power law (APGPL), is developed starting from the power-law of Werner and Wengle (Turbulent Shear Flows, vol 8, Springer, New York, pp 155-168, 1993) in order to mimic an implicit non-equilibrium log-law based on Afzal's law (Afzal, IUTAM Symposium on Asymptotic Methods for Turbulent Shear Flows at High Reynolds Numbers, Kluwer Academic Publishers, Bochum, pp 95-118, 1996). No iterative method is needed for the evaluation of the wall shear stress from the APGPL contrary to the majority of models available in the literature. The APGPL model relies on the definition of three modes: the equilibrium power-law is used in regions of no or favourable pressure gradient, the APGPL is used in regions of adverse pressure gradient, and no wall model is used in separated flow regions. This model is assessed via Large Eddy Simulations of flows involving adverse pressure gradient and boundary layer separation using the Lattice Boltzmann Method on uniform nested grids. The flow around a clean and iced NACA23012 airfoil at Reynolds numberRe=1.88 x 10(6) and the flow over the LAGOON landing gear at Re=1.59x10(6) are considered. Results are found in good agreement with those obtained by the non-equilibrium log-law and experimental and numerical data available in the literature.
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2020, ⟨10.1007/s10494-020-00181-7⟩. ⟨hal-02960184⟩
Y. Feng, S. Guo, J. Jacob, P. Sagaut. Grid refinement in the three-dimensional hybrid recursive regularized lattice Boltzmann method for compressible aerodynamics. Physical Review E , American Physical Society (APS), 2020, 101 (6), pp.063302. ⟨10.1103/PhysRevE.101.063302⟩. ⟨hal-02892273⟩ Plus de détails...
Grid refinement techniques are of paramount importance for computational fluid dynamics approaches relying on the use of Cartesian grids. This is especially true of solvers dedicated to aerodynamics, in which the capture of thin shear layers require the use of small cells. In this paper, a three-dimensional grid refinement technique is developed within the framework of hybrid recursive regularized lattice Boltzmann method (HRR-LBM) for compressible high-speed flows, which is an efficient collide-stream-type method on a compact D3Q19 stencil. The proposed method is successfully assessed considering several test cases, namely, an isentropic vortex propagating through transition interface, shock-vortex interaction with intersection between grid refinement interface and shock corrugation, and transonic flows over three-dimensional DLR-M6 wing with seven levels of grid refinement.
Y. Feng, S. Guo, J. Jacob, P. Sagaut. Grid refinement in the three-dimensional hybrid recursive regularized lattice Boltzmann method for compressible aerodynamics. Physical Review E , American Physical Society (APS), 2020, 101 (6), pp.063302. ⟨10.1103/PhysRevE.101.063302⟩. ⟨hal-02892273⟩
Y. Feng, S. Guo, J. Jacob, P. Sagaut. Grid refinement in the three-dimensional hybrid recursive regularized lattice Boltzmann method for compressible aerodynamics. Physical Review E , American Physical Society (APS), 2020, 101 (6), pp.063302. ⟨10.1103/PhysRevE.101.063302⟩. ⟨hal-03228997⟩ Plus de détails...
Grid refinement techniques are of paramount importance for computational fluid dynamics approaches relying on the use of Cartesian grids. This is especially true of solvers dedicated to aerodynamics, in which the capture of thin shear layers require the use of small cells. In this paper, a three-dimensional grid refinement technique is developed within the framework of hybrid recursive regularized lattice Boltzmann method (HRR-LBM) for compressible high-speed flows, which is an efficient collide-stream-type method on a compact D3Q19 stencil. The proposed method is successfully assessed considering several test cases, namely, an isentropic vortex propagating through transition interface, shock-vortex interaction with intersection between grid refinement interface and shock corrugation, and transonic flows over three-dimensional DLR-M6 wing with seven levels of grid refinement.
Y. Feng, S. Guo, J. Jacob, P. Sagaut. Grid refinement in the three-dimensional hybrid recursive regularized lattice Boltzmann method for compressible aerodynamics. Physical Review E , American Physical Society (APS), 2020, 101 (6), pp.063302. ⟨10.1103/PhysRevE.101.063302⟩. ⟨hal-03228997⟩
S. Guo, Yongliang Feng, Jérôme Jacob, F. Renard, Pierre Sagaut. An efficient lattice Boltzmann method for compressible aerodynamics on D3Q19 lattice. Journal of Computational Physics, Elsevier, 2020, 418, pp.109570. ⟨10.1016/j.jcp.2020.109570⟩. ⟨hal-03232070⟩ Plus de détails...
