Lift force of an airfoil in the form of an arc with a sink

The problem of maximizing the lift force of an airfoil in the form of an arc with a sink modeling flow removal is studied within the framework of the classical model of a steady ideal incompressible liquid flow. For a sink with a fixed flow rate, an optimal position on the upper surface of the arc is found, which ensures the greatest increase in the lift force. It is shown that, in the presence of a sink, the optimal shape of the arc with a limited curvature and chord length coincides with the optimal shape of the arc without a sink, which was designed by M. A. Lavrent'ev (an arc of a circle). The flow rate corresponding to the maximum lift force is determined, and the mechanism of the influence of flow removal on the lift force is examined.