Urban Wake-Field Generation Using Large-Eddy Simulation for Application to Quadrotor Flight

Abstract

A method is presented for using large-eddy simulation to generate urban wake fields for use in studying the effects on the autonomous flight performance of a small quadrotor. The flowfield is solved around a single square building using OpenFOAM and stored in a database accessed by a MATLAB/Simulink flight simulator. Four flight missions are evaluated to compare the difference in performance between wake fields generated by Reynolds-averaged Navier–Stokes and large-eddy simulation solutions. The results of the holding position in a constant freestream wind show both methods produce similar results and can hold position in all three directions within approximately body lengths. When the quadrotor is in or on the boundary of the building wake, the maximum deviation volumes, as calculated when using a Reynolds-averaged Navier–Stokes or large-eddy simulation air wake, can differ by two orders of magnitude. Additionally, the large-eddy simulation air wakes can cause skewed deviations by as much as five to one in a given direction for both holding position and moving along a desired flight path. Since the turbulent large-eddy simulation wake field more accurately reflects the flow physics present within the wake of real-world structures, it is recommended that large-eddy-simulation-generated wake fields be used when designing and testing autonomous control algorithms for multirotor unmanned aerial vehicles on the order of 0.5 m in size and 2 kg in mass.