Wall-modeled large-eddy simulation of the flow past a rod-airfoil tandem by the Lattice Boltzmann method

Abstract

Purpose-The lattice Boltzmann (LB) method offers an alternative to conventional computational fluid dynamics (CFD) methods. However, its practical use for complex turbulent flows of engineering interest is still at an early stage. In this article, a LB wallmodeled large-eddy simulation (WMLES) solver is outlined. The flow past a rod-airfoil tandem in the sub-critical turbulent regime is examined as a challenging benchmark. Design/methodology/approach-Fluid dynamics are discretized upon the LB principles. The large-eddy simulation is accounted straightforwardly by including a modeled subgrid-scale viscosity in the LB scheme, whereas a wall-law model enforces the boundary condition at the first off-wall node. This physical modeling is briefly introduced and relevant references are given for details. The flow past a rod-airfoil tandem at Reynolds number Re = 4.8 × 10 4 and Mach number Ma 0.2 is simulated on a composite multiresolution grid; the numerical setup is detailed. Unsteady aerodynamic and aeroacoustic features including spectral analysis and far-field pressure fluctuations are discussed. Findings-Extensive quantitative comparisons with both experimental and numerical reference data indicate that aerodynamic and aeroacoustic features are well captured by the LB simulation. Originality/value-Our study shows that WMLES within the LB framework provides a workable and efficient alternative to Navier-Stokes CFD solvers in the context of complex turbulent flows. The LB method permits to access an attractive turnaround time while 1 preserving engineering accuracy.

Near Stall Unsteady Flow Responses to Morphing Flap Deflections

“…The promising bio-inspired concept of morphing structures is used on wings not only to optimize their shape during flight, but also to actively interact with the surrounding flow field in order to mitigate possible aerodynamic performance degradation, reduce the profile drag, delay onset of stall, or achieve early recovery from flow separation. However, there are many technical challenges in the integration of morphing configurations with an existing 'rigid' wing; one in particular is the difficulty of simulating and resolving the complex flow physics around morphing structures [4][5][6][7]. In addition, one would imagine the difficulty of finding the optimal morphing arrangements (e.g., frequency, amplitude, angle) whilst solving such numerically intensive simulations.…”

A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient

“…The Afzal's law has been compared to the dynamic wall model of Wang and Moin (2002) by Hou et al (2016) giving very similar results, better than those obtained using the equilibrium model of Spalding (1961), for the flow over a single cylinder and tandem cylinders which involve separation regions. An extended log-law taking adverse pressure gradient into account based on an Afzal-like law has been successfully applied to complex turbulent flows in Sengissen et al (2015), Lucas et al (2017) and Leveque et al (2018). As shown in Table 1, an equivalent explicit algebraic model extensively validated for pressure gradient boundary layers and separated flows is missing.…”

“…(3) has been validated by several authors. The wall model successfully used in Sengissen et al (2015), Lucas et al (2017) and Leveque et al (2018) to take adverse pressure gradient effect into account is based on the Afzal's law. It will be called Adverse Pressure Gradient Log-Law (APGLL) in this paper.…”

“…Large Eddy Simulation (LES) is well adapted to predict these unsteady and turbulent flows since the large scale structures influencing the flow are explicitly resolved when only the small dissipative scales are modelled (Sagaut 2006). LES is classically implemented within the Navier-Stokes framework but it can also be used with the Lattice Boltzmann Method (LBM) which is an emerging numerical method becoming popular in particular for subsonic aerodynamic flows and aeroacoustics prediction thanks to its low dissipative character (Marié et al 2009;Malaspinas and Sagaut 2012;Sengissen et al 2015;Lucas et al 2017;Leveque et al 2018;König et al 2018). The computational cost for wall-resolved LES (WRLES) on industrial configurations is however high due to the small grid size required near the wall to explicitly resolve the boundary layer dynamics (Piomelli 2008;Bose and Park 2018).…”

Low-Speed Turbofan Aerodynamic and Acoustic Prediction with an Isothermal Lattice Boltzmann Method

“…The Lattice Boltzmann Method (LBM) has emerged a few decades ago as an efficient alternative way to deal with Computational Fluid Dynamics (CFD) [1][2][3][4][5][6][7][8][9]. The study of complex fluid dynamic problems is usually done by solving the Navier-Stokes (NS) equations which describe the conservation of macroscopic quantities representing the fluid (mass, momentum and energy typically).…”