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The market for planing boats has shown steady growth in the recent years and this has caused an increase in the need for designing tools. The need is even more vital for the prediction of seakeeping and maneuverability of planing boats. Although the numerical methods are proved to be useful for the displacement vessels, they seem to be relatively impractical dealing with the complexities of the hydrodynamic behavior of planing boats. In this paper, a simple method for prediction of Heave, Pitch and Roll motions of the planing vessels in regular waves is presented. In the formulation of the present mathematical model, a 2-dimensional technique using momentum theory is applied. Different aspects of the added mass and 2D+t theories are also implemented for the section-based simulations of the planing vessel. The developed method is analyzed through a set of validation tests while the experimental results of the literature are used in order to validate the obtained results. The results are then evaluated in different degrees of freedom and favorable agreement has been achieved against the experimental data.

In this paper, viscous fluid flow over an unconventional diamond-shaped obstacle in a confined channel is simulated in low to moderate Reynolds numbers. The diamond-shaped obstacle is altered geometrically in order to represent different blockage coefficients based on the channel height and different aspect ratios based on the length to height ratios of the obstacle. An in-house finite difference Navier-Stokes solver using staggered grid arrangement and Chorin's projection method is developed for the simulation of the laminar viscous flow. The numerical solver is validated against numerical results that are presented in the literature for the flow over rectangular cylinders and good agreement is observed. Grid resolution has been studied within a mesh convergence test and as a result, suitable grid dimension is achieved. A series of simulations have been carried out for each set of geometry and configuration in order to find the critical Reynolds number for each case in which the vortex shedding will occur. Therefore, simulations are divided into two groups of steady and unsteady flows. In the case of unsteady flow, nondimensional Strouhal Number (St) is investigated and results prove the dependency of St on the blockage coefficient and aspect ratio. It is shown that the Strouhal number will increase with the rise of blockage ratio and the local maximum of St will occur at lower Re for geometries with lower aspect ratios (bluff bodies) than geometries with higher aspect ratios, i.e. with more streamlined bodies.

A harmonic balance method is used to study the unsteady flows at low-speed regimes typically seen for wind turbines. The frequency-domain technique is applied to the Reynoldsaveraged Navier-Stokes governing system of equations with the Spalart-Allmaras turbulence model. The convergence, stability and accuracy of the compressible solver is improved via a fully coupled viscous preconditioning designed for low speed flows that fall in the essentially incompressible flow regime. The viscous preconditioner couples the NavierStokes equations to the turbulence model through the correct implementation of the preconditioning matrix and the subsequently matrix-valued artificial dissipation term. Finally, the viscous low-speed preconditioning is enhanced with a mixed-mechanism that would increase the stability and improve the convergence of the harmonic balance solver used for the simulation of unsteady periodic flows.

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In this paper, the most prevalent methods of reducing noise from the marine propellers are surveyed and introduced. Subsequently, these methods are analyzed and classified as five different categories. This categorization is conducted from the stand points of technology and cost, the type of noise (cavitation, non-cavitation noise), the method of noise reduction (change in propeller geometry, modification of inlet flow, and confinement of the propeller), frequency of the targeted noise, and simplicity of implementation of the method of noise reduction in the existing vessels. The scientific classification performed in this article would bring about better recognition of and acquaintance with each of the mentioned methods of noise reduction, its limitations in cost and applications, which would in turn help the designers and the decision makers make the right decision under different operational circumstances.

A mathematical model is utilized in order to calculate three-dimensional pressure distributions on planing hulls. This type of modeling is able to determine the hydrodynamic and hydrostatic pressures acting on the bottom of these hulls. As a result, the total 3-dimensional pressure exerted on the planing hull as a sum of hydrostatic and hydrodynamic pressures can be evaluated. Empirical equations introduced in previous works have been used as the fundamentals for the present mathematical modeling method. The obtained results are compared against available experimental results and results of empirical equations in order to validate the proposed method. The outcome of the R-squared tests conducted on these comparisons shows favorable accuracy of the results. After evaluation of hydrodynamic pressure, the effects of trim and deadrise angles and wetted length on the 3-dimensional pressure distribution are analyzed. Finally, the total pressure on planing hull and the effect of velocity coefficients are studied.