CFC 2025

Wall Modelled Large Eddy Simulation Approach with Incompressible Homogenized Lattice Boltzmann Method Using OpenLB

  • Bukreev, Fedor (Lattice Boltzmann Research Group KIT)
  • Kummerländer, Adrian (Lattice Boltzmann Research Group KIT)
  • Ito, Shota (Lattice Boltzmann Research Group KIT)
  • Krause, Mathias (Lattice Boltzmann Research Group KIT)

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The Lattice Boltzmann Method (LBM) is well-suited for processing large computational meshes with cell sizes tailored for Large Eddy Simulations (LES), making it an ideal choice for simulating highly turbulent flows in practical applications. LES requires accurate wall modeling in boundary cells to properly replicate the velocity profiles of boundary layers and the associated pressure distribution. Moreover, modern Computational Fluid Dynamics (CFD) often involves simulating moving objects, where transient motion directly influences the surrounding fluid flow. In the OpenLB framework~\cite{OpenLB}, the Homogenized LBM (HLBM) approach is employed to represent the movement of resolved objects within the computational domain. HLBM uses a single structured mesh, simplifying the algorithm and reducing computational overhead. For fluid-structure interaction, an efficient GPU-compatible implementation is demonstrated by Kummerländer et al. In turbulent flow LBM simulations, stable behavior can be achieved through various strategies, one of them the Hybrid Recursive Regularized (HRR) collision approach. Wall modeling in LBM presents unique challenges due to the need for population reconstruction in boundary cells. Here, the equilibrium population is reconstructed using the velocity derived from the wall function, while the non-equilibrium population, critical for velocity gradient calculations, is obtained from the stress tensor computed via the Finite Differences Method (FDM)~\cite{wm}. The velocity values required for FDM are also derived from the wall function. This work employs the Spalding wall function combined with Newton's method for iterative approximation of the turbulent friction velocity $u_{\tau}$ and $u+$. We demonstrate the integration of this wall modeling approach within HLBM using the HRR collision model. The methodology is applied to various case studies, including turbulent channel flow, a stirred tank, and a centrifugal pump, showcasing its efficacy and practical utility.