An unsteady vortex-lattice method has been augmented to model the effect of the LEV, which is modeled as a vortex sheet. A low-order method is presented for modeling the formation of the LEV on finite wings. Although considerable progress has been made in the low-order modeling of LEV formation over airfoils, the prediction of LEV formation on finite wings remains a challenge. This can then be used as an indicator of the usefulness of the force distribution results.Ī characteristic feature of flows past many oscillating airfoils and wings is the leading-edge vortex (LEV). It can, however, predict the shedding of LEVs to a limited extent via the leading-edge suction parameter criterion. Although the inviscid spanwise force distributions are accurate for small-amplitude kinematics, the ULLT cannot model three-dimensional vortical structures, and thus it cannot correctly predict the force distribution due to the LEV. Three-dimensional effects stabilize leading-edge vortex (LEV) structures, resulting in a good prediction of whole wing force coefficients by ULLT. This paper establishes that ULLT still provides a useful solution for low-Reynolds-number, large-amplitude kinematics problems, by comparing ULLT results against those of experimentally validated computational fluid dynamics simulations at Re=10,000. Although these assumptions might be suitable for small-amplitude aeroelastic problems at high Reynolds numbers, modern engineering applications increasingly involve lower Reynolds numbers, large-amplitude kinematics, and vortex structures that lead to aerodynamic nonlinearities. Most formulations of the method assume inviscid flow and small amplitudes. Unsteady lifting-line theory (ULLT) is a low-order method capable of modeling interacting unsteady and finite wing effects at low computational cost.

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