Development of a parallel code to simulate skewed flow over a bluff body

This paper outlines a new complex geometry large-eddy simulation code using finite differences and a multigrid Poisson solver written for a parallel computer. The flow domain may be constructed from an arbitrary arrangement of rectangular blocks thus permitting flow in regions with complicated shapes, and may be mapped to any number of processors up to the number of blocks. The code is used to simulate turbulent flow at a Reynolds number of 3000 past a cube placed at ground level in rough terrain with its sides set 45° to mean flow direction. Preliminary results are presented which reproduce the conical vortices on the top of the cube

Turbulent simulation of open channel flow at low Reynolds number

A numerical technique for simulating turbulent flows in which the free surface is allowed to undergo arbitrarily large deformations and is subject only to a maximum slope limit is applied to turbulent open channel flow at Reynolds number of approximately 3000 based on the surface velocity and depth.The test problem has been extensively studied in the literature and allows detailed comparisons to be made.It is found that the method is in general agreement with published results and can be used for a more extensive examination of turbulent fluid mechanics at a free surface

Large eddy simulation of vortex shedding from cubic obstacle

This paper discusses the large eddy simulation technique as applied to vortex shedding from a cubic obstacle placed in a turbulent wind environment and presents results from a recent large-scale computation of this flow. The simulation was sufficiently resolved to capture the dynamics of the conical vortices on the roof of the obstacle and to predict the roof pressure footprint in good agreement with the experimental findings. The3D visualizations of the vortex shedding and an analysis of the mean flow topology are also presented. The computations used a grid of ~107 nodes, and they were performed on a Cray T3E parallel machine. The turbulent inflow was taken from a separate precursor simulation targeted so that the obstacle represents a building placed in an urban wind environmen

Turbulent simulation of open-channel flow at low Reynolds number

A numerical technique for simulating turbulent flows in which the free surface is allowed to undergo arbitrarily large deformations and is subject only to a maximum slope limit is applied to turbulent open channel flow at a Reynolds number of approximately 3000 based on the surface velocity and depth. The test problem has been extensively studied in the literature and allows detailed comparisons to be made. It is found that the method is in general agreement with published results and can be used for a more extensive examination of turbulent fluid mechanics at a free surfac

Simulation of skewed turbulent flow past a surface mounted cube

The flow past a cubic ground-mounted obstacle placed in a turbulent wind environment is studied using the large eddy simulation technique. The wind environment is taken from a pre-computed database containing the time-dependent inflow boundary conditions and representing a typical full-scale urban wind environment (Jenson number J=60). The Reynolds number R=10 000 is high enough for viscous scaling effects to be ignored, the turbulence intensity is about 15% at the cube height, and the integral length Lux is about 1.1 times the cube height h. The cube is aligned with one corner pointing upstream so that a pair of conical roof vortices are created. The computational grid used is effectively 362×226×98 in the streamwise, spanwise, and vertical directions, i.e. about 3×107 degrees of freedom, and uses 32 grid points along the sides of the cube. Two simulations are performed: (a) the flow with the cube absent so that the reference wind environment can be assessed; and (b) the flow past the cube for that wind environment. We present the flow topology as given by the mean streamlines, the roof pressures, the mean and fluctuating velocity and pressure field, and flow visualisation of the unsteady vortex shedding. A new shedding mechanism is identified which explains the turbulence statistics found in the wake.<br/

Large-eddy simulation of turbulent flow in an asymmetric compound open-channel

A Large Eddy Simulation of turbulent flow in a compound open channel with one floodplain is reported for a Reynolds number of approximately 42000. The results are in good agreement with experimental measurements and previous numerical calculations. The mean velocity field, secondary circulation field, bed stress distribution, and lateral stress distribution are presented in detail