Investigating inflow uncertainty in LES predictions of wind loading

Large eddy simulations (LES) represent a powerful tool to quantify wind loads on buildings and assess wind hazards, but LES of the atmospheric boundary layer (ABL) can be strongly affected by uncertainties in the inflow conditions. We will present initial results of a sensitivity analysis to determine the importance of these inflow uncertainties when calculating wind pressure coefficients on a high-rise building. The results will be validated with wind tunnel measurements. We consider 3 uncertain parameters: the ABL roughness length, turbulence kinetic energy and streamwise integral time-scale. To produce incoming ABL profiles with different values for these parameters, we use a divergence-free digital filter method in combination with an optimization strategy to identify the input parameters that produce the desired ABL characteristics in the computational domain. We perform 27 LES simulations using different input parameters, and investigate their effect on the pressure distribution on the building's facade. Based on these results we will design a formal UQ approach to calculate confidence intervals for the mean, root mean square and peak pressure coefficients, and compare these results to wind tunnel measurements.