Divergence-free turbulence inflow conditions for large-eddy simulations with incompressible flow solvers

Abstract

Reynolds stresses, wall skin friction and power spectra of velocity fluctuations are compared with those obtained from using periodic inlet-outlet boundary conditions. In particular, the variances and power spectra of pressure fluctuations are shown to be accurately predicted only when the divergence-free * +44 (0)23 8059 4493Email address: z.xie@soton.ac.uk (Zheng-Tong Xie )

Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation

“…However, this approach tended to produce unrealistic pressure fluctuations as the mass flux entering the computational domain was not equal to the mass flux expected from the mean field. To resolve this a mass flux correction term from Kim et al (2013) and Poletto et al (2013) was applied to the flow field across the inlet, to reduce the pressure fluctuations to slightly above the laboratory case. The inlet jet had a mean velocity of 13:4ms À1 , with turbulence intensity of 17% and length scale of 0.11 (post-calculation), compared with respectively 13:4ms À1 , 16% and 0.1 from the experiments ).…”

Large-Eddy Simulations for Wind Turbine Blade: Dynamic Stall and Rotational Augmentation

“…The effect of freestream turbulence over a static airfoil is significant [5]. The effect of freestream turbulence on the flow over a pitching airfoil is reported here.…”

“…The number of grid points around the airfoil was increased by using a local refinement until the pressure and skin-friction were converged. The domain width was L z = 0.25c and the total number of cells was about 21×10 6 with 942 grid points along the airfoil surface and 128 points in the spanwise direction near the airfoil. The first off-wall grid point was placed at y 1 ≈ 7 × 10 −5 c. Averaging started once the lift coefficient reached a statistically converged state and the averaging was done over about 8T , where T = c/U ∞ ; the time step was t/T = 0.00015.…”

“…In particular, the effect of freestream turbulence on the dynamic stall hysteresis is studied by using the recently developed divergencefree turbulence inflow generation method [6]. Up to our knowledge, there is very little works on the effect of freestream turbulence on the dynamic stall characteristics and none with LES approaches.…”

Large-Eddy Simulation of an Urban Canopy Using a Synthetic Turbulence Inflow Generation Method

“…In this study a synthetic turbulence inflow generation method designed by Xie and Castro 1) and optimized by Kim et al 2) will be used to simulate an urban boundary layer over an array of cubes and one tall building in the center of the domain with noncyclic boundary conditions. The objective of this study is to show the advantages of using this synthetic turbulence inflow generator over a laminar inflow.…”