Computation of turbulent free‐surface flows around modern ships

Abstract

SUMMARYThis paper presents the calculated results for three classes of typical modern ships in modelling of shipgenerated waves. Simulations of turbulent free-surface ows around ships are performed in a numerical water tank, based on the FINFLO-RANS SHIP solver developed at Helsinki University of Technology. The Reynolds-averaged Navier-Stokes (RANS) equations with the artiÿcial compressibility and the nonlinear free-surface boundary conditions are discretized by means of a cell-centred ÿnite-volume scheme. The convergence performance is improved with the multigrid method. A free surface is tracked using a moving mesh technology, in which the non-linear free-surface boundary conditions are given on the actual location of the free surface. Test cases recommended are a container ship, a US Navy combatant and a tanker. The calculated results are compared with the experimental data available in the literature in terms of the wave proÿles, wave pattern, and turbulent ow ÿelds for two turbulence models, Chien's low Reynolds number k-model and Baldwin-Lomax's model. Furthermore, the convergence performance, the grid reÿnement study and the e ect of turbulence models on the waves have been investigated. Additionally, comparison of two types of the dynamic free-surface boundary conditions is made.

Applications of the artificial compressibility method for turbulent open channel flows

“…Many authors [7][8][9] have applied this method successfully. In addition, the ACM has been applied to free surface ows by a number of authors [10,11]. In this paper, we decompose the pressure into its hydrostatic and hydrodynamic parts, and the ACM is applied only to the hydrodynamic pressure.…”

Estudo do Galgamento de Estruturas Marítimas utilizando um Modelo Numérico baseado na Teoria da Onda em Condições de Água pouco Profunda

“…Note that in this report we shall present our results for a smooth impermeable sea dike. Another case (over a vertical fixed barrier in the front of a pier) can be found in our current study [19,71]. The calculated results are represented in terms of the wave-induced velocity fields and the time history of the surface elevation η (m) at certain points.…”

“…surface boundary condition (IFSBC)), the Reynolds stress free surface boundary condition (RSFSBC) [71] is given by p = ρ (ν + ν t ) 2 ∂w ∂z − ∂h ∂x ∂u ∂z + ∂w ∂x − ∂h ∂y ∂v ∂z + ∂w ∂y (41) indicating that the effects of the subgrid-scale (SGS) models on the free surface can be captured via eddy viscosity ν t specified by Eq. (40).…”

Resistance of large caisson in floating transport considering the influence of air

“…In the previous research, effect of air resistance on caisson is seldom taken into account in numerical simulation, let alone the air resistance on the inner wall of caisson, which actually has a great influence on the caisson. With the development of computational fluid dynamics (CFD) technology, the volume of fluid (VOF) method on three-dimensional viscous flow is widely applied in the aspect of ship resistance behavior, which can accurately compute the air resistance of caisson and solve the detailed flow field around the caisson, especially around the head and tail of caisson [3][4][5][6][7]. The structure of caisson is similar to that of trimaran ship, so the numerical simulation of caisson's resistance behavior refers to the simulation of ship resistance.…”