Anisotropic pressure and acceleration spectra in uniform shear flow
Seminar Room 1, Newton Institute
According to the local isotropic hypothesis, the small scale physical quantities such as velocity, temperature and pressure fluctuations are to be universal in any kind of turbulent flow. At this stage, the question is not whether this assumption is correct or not, but seems to be how the large scale anisotropy lost its information as the scale becomes small. In this talk, the anisotropic effect on inertial-range quantities are directly checked following the formula presented by Ishihara, Yoshida and Kaneda (P.R.L.,vol.88,154501,2002), in which the velocity correlation spectrum was uniquely determined by the rate of strain tensor of mean flow, the energy dissipation of per unit mass, and the two-non dimensional constants. This idea is applied to the pressure field in the uniform shear flow, and the shear effect on pressure and pressure gradient (acceleration) is studied experimentally up to the Reynolds number based on Taylor micro scale is 800. The results show the excellent agreement with the prediction by theory, and the universal trend of anisotropic spectra was observed.