An efficient lattice Boltzmann (LB) model relying on a hybrid recursive regularization (HRR) collision operator on D3Q19 stencil is proposed for the simulation of three-dimensional high-speed compressible flows in both subsonic and supersonic regimes. An improved thermal equilibrium distribution function on D3Q19 lattice is derived to reduce the complexity of correcting terms. A simple shock capturing scheme and an upwind biased discretization of correction terms are implemented for supersonic flows with shocks. Mass and momentum equations are recovered by an efficient streaming, collision and forcing process on D3Q19 lattice. Then a non-conservative formulation of the entropy evolution equation is used, that is solved using a finite volume method. The proposed method is assessed considering the simulation of i) 2D isentropic vortex convection, ii) 3D non-isothermal acoustic pulse, iii) 2D supersonic flow over a bump, iv) 3D shock explosion in a box, v) 2D vortex interaction with shock wave, vi) 2D laminar flows over a flat plate at Ma of 0.5, 1.0 and 1.5.
S. Guo, Yongliang Feng, Jérôme Jacob, F. Renard, Pierre Sagaut. An efficient lattice Boltzmann method for compressible aerodynamics on D3Q19 lattice. Journal of Computational Physics, Elsevier, 2020, 418, pp.109570. ⟨10.1016/j.jcp.2020.109570⟩. ⟨hal-03232070⟩
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2020, 106 (1), pp.1-35. ⟨10.1007/s10494-020-00181-7⟩. ⟨hal-03231798⟩ Plus de détails...
A new explicit algebraic wall law for the Large Eddy Simulation of flows with adverse pressure gradient is proposed. This new wall law, referred as adverse pressure gradient power law (APGPL), is developed starting from the power-law of Werner and Wengle (Turbulent Shear Flows, vol 8, Springer, New York, pp 155-168, 1993) in order to mimic an implicit non-equilibrium log-law based on Afzal's law (Afzal, IUTAM Symposium on Asymptotic Methods for Turbulent Shear Flows at High Reynolds Numbers, Kluwer Academic Publishers, Bochum, pp 95-118, 1996). No iterative method is needed for the evaluation of the wall shear stress from the APGPL contrary to the majority of models available in the literature. The APGPL model relies on the definition of three modes: the equilibrium power-law is used in regions of no or favourable pressure gradient, the APGPL is used in regions of adverse pressure gradient, and no wall model is used in separated flow regions. This model is assessed via Large Eddy Simulations of flows involving adverse pressure gradient and boundary layer separation using the Lattice Boltzmann Method on uniform nested grids. The flow around a clean and iced NACA23012 airfoil at Reynolds numberRe=1.88 x 10(6) and the flow over the LAGOON landing gear at Re=1.59x10(6) are considered. Results are found in good agreement with those obtained by the non-equilibrium log-law and experimental and numerical data available in the literature.
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2020, 106 (1), pp.1-35. ⟨10.1007/s10494-020-00181-7⟩. ⟨hal-03231798⟩
Yongliang Feng, S. Guo, Jérôme Jacob, Pierre Sagaut. Solid wall and open boundary conditions in hybrid recursive regularized lattice Boltzmann method for compressible flows. Physics of Fluids, American Institute of Physics, 2019, 31 (12), pp.126103. ⟨10.1063/1.5129138⟩. ⟨hal-02467965⟩ Plus de détails...
Complex geometries and open boundaries have been intensively studied in the nearly incompressible lattice Boltzmann method (LBM) framework. Therefore, only few boundary conditions for the high speed fully compressible LBM have been proposed. This paper deals with the definition of efficient boundary conditions for the compressible LBM methods, with the emphasis put on the newly proposed hybrid recursive regularized D3Q19 LBM (HRR-LBM) with applications to compressible aerodynamics. The straightforward simple extrapolation-based far-field boundary conditions, the characteristic boundary conditions, and the absorbing sponge layer approach are extended and estimated in the HRR-LBM for the choice of open boundaries. Moreover, a cut-cell type approach to handle the immersed solid is proposed to model both slip and no-slip wall boundary conditions with either isothermal or adiabatic behavior. The proposed implementations are assessed considering the simulation of (i) isentropic vortex convection with subsonic to supersonic inflow and outflow conditions, (ii) two-dimensional (2D) compressible mixing layer, (iii) steady inviscid transonic flow over a National Advisory Committee for Aeronautics (NACA) 0012 airfoil, (iv) unsteady viscous transonic flow over a NACA 0012 airfoil, and (v) three-dimensional (3D) transonic flows over a German Aerospace Center (DLR) F6 full aircraft configuration.
Yongliang Feng, S. Guo, Jérôme Jacob, Pierre Sagaut. Solid wall and open boundary conditions in hybrid recursive regularized lattice Boltzmann method for compressible flows. Physics of Fluids, American Institute of Physics, 2019, 31 (12), pp.126103. ⟨10.1063/1.5129138⟩. ⟨hal-02467965⟩
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , American Physical Society (APS), 2019. ⟨hal-02265484⟩ Plus de détails...
