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![Supersonic flow past a 2D NACA0012 airfoil at (Ma, Re) = (1.5, 104) with a simulation domain [10C, 10C] discretized using 200 points per chord C. Right: Mach number; Left: Mesh computed using the proposed criterion. The finest level corresponds to a resolution of 1/(10C). More details about the compressible LBM used for this test can be found in Ref. [50].](profile/Christophe-Coreixas-2/publication/363638255/figure/fig2/AS:11431281085416274@1663760832386/Supersonic-flow-past-a-2D-NACA0012-airfoil-at-Ma-Re-15-104-with-a-simulation.png)
Supersonic flow past a 2D NACA0012 airfoil at (Ma, Re) = (1.5, 104) with a simulation domain [10C, 10C] discretized using 200 points per chord C. Right: Mach number; Left: Mesh computed using the proposed criterion. The finest level corresponds to a resolution of 1/(10C). More details about the compressible LBM used for this test can be found in Ref. [50].
Source publication
A novel mesh refinement sensor is proposed for lattice Boltzmann methods (LBMs) applicable to either static or dynamic mesh refinement algorithms. The sensor exploits the kinetic nature of LBMs by evaluating the departure of distribution functions from their local equilibrium state. This sensor is first compared, in a qualitative manner, to three s...
Citations
... In this presentation, we focus on the key requirements for the design of compressible LBMs dedicated to industrial applications. Specifically, we summarize our recent research which aims to satisfy a number of requirements for realistic overnight simulations: (1) trade-off between accuracy/robustness/efficiency [1-3], (2) turbulence and wall modeling [4,5], (3) hardware-agnostic and easily maintainable solver [6-10], and (4) adaptive mesh refinement in velocity and geometric space [2,[8][9][10][11]. Figure 1: Illustration of adaptive mesh refinement in space for compressible LBMs. The grid is dynamically computed thanks to the kinetic sensor [11], and data obtained from the supersonic flow past a NACA airfoil at Ma = 1.5 and Re = ×10 4 [1]. ...
Talk about requirements to develop an accurate, robust and efficient compressible LBM for industrial applications, as well as, the corresponding work that was done at the University of Geneva in collaboration with SUSTech and NVIDIA.
... (1) tradeoff between accuracy/robustness/efficiency [1][2][3], (2) turbulence and wall modeling [4,5], (3) hardware-agnostic and easily maintainable solver [6][7][8][9][10], and (4) adaptive mesh refinement in velocity and geometric space [2,[8][9][10][11]. The grid is dynamically computed thanks to the kinetic sensor [11], and data obtained from the supersonic flow past a NACA airfoil at M = 1.5 and Re = 10 4 [1]. ...
... (1) tradeoff between accuracy/robustness/efficiency [1][2][3], (2) turbulence and wall modeling [4,5], (3) hardware-agnostic and easily maintainable solver [6][7][8][9][10], and (4) adaptive mesh refinement in velocity and geometric space [2,[8][9][10][11]. The grid is dynamically computed thanks to the kinetic sensor [11], and data obtained from the supersonic flow past a NACA airfoil at M = 1.5 and Re = 10 4 [1]. Left: Grid visualization. ...
... 11.1 2D GPU simulations of (top) flow around an 30P30N airfoil in high-lift configuration at M = 0.17 and Re = 1.71 × 10 11.2 Cavity 2D example with different meshes ...
Lattice Boltzmann Methods (LBM) or Thermal Lattice Boltzmann Methods (TLBM) is a CFD methods for fluid simulation. Instead of solving the Navier–Stokes equations, the discrete Boltzmann equation is solved to simulate the flow of a Newtonian fluid with collision models such as Bhatnagar–Gross–Krook (BGK). By simulating streaming and collision processes across a limited number of particles, the intrinsic particle interactions evince a microcosm of viscous flow behavior applicable across the greater mass. It is a modern approach in Computational Fluid Dynamics and often used to solve the in compressible, time-dependent Navier-Stokes equations numerically. Its strength lies however in the ability to easily represent complex physical phenomena, ranging from multiphase flows to chemical interactions between the fluid and the surroundings.
... On-going work on GPU-accelerated adap4ve mesh refinement in space [1] for compressible LBMs with a kine4c-based sensor [2] ...
Lattice Boltzmann methods (LBMs) are well-established alternative solutions to Navier-Stokes-Fourier (NSF) solvers for the simulation of isothermal and weakly compressible flows past realistic geometries. Nevertheless, fully compressible LBMs have difficulties competing with NSF solvers due to an increased size of the lattice required to get the correct macroscopic behavior, and/or complexity of the numerical scheme to ensure stable simulations. This is especially true since industry-oriented compressible LB solvers do not benefit from hardware acceleration (e.g., GPUs), unlike a number of academic and commercial solvers based on NSF equations.
In this presentation, we focus on the key requirements for the design of compressible LBMs dedicated to industrial applications. Specifically, we summarize recent research at the University of Geneva, which aims to satisfy a number of requirements for realistic overnight simulations: (1) trade-off between accuracy/robustness/efficiency, (2) turbulence and wall modeling, (3) hardware-agnostic and easily maintainable solver, and (4) adaptive mesh refinement in velocity and geometric space.
A family of positivity-preserving lattice Boltzmann methods (LBMs) is proposed for compressible flow simulations in the continuum regime. It relies on the efficient collide-and-stream algorithm with a collision step based on exponential distribution functions. The latter serves as a generalization of Grad's post-collision distribution functions for which here (1) the linearized non-equilibrium contributions are replaced by their exponential forms and (2) the number of these contributions can be chosen arbitrary. In practice, post-collision moments of our exponential formulation are enforced through an iterative moment-matching approach to recover any macroscopic physics of interest, with or without external forces. This methodology directly flows from the extended framework on numerical equilibria [J. Latt et al., Philos. Trans. R. Soc. A 378, 20190559 (2020)] and goes one step further by allowing for the independent relaxation of hydrodynamic and high-order modes in a given moment space, notably, making the Prandtl number freely adjustable. The model is supplemented by a shock-capturing technique, based on the deviation of non-equilibrium moments from their equilibrium counterparts, to ensure good numerical properties of the model in inviscid and under-resolved conditions. A second exponential distribution accounts for extra degrees of freedom of molecules and allows for the simulation of polyatomic gases. To validate this novel approach and to quantify the accuracy of different lattices and moment closures, several 2D benchmark tests of increasing complexity are considered: double shear layer, linear wave decay, Poiseuille flow, Riemann problem, compressible Blasius flow over a flat plate, and supersonic flow past an airfoil. Corresponding results confirm the accuracy and stability properties of our approach for the simulation of compressible flows with LBMs. Eventually, the performance analysis further highlights its efficiency on general purpose graphical processing units.
