RETRACTED ARTICLE: Evaluation of the Filtered Noise Turbulent Inflow Generation Method

Abstract

Flows around buildings and in urban areas have the ability to exchange mass and momentum through mixing layers. The complex dynamical phenomena arising in mixing layers can be studied using Large Eddy Simulation (LES). As mixing layers depend on the turbulence conditions upstream of the buildings or urban areas, appropriate turbulent inlet conditions have to be provided to a simulation. Due to the high efficiency and level of control, the filtered noise inflow method was selected. The control over the Reynolds stresses as well as nine length scales make this method suitable to replicate conditions measured in experiments. In this paper, a formal method to obtain the filter coefficients is presented. This is achieved by relating the spatial filtering to a Finite Impulse Response (FIR) filter and the temporal filtering to an Autoregressive (AR) model. Three closed-form solutions for the spatial filter coefficients are presented having a Gaussian, doubleexponential and exponential correlation function. By means of an LES simulation of a turbulent wall-bounded flow, the input-output behaviour is investigated. It was found that a combination of a Gaussian filter with length scales that increase with increasing wall distance result in the fastest downstream development of the artificial turbulence and the smallest loss of turbulent kinetic energy. Keywords Inflow Generator • LESWe want to thank for the essential contribution by Marc Immer, who obtained the doctoral degree at ETH Zurich (DISS. ETH NO. 23208). We also thank ETH Zurich for their support by means of the Hartmann Müller-Fonds on grant ETH-32 11-2.