Numerical simulations of turbulent flow in complex geometries

摘要

Numerical simulations of turbulent flow in complex geometries have been considered, in order to investigate the capabilities of different turbulence models. Two of the turbulence models under consideration are based on second-moment closure, but also two versions of the so called k - (epsilon) model have been tested. The turbulence models have been tested for various channel flows. In particular all the turbulence models have been tested in a channel where the lower wall is sinusoidal, yielding a separated flow. All of the tested models reproduce the main characteristics of the mean flow field, while the turbulent quantities are best reproduced with the second-moment closure models. It is further observed that the numerical solution is contaminated by a boundary condition dependency due to the use of wall functions. The flow field in a more complex channel is also investigated. This type of channel is used in the offshore industry for ventilation purposes. The last part of the study demonstrates how computation fluid dynamics can be used in various phases during the design of offshore ventilation systems. Both in detailed design of weather louvre profiles and in ventilation studies of offshore modules, where the walls in the module are partly covered with weather louvre. The weather louvre are modeled as a semipermeable porous medium. The numerical results are verified against wind tunnel experiments.