STUDY ON EVOLUTION CHARACTERISTICS OF ISOTROPIC TURBULENCE PASSING THROUGH A NORMAL SHOCK WAVE

Shock-turbulence interaction is a kind of important fundamental problem in aerodynamics. Based on solver Helios which applies cell-centered finite difference method (CCFDM), using fifth-order weighted compact nonlinear scheme (WCNS), we conducted direct numerical simulation (DNS) of the situation where isotropic turbulence passes through a normal shock wave. Turbulence statistics are calculated for analysis. We found after shock, density is a little lower than its non-turbulent value, so do temperature and pressure, on the contrary, longitudinal velocity is a little higher than its non-turbulent value. The commonality is that they all show an overshoot immediately behind the shock, after that they gradually approach towards their non-turbulent values along with downstream distance. Longitudinal Reynolds stress suffers a sudden decrease and increases rapidly followed by decaying. This evolution characteristics is captured in linear interaction analysis (LIA) and a transfer of energy from acoustical to vertical modes behind the shock is thought to be accounted for it according to this analysis. Different from longitudinal Reynolds stress, Transverse Reynolds stress suffers a sudden increase then decay monotonically. Anisotropy of Reynolds stress is apparent after shock, and it gradually increases as downstream distance increases. Turbulent kinetic energy suddenly increases and then evolves non-monotonically. Taylor microscale and Kolmogorov scales apparently decrease after shock, indicating the decrease of turbulent length scales, which leads to a requirement of higher resolution of mesh in this zone to solve the flow field. After shock, the root-mean-squares of density, temperature and pressure fluctuations are enhanced, and intensities of density and pressure decrease while intensity of temperature increases.