An extended version of the hybrid recursive regularized Lattice-Boltzmann model which incorporates external force is developed to simulate humid air flows with phase change mechanisms under the Boussinesq approximation. Mass and momentum conservation equations are solved by a regu-larized lattice Boltzmann approach well suited for high Reynolds number flows, whereas the energy and humidity related equations are solved by a finite volume approach. Two options are investigated to account for cloud formation in atmospheric flow simulations. The first option considers a single conservation equation for total water and an appropriate invariant variable of temperature. In the other approach, liquid and vapor are considered via two separated equations, and phase transition is accounted for via a relaxation procedure. The obtained models are then systematically validated on four well-established benchmark problems including a double diffusive Rayleigh Bénard convection of humid air, 2D and 3D thermal moist rising bubble under convective atmospheric environment as well as a shallow cumulus convection in framework of large-eddy simulation.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , American Physical Society (APS), 2019. ⟨hal-02265484⟩
Lucie Merlier, Jérome Jacob, Pierre Sagaut. Lattice-Boltzmann large-eddy simulation of pollutant dispersion in complex urban environment with dense gas effect: Model evaluation and flow analysis. Building and Environment, Elsevier, 2019, 148, pp.634-652. ⟨10.1016/j.buildenv.2018.11.009⟩. ⟨hal-02176936⟩ Plus de détails...
The goal of this study is to assess the performance of an innovative Lattice Boltzmann (LB) - Large Eddy Simulation (LES) approach in simulating neutral and stratified pollutant dispersion in complex urban environments. Different simulations are performed for the central area of Paris, accounting for continuous neutral or non-neutral gas releases from a circular source located in both channeled or confined flows. Predicted concentrations are compared with detailed wind tunnel measurements from the MODITIC project (FFI, 2016). Results exhibit a good qualitative and quantitative agreement between numerical and experimental data for the different configurations studied. All the estimated quality metrics match acceptance criteria. In addition, it is shown that the new LBM LES approach is able to capture and highlight the key turbulent mechanisms underlying dispersion process in and above urban areas. Hence, being based on extensive and detailed simulations and quality assurance studies, this paper highlights that the developed approach is well suited to address urban dispersion issues, including accidental chemical releases and short term exposure problems. Such results are particularly valuable to support the design and use of fast response dispersion models.
Lucie Merlier, Jérome Jacob, Pierre Sagaut. Lattice-Boltzmann large-eddy simulation of pollutant dispersion in complex urban environment with dense gas effect: Model evaluation and flow analysis. Building and Environment, Elsevier, 2019, 148, pp.634-652. ⟨10.1016/j.buildenv.2018.11.009⟩. ⟨hal-02176936⟩
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, Elsevier, 2019, 394, pp.82-99. ⟨hal-02142837⟩ Plus de détails...
A thermal lattice Boltzmann model with a hybrid recursive regularization (HRR) collision operator is developed on standard lattices for simulation of subsonic and sonic compressible flows without shock. The approach is hybrid: mass and momentum conservation equations are solved using a lattice Boltzmann solver, while the energy conservation is solved under entropy form with a finite volume solver. The defect of Galilean invariance related to Mach number is corrected by the third order equilibrium distribution function , supplemented by an additional correcting term and hybrid recursive regularization. The proposed approach is assessed considering the simulation of i) an isentropic vortex convection, ii) a two dimensional acoustic pulse and iii) non-isothermal Gaussian pulse with Ma number in range of 0 to 1. Numerical simulations demonstrate that the flaw in Galilean invari-ance is effectively eliminated by the compressible HRR model. At last, the compressible laminar flows over flat plate at Ma number of 0.3 and 0.87, Reynolds number of 10 5 are considered to validate the capture of viscous and diffusive effects.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, Elsevier, 2019, 394, pp.82-99. ⟨hal-02142837⟩
Lucie Merlier, Jérôme Jacob, Pierre Sagaut. Lattice-Boltzmann Large-Eddy Simulation of pollutant dispersion in street canyons including tree planting effects. Atmospheric Environment, Elsevier, 2018, 195, pp.89-103. ⟨10.1016/j.atmosenv.2018.09.040⟩. ⟨hal-02114676⟩ Plus de détails...
This study assesses the performance of a large eddy simulation (LES) based on the lattice Boltzmann method (LBM) in predicting near field dispersion in street canyons with tree planting. Based on a benchmark test case benefiting from wind tunnel measurements (CODASC), this study qualitatively and quantitatively discusses the prediction of traffic-induced pollutant concentration with respect to several reference studies. It also analyses the physics of the flow and concentration fields. Although the problem might seem rather simple, the flow is highlighted to be strongly three dimensional and transient. These properties enhance pollutant dispersion in the empty street canyon but air flow velocity and turbulence intensity tend to decrease in tree crowns. This effect of trees increases both mean and peak concentration levels at pedestrian level, which may be problematic in cities with dense traffic. These results show that LBM-LES is particularly well suited to study dispersion problems towards the development of more breathable cities.
