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Performance of Turbulence Models in Simulating Wind Loads on Photovoltaics Modules
摘要： The performance of ?ve conventional turbulence models, commonly used in the wind industry, are examined in predicting the complex wake of an in?nite span thin normal ?at plate with large pressure gradients at Reynolds number of 1200. This body represents a large array of Photovoltaics modules, where two edges of the plate dominate the ?ow. This study provided a benchmark for capabilities of conventional turbulence models that are commonly used for wind forecasting in the wind energy industry. The results obtained from Reynolds Averaged Navier-Stokes (RANS) k ? ε, Reynolds Normalization Group (RNG) k ? ε, RANS k ? ω Shear Stress Transport (SST) and Reynolds Stress Model (RSM) were compared with existing Direct Numerical Simulations (DNS). The mean ?ow features and unsteady wake characteristics were used as testing criteria amongst these models. All turbulence models over-predicted the mean recirculation length and under-predicted the mean drag coef?cient. The major differences between numerical results in predicting the mean recirculation length, mean drag and velocity gradients, leading to de?cits in turbulence kinetic energy production and diffusion, hint at major dif?culties in modeling velocity gradients and thus turbulence energy transport terms, by traditional turbulence models. Unsteadiness of ?ow physics and nature of eddy viscosity approximations are potential reasons. This hints at the de?ciencies of these models to predict complex ?ows with large pressure gradients, which are commonly observed in wind and solar farms. The under-prediction of wind loads on PV modules and over-estimation of the recirculation length behind them signi?cantly affects the ef?ciency and operational feasibility of solar energy systems.
关键词： RANS,CFD,PV module,wake dynamics,turbulence,wind loads,wind forecasting
更新于2025-09-11 14:15:04
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Numerical Simulation of Focused Wave and Its Uncertainty Analysis
摘要： On the basis of the transient water wave (TWW) theory, focused wave is generated in the circulating water channel. Numerical simulation of the focused wave is carried out by solving the Reynolds averaged Navier-Stokes (RANS) equations. The dynamic grid technique is adopted to simulate the motion of the wave maker, and the volume of ?uid (VOF) method is used to capture the free surface of the wave. The simulation results are compared with the measured data, and good agreement is obtained. For quantitative estimation of the numerical simulation error and uncertainty, the uncertainty analysis method recommended by the International Towing Tank Conference (ITTC) procedure is performed for the simulation results of the surface elevations at di?erent positions. Both grid-convergence and time-step-size convergence studies are conducted using three types of grids and time step sizes. The simulation results are all monotonously convergent in the veri?cation procedure, and the validations of the simulated surface elevations with the positions at 3.5, 4.0 and 4.5 m are all achieved by comparing with the validation uncertainty. It is found that the numerical simulation errors caused by the grid and time-step-size in the convergence studies have the same order of magnitude. In addition, the numerical errors and uncertainties for the surface elevations at di?erent positions are compared and discussed in detail. This paper presents the ?rst attempt to carry out the uncertainty analysis of the simulation of focused wave, and the e?ectiveness of the proposed veri?cation and validation procedures in the uncertainty analysis is demonstrated.
关键词： Reynolds averaged Navier-Stokes (RANS) equations,validation,uncertainty analysis,veri?cation,focused wave
更新于2025-09-04 15:30:14