Sukhorukov A. L., Titov M. A., Chernyshev I. A.
This paper presents the consideration of methodological aspects of determination of coefficients of rotary derivatives of hydrodynamic forces and moments of underwater objects. The article shows that mechanism of «sliding computation meshes» implemented in many computing software packages of mechanics of fluids allows setting oscillations of the object in the flow by trim angle and determining hydrodynamic impacts on the object based upon numeric solution of Reynolds-averaged Navier—Stokes equation. The paper contains the main stages of the development of the calculation model for solving similar tasks. The calculation model has been verified using as an example the flow around a wide airfoil profile producing rotary oscillations in the stream. The calculated and experimental data have been compared. Phase difference between the low of airfoil motion and corresponding hydrodynamic impacts has been identified. The non-stationary calculation of the flow of viscous fluid past the underwater object resulted in determination of velocity and pressure fields in the stream. Ratios have been obtained which allows determination of coefficients of rotary derivatives of hydrodynamic forces and moments based on the preset values of hydrodynamic impacts. The presented approach allows the validity of the stationary state hypothesis to be estimated when studying underwater object motion.
