Large-eddy lattice-Boltzmann modeling of transonic flows
TL;DR: In this paper, a hybrid recursive regularized pressure based lattice Boltzmann method (HRR-P LBM) is assessed for the simulation of complex transonic flows, where Mass and momentum conservation equations are resolved through a classical LBM solver coupled with a finite volume resolution of entropy equation for a complete compressible solver preserving stability, accuracy, and computational costs.
Abstract: A D3Q19 hybrid recursive regularized pressure based lattice-Boltzmann method (HRR-P LBM) is assessed for the simulation of complex transonic flows. Mass and momentum conservation equations are resolved through a classical LBM solver coupled with a finite volume resolution of entropy equation for a complete compressible solver preserving stability, accuracy, and computational costs. An efficient treatment for wall and open boundaries is coupled with a grid refinement technique and extended to the HRR-P LBM in the scope of compressible aerodynamics. A Vreman subgrid turbulence model and an improved coupling of immersed boundary method with turbulence wall model on Cartesian grid accounts for unresolved scales by large-eddy simulation. The validity of the present method for transonic applications is investigated through various test cases with increasing complexity starting from an inviscid flow over a 10% bump and ending with a turbulent flow over a ONERA M6 three-dimensional wing.
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TL;DR: In this article , pressure-based hybrid lattice-Boltzmann method is assessed for the simulation of buoyancy driven flows and a large-eddy simulation of a turbulent forced plume is then carried out, and results are validated against experiments.
Abstract: The pressure-based hybrid lattice-Boltzmann method presented by Farag & al (Phys. Fluids 2020) is assessed for the simulation of buoyancy driven flows. The model is first validated on Rayleigh-Benard and Rayleigh-Taylor two-dimensional cases. A large-eddy simulation of a turbulent forced plume is then carried out, and results are validated against experiments. A good overall agreement is obtained, both for mean and fluctuations quantities, as well as global entertainment. The self-similarity character of the plume in the far-field is also recovered.
2 citations
TL;DR: In this article , the authors used recursive regularized thermal lattice Boltzmann method (RR-TLBM) to reveal the near-wall vortices and the effects of flow states in coupled-domain transpiration cooling using a desktop-level computer with CUDA 11.6.
Abstract: The present study aims to reveal the near-wall vortices and the effects of flow states in coupled-domain transpiration cooling using a recursive regularized thermal lattice Boltzmann method (RR-TLBM). Large-eddy simulations of turbulent flow and heat transfer have been conducted on high-resolution computational grids using a desktop-level computer with CUDA 11.6. Results indicate that the near-wall flow structures present spatial characteristics along the streamwise direction. The vortex evolution promotes the downstream heat dissipation, even though turbulence impairs the effective cooling area. The spanwise evolvement of vortices strengthens the mixing of coolant and hot gas, and small-scale structures are beneficial for turbulent heat transfer. Moreover, the transition onset occurs earlier at higher Reynolds numbers, and it weakens the downstream cooling. The cooling performance of the derived coolant film is improved as the Reynolds number varies from 5 × 103 to 3 × 104 with a blowing ratio of F = 10%, whereas the local cooling is impaired at the high Reynolds numbers exceeding 5 × 104. The variation in flow states has little influence on the cooling performance at the Reynolds numbers larger than 3 × 106. On the other hand, our in-house RR-TLBM solver is highly stable and efficient for the simulation of flow and heat transfer with high Reynolds numbers. Simultaneously, a high computational performance of 1127 million lattices updated per second is achieved for our simulation of a coupled-domain turbulent flow and heat transfer, using the desktop-level computer with three Tesla V100 graphics processing units.
2 citations
TL;DR: In this article , a hybrid grid refinement method is proposed for the near-wall region of the grid, which comprises the reconstruction algorithm in refined nearwall nodes on the refinement interface and the in-domain interpolation multi-grid method to prevent the distortion of the pseudo-wall among resolution levels.
Abstract: The recent development of the lattice Boltzmann method enables its widespread application in various industrial areas. However, in the simulation of complicated industrial problems, considerable grid numbers are required to achieve reasonable resolution in the near-wall region due to the lack of a local refinement method on the geometry. This study proposes a new hybrid grid refinement method, which comprises the reconstruction algorithm in refined near-wall nodes on the refinement interface and the in-domain interpolation multi-grid method to prevent the local distortion of the pseudo-wall among resolution levels. The proposed method is validated on a two-dimensional flat plate and NACA0012 airfoil at low and high Reynolds numbers. Furthermore, the aerodynamic and aeroacoustics of a pair of counter-rotating propellers are simulated with the proposed lattice Boltzmann method and compared with the results obtained using commercial software.
1 citations
TL;DR: In this paper , a low-Mach algorithm based on thermal Lattice Boltzmann method (LBM) is proposed aiming at reducing the computational cost of thermal flow simulations in low Mach number limit.
