Added mass

About: Added mass is a research topic. Over the lifetime, 2849 publications have been published within this topic receiving 47899 citations.

Computation of added mass and damping coefficients due to a heaving cylinder

Abstract: We present the boundary value problem (BVP) for the heave motion due to a vertical circular cylinder in water of finite depth. The BVP is presented in terms of velocity potential function. The velocity potential is obtained by considering two regions, namely, interior region and exterior region. The solutions for these two regions are obtained by the method of separation of variables. The analytical expressions for the hydrodynamic coefficients are derived. Computational results are presented for various depth to radius and draft to radius ratios.

Experimental Study of a Vibrating Disk Submerged in a Fluid-Filled Tank and Confined With a Nonrigid Cover

Abstract: Determining the dynamic response of submerged and confined disklike structures is of interest in engineering applications, such as in hydraulic turbine runners. This dynamic response is heavily affected by the added mass and damping as well as the proximity of solid boundaries. These solid boundaries are normally considered as completely rigid in theoretical or numerical calculations, however, this assumption is not always valid. Some hydraulic turbines have noncompletely stiff casings, which can modify the dynamic response of the runner itself, affecting specially its natural frequencies and damping behavior. To determine the influence of noncompletely rigid nearby surfaces in the dynamic behavior of a submerged structure, an experimental test rig has been constructed. This test rig is based on a disk attached to a shaft and confined in a tank covered with two different casings with different mass and stiffness. For both covers and different disk to cover distances, natural frequencies and damping ratios of the disk have been obtained experimentally. Accelerometers installed on the disk and covers as well as pressure sensors are used for this purpose. Results obtained for all the cases are discussed in detail and compared with a simplified theoretical model.

An analysis of particle saltation dynamics

Abstract: A two-dimensional particle saltation model for unidirectional flow is applied to simulate the motion of single particles. The equations of motion include added mass, gravity, drag, shear lift, Basset history, and Magnus or spin lift forces. A sensitivity analysis is performed on the forces, initial lift-off speeds and angles, and for different size particles. The Magnus lift force is found to have a significant effect on a particle's trajectory for coarse sand sized and larger particles. The shear lift and Basset history forces cause particles to saltate farther. Most of the forces vary with particle size. The model predictions compare favorably to observations if appropriate initial conditions are assumed.