Lucie Merlier, Jérôme Jacob, Pierre Sagaut. Lattice-Boltzmann Large-Eddy Simulation of pollutant dispersion in street canyons including tree planting effects. Atmospheric Environment, Elsevier, 2018, 195, pp.89-103. ⟨10.1016/j.atmosenv.2018.09.040⟩. ⟨hal-02114676⟩
Jérôme Jacob, Orestis Malaspinas, Pierre Sagaut. A new hybrid recursive regularised Bhatnagar–Gross–Krook collision model for Lattice Boltzmann method-based large eddy simulation. Journal of Turbulence, Taylor & Francis, 2018, pp.1 - 26. ⟨10.1080/14685248.2018.1540879⟩. ⟨hal-02114308⟩ Plus de détails...
A new Lattice Boltzmann collision model for large eddy simulation (LES) of weakly compressible flows is proposed. This model, referred to as the Hybrid Recursive Regularised Bhatnagar-Gross-Krook (HRR-BGK) model, is based on a modification of previously existing regularised collision models defined with the BGK Lattice Boltzmann method (LBM) framework. By hybridising the computation of the velocity gradient with an adequate Finite Difference scheme when reconstructing the non-equilibrium parts of the distribution function , a hyperviscosity term is introduced in the momentum equation, whose amplitude can be explicitly tuned via a weighting parameter. A dynamic version of the HRR-BGK is also proposed, in which the control parameter is tuned at each grid point and each time step in order to recover an arbitrarily fixed total dissipation. This new collision model is assessed for both explicit and implicit LES considering the flow around a circular cylinder at Re = 3900. The dynamic HRR-BGK is observed to yield very accurate results when equipped with Vreman's subgrid model to compute the target dissipation.
Jérôme Jacob, Orestis Malaspinas, Pierre Sagaut. A new hybrid recursive regularised Bhatnagar–Gross–Krook collision model for Lattice Boltzmann method-based large eddy simulation. Journal of Turbulence, Taylor & Francis, 2018, pp.1 - 26. ⟨10.1080/14685248.2018.1540879⟩. ⟨hal-02114308⟩
Jérôme Jacob, Pierre Sagaut. Wind comfort assessment by means of large eddy simulation with lattice Boltzmann method in full scale city area. Building and Environment, Elsevier, 2018, 139, pp.110 - 124. ⟨10.1016/j.buildenv.2018.05.015⟩. ⟨hal-02114339⟩ Plus de détails...
Large-eddy simulations based on the Lattice-Boltzmann method of the flow in a realistic, full scale urban area are performed to compare several wind comfort criteria. It is observed that popular criteria for pedestrian comfort lead to very different conclusions, due to the access to high spatio-temporal resolution data. Different mixed strategies based on the combination of several criteria are proposed and compared to enhance pedestrian wind comfort assessment in practical cases.
Jérôme Jacob, Pierre Sagaut. Wind comfort assessment by means of large eddy simulation with lattice Boltzmann method in full scale city area. Building and Environment, Elsevier, 2018, 139, pp.110 - 124. ⟨10.1016/j.buildenv.2018.05.015⟩. ⟨hal-02114339⟩
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. An explicit power-law-based wall model for lattice Boltzmann method–Reynolds-averaged numerical simulations of the flow around airfoils. Physics of Fluids, American Institute of Physics, 2018, 30 (6), pp.065111. ⟨10.1063/1.5031764⟩. ⟨hal-02116210⟩ Plus de détails...
In this paper, an explicit wall model based on a power-law velocity profile is proposed for the simulation of the incompressible flow around airfoils at high Reynolds numbers. This wall model is particularly suited for the wall treatment involved in Cartesian grids. Moreover, it does not require an iterative procedure for the friction velocity determination. The validation of this power-law wall model is assessed for Reynolds-averaged Navier-Stokes simulations of the flow around a two-dimensional airfoil using the lattice Boltzmann approach along with the Spalart-Allmaras turbulence model. Good results are obtained for the prediction of the aerodynamic coefficients and the pressure profiles at two Reynolds numbers and several angles of attack. The explicit power-law is thus well suited for a simplified near-wall treatment at high Reynolds numbers using Cartesian grids.
Sylvia Wilhelm, Jérôme Jacob, Pierre Sagaut. An explicit power-law-based wall model for lattice Boltzmann method–Reynolds-averaged numerical simulations of the flow around airfoils. Physics of Fluids, American Institute of Physics, 2018, 30 (6), pp.065111. ⟨10.1063/1.5031764⟩. ⟨hal-02116210⟩