Abstract: A new low-Mach algorithm based on thermal Lattice Boltzmann method (LBM) is proposed aiming at reducing the computational cost of thermal flow simulations in low Mach number limit.Considering the time-step restriction of fully compressible solvers, the Low Mach Number Approximation (LMNA) allows to accelerate significantly the simulations by re-scaling the acoustic speed to the same order of the velocity of the fluid motion when calculating the time-step.The proposed method is inspired by the similarity between the artificial compressibility method and isothermal LBM, and is further extended to thermal counterpart.It must be emphasized that this kind of low-Mach acceleration strategy is a general form and can be easily applied to other thermal LB methods.The present method overcomes the drawback of classical PGS (Pressure Gradient Scaling) method due to the pressure gradient changing. The new algorithm is validated by benchmarking the code on various well-documented academic test cases in laminar (1D gravity column, 2D rising thermal bubble, 2D differentially heated square cavity) and turbulent (Taylor Green Vortex and 3D heated cylinder) regimes.All the results show excellent agreement with reference data of the literature and demonstrate high computational efficiency.
1 citations
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TL;DR: In this paper, a kinetic theory approach to collision processes in ionized and neutral gases is presented, which is adequate for the unified treatment of the dynamic properties of gases over a continuous range of pressures from the Knudsen limit to the high pressure limit where the aerodynamic equations are valid.
Abstract: A kinetic theory approach to collision processes in ionized and neutral gases is presented. This approach is adequate for the unified treatment of the dynamic properties of gases over a continuous range of pressures from the Knudsen limit to the high-pressure limit where the aerodynamic equations are valid. It is also possible to satisfy the correct microscopic boundary conditions. The method consists in altering the collision terms in the Boltzmann equation. The modified collision terms are constructed so that each collision conserves particle number, momentum, and energy; other characteristics such as persistence of velocities and angular dependence may be included. The present article illustrates the technique for a simple model involving the assumption of a collision time independent of velocity; this model is applied to the study of small amplitude oscillations of one-component ionized and neutral gases. The initial value problem for unbounded space is solved by performing a Fourier transformation on the space variables and a Laplace transformation on the time variable. For uncharged gases there results the correct adiabatic limiting law for sound-wave propagation at high pressures and, in addition, one obtains a theory of absorption and dispersion of sound for arbitrary pressures. For ionized gases the difference in the nature of the organization in the low-pressure plasma oscillations and in high-pressure sound-type oscillations is studied. Two important cases are distinguished. If the wavelengths of the oscillations are long compared to either the Debye length or the mean free path, a small change in frequency is obtained as the collision frequency varies from zero to infinity. The accompanying absorption is small; it reaches its maximum value when the collision frequency equals the plasma frequency. The second case refers to waves shorter than both the Debye length and the mean free path; these waves are characterized by a very heavy absorption.
6,627 citations
TL;DR: An overview of the lattice Boltzmann method, a parallel and efficient algorithm for simulating single-phase and multiphase fluid flows and for incorporating additional physical complexities, is presented.
Abstract: We present an overview of the lattice Boltzmann method (LBM), a parallel and efficient algorithm for simulating single-phase and multiphase fluid flows and for incorporating additional physical complexities. The LBM is especially useful for modeling complicated boundary conditions and multiphase interfaces. Recent extensions of this method are described, including simulations of fluid turbulence, suspension flows, and reaction diffusion systems.
6,565 citations
TL;DR: In this article, a boundary condition formulation for the Navier-Stokes equations is proposed, which is compatible with non-disjoint algorithms applicable to direct simulations of turbulent flows.
3,214 citations
TL;DR: In this article, an eddy-viscosity model is proposed and applied in large-eddy simulation of turbulent shear flows with quite satisfactory results, which is essentially not more complicated than the Smagorinsky model, but is constructed in such a way that its dissipation is relatively small in transitional and near-wall regions.
Abstract: An eddy-viscosity model is proposed and applied in large-eddy simulation of turbulent shear flows with quite satisfactory results. The model is essentially not more complicated than the Smagorinsky model, but is constructed in such a way that its dissipation is relatively small in transitional and near-wall regions. The model is expressed in first-order derivatives, does not involve explicit filtering, averaging, or clipping procedures, and is rotationally invariant for isotropic filter widths. Because of these highly desirable properties the model seems to be well suited for engineering applications. In order to provide a foundation of the model, an algebraic framework for general three-dimensional flows is introduced. Within this framework several types of flows are proven to have zero energy transfer to subgrid scales. The eddy viscosity is zero in the same cases; the theoretical subgrid dissipation and the eddy viscosity have the same algebraic structure. In addition, the model is based on a fundament...
1,003 citations
TL;DR: A local second-order grid refinement scheme for the lattice?BGK model is proposed and a boundary-fitting scheme for complicated geometries are applied to simulate a benchmark problem of flow past a cylinder in a channel with small and moderate Reynolds numbers.
617 citations