Development of a multi-block high-order DNS code for turbulent flow simulations

Abstract

A high-order finite-differences direct numerical simulation code is developed for studying turbulent flows over complex geometries. The solver uses a global mapping based multi-block arrangement, with each block consisting of a structured mesh and the adjacent blocks overlapping each other along the interfaces. The physical bounds of interfaces are determined by using a pre-processing, and a pre-compiler is developed to reduce the computational costs by simplifying the expensive Jacobian calculations. The code is validated for several benchmark tests including free-stream preservation on a single-block wavy grid. For multi-block application, simulation of a square jet in a turbulent cross flow has been performed. The flow conditions are Reynolds number Re∞ = 1000, based on the free-stream quantities and the jet exit width, and a jet to a cross flow velocity ratio of R = 0.5, 1.5, respectively. A counter-rotating vortex pair has been captured downstream of the jet exit and it was also found that the streamwise and the spanwise mean velocity profiles are in reasonable good agreements with available experimental measurements. However, some discrepancies are observed in other flow statistics such as the normal mean velocity and the kinetic energy distributions, and they are probably due to the low Reynolds number effect of the simulation.