The application of computational fluid dynamics with large eddy simulation formulation
in wind engineering is an area of continuous research and development. Driven by the re-
quirement for a better understanding of atmospheric boundary layer flows, advancements in
high-performance computing, and emerging of robust open-source CFD codes, a set of nu-
merical developments are proposed. This thesis investigates the application of inflow/outflow
boundary conditions to a FEM-based Large Eddy Simulation (LES) code in a numerical wind
tunnel setup. With regards to the outflow treatment, two formulations are implemented,
namely, the convective outlet condition and the sponge zone approach. Both methods are
validated through prototypical external wind flow problems, namely flow around a square
cylinder and the 3D CAARC building benchmark. The results indicate that the proposed
developments reduce backflow effects caused by the hard enforcement of static pressure at
the outlet. Thus, maintaining solution convergence with the potential of reducing the size of
the computational domain downstream. With regards to the inflow conditions, a synthetic
turbulence generator is implemented following Mann stochastic wind model for atmospheric
turbulence. To ensure the incompressibility of the synthetic velocity field, a divergence-free
correction is applied. In addition, a body force approach following linear momentum theory
is proposed to prescribe the turbulent fluctuations on a plane in the interior of the domain.
The inflow conditions are tested by running a standard 3D channel flow problem and the
3D CAARC building case. The results show a close agreement with the reported theory in
terms of statistics and energy spectra. In addition, the pressure fluctuations caused by the
violation of the continuity constraint are significantly reduced. The spectral analysis for the
forces on the building revealed the importance of turbulent inflow conditions for evaluating
dynamic wind effects on the structure. It was also concluded that the body force approach
is a promising alternative to the conventional inlet condition for prescribing turbulent fluc-
tuations with a similar quality of results. Finally, outlook developments for outflow and
inflow boundary conditions are proposed. For the outflow conditions, a hybrid boundary
condition combining the convective outlet and sponge layer approach is suggested. For the
inflow conditions, improvements to the current synthetic wind condition are proposed with
the potential of reducing computational effort and direct application to structural analysis.
«
The application of computational fluid dynamics with large eddy simulation formulation
in wind engineering is an area of continuous research and development. Driven by the re-
quirement for a better understanding of atmospheric boundary layer flows, advancements in
high-performance computing, and emerging of robust open-source CFD codes, a set of nu-
merical developments are proposed. This thesis investigates the application of inflow/outflow
boundary conditions to a FEM-based Large Eddy Si...
»