The Fluid-Structure Boundary Condition

Any airplane even flying at constant speed and horizontal motion perturbs the flow. Perturbation implies changes of pressure and velocities with respect to the unperturbed state. This is due to the fact that the fluid cannot penetrate the body’s surface and, as a consequence, the flow must change accordingly. From mathematical and modeling points of views, the problem can be formulated by imposing this physical constraint by appropriate formulation of a fluid-structure boundary condition. This is one of the key theoretical passages that lead to the final integral expressions of the Doublet Lattice Method, as will be seen later in Chaps. 26 and 27 .