Numerical study of aerodynamic characteristics of a square prism in a uniform flow

Aerodynamic characteristics of a square prism in a uniform flow for various angles of attack have been investigated using LES turbulence model. The results show that mean aerodynamic coefficients, surface pressures, and flow patterns for all angles of attack agree favorably with experiments. In addition, spanwise length of computational domain is found to slightly influence the mean aerodynamic coefficients whereas it shows strong impacts on fluctuating aerodynamic coefficients, which motivates a development of grid-independent estimation method for quantitative evaluations of fluctuations. The predicted power spectral densities for fluctuating aerodynamic coefficients are in good agreements with experiments in primary frequencies, which can be explained by the flow patterns. Strouhal numbers obtained from the simulations also agree well with experiments and acute change observed around 14° is successfully captured. Finally, a method for estimating grid-independent fluctuating aerodynamic coefficients is proposed by using a systematic elongation of spanwise length and is validated by the numerical tests.