Analysis of drag based on local flow structures in finite domains

We develop a finite-domain force element theory to improve the calculation of body forces from local flow structures within a finite domain. By applying Gauss's theorem, the contributions of vorticity outside the integral region are transformed into boundary contributions of pressure, kinetic energy, and surface vorticity. The Bernoulli principle is combined with a virtual auxiliary potential function to eliminate dependence on pressure. This method establishes an accurate quantitative relationship between the local flow structures near a body and the forces acting on the body.