Effects of distributed pressure gradients on the pressure–strain correlations in a supersonic nozzle and diffuser

Abstract

Direct numerical simulation (DNS), based on high-order numerical schemes, is used to study the effects of distributed pressure gradients on the redistribution of fluctuating kinetic energy in supersonic nozzle and diffuser flow with incoming fully developed turbulent pipe flow. Axisymmetric geometries and flow parameters have been selected such that shock waves are avoided and streamline curvature remains unimportant. Although mean extra rates of strain are quite small, strong changes in Reynolds stresses and their production/redistribution mechanisms are observed, in agreement with findings of Bradshaw (J. Fluid Mech., vol. 63, 1974, pp. 449-464). The central role of pressure-strain correlations in changing the Reynolds stress anisotropy is highlighted. A Green's function-based analysis of pressure-strain correlations is presented, showing remarkable agreement with DNS data.

Invariants of the velocity gradient tensor in a spatially developing compressible round jet

“…Time integration is carried out using a low-storage third-order Runge-Kutta scheme (Williamson 1980). This formulation has been extensively used for DNS of supersonic pipe flow in cylindrical coordinates (Ghosh et al 2010) and supersonic nozzle and diffuser flows in generalized curvilinear coordinates (Ghosh & Friedrich 2014).…”