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In this paper, symmetric water entry of twin wedges is investigated for deadrise angle of 30 degree. Three numerical simulation of a symmetric impact, considering rigid body dynamic equations of motion in two-phase flow is presented. The two-phase flow around the wedges is solved by Finite Element based on Finite Volume method (FEM-FVM) which is used in conjunction with Volume of Fluid (VOF) scheme in ANSYS Fluent and ANSYS CFX and Phase Field scheme in COMSOL Multiphysics. The method and scheme of simulation are validated by experimental data for geometry with one wedge. The dynamic mesh, mesh motion and moving mesh models are used to simulate dynamic motion of the wedges in ANSYS Fluent, ANSYS CFX and COMSOL Multiphysics, respectively. The vertical velocity and pressure coefficient versus time are determined and comparisons of the computed mentioned parameters against experimental data are performed. The eight characteristics effects of fluid flow are investigated till 0.25 second after wedges falling including impact event. It is demonstrated that the ANSYS Fluent and k-ε were the best software and viscous model, respectively.

The present paper focuses on the assessment of turbulent effects on the impact force, spray, and secondary impact force of the wedge water entry. For this purpose, a finite element based finite volume method code coupled with volume of fluid has been developed. The k-e method has also been implemented to model the turbulence effects. The developed code is validated against experimental data with good accordance and is then used to model the water entry of wedges with deadrise angles ranging from 10 to 60 degrees at different velocities of 1 and 2 m/s with laminar and turbulent assumptions. Subsequently, the resulting forces and free surfaces are compared for three critical instances of “Peak”, “Hollow”, and “2nd impact”. It is illustrated that turbulence has negligible effects on the force and free surface in the main water entry process. However, turbulent effects rise up to 14.23% for the secondary impact forces.

The growing application of catamaran planing hulls implies the significance of comprehensive studies on different aspects of these types of vessels. In this context, slamming is an important phenomenon which is generally simplified to the wedge water entry of the planing hulls. In the present paper, the constant speed water entry of twin wedges, as a simplification of a planing catamaran hull, is numerically modeled at three deadrise angles and five demi-hull separations. Control volume-based finite element has been used to solve two-dimensional Navier–Stokes equations coupled with volume of fluid method for two-phase flow modeling. The results of numerical method have been validated against experimental data. It has been illustrated that low demi-hull separation causes an increase in the impact forces by up to 19%, an effect which decreases rapidly with an increase in demi-hull separation. The obtained results also indicate that secondary impact forces between and outside the hulls are asynchronous due to the reciprocal effects of demi-hulls. Moreover, spray characteristics have been defined and it has been demonstrated that the height of spray between hulls decreases by a decrease in the demi-hull separation.

This paper presents numerical solution of one-dimensional enhanced Boussinesq equations introduced by Madsen and Sorensen for modeling the solitary wave propagation in three different physical situations. Governing equations are spatially discretized using weighted residual Galerkin approach. To implement the linear finite element method, an auxiliary equation is introduced in order to simplify the discretization task of the third-order spatial derivatives present in momentum equation. Exact solitary wave solutions are used to specify the initial data for the incident solitary waves in the numerical model and for verification of the corresponding computed solutions. The proposed model has been used to simulate important wave phenomena including solitary wave propagation, shoaling, absorption and reflection. Validity of the developed code has been assessed by comparing the results against published analytical solutions and experimental measurements. In order to compare the current results against the numer...

In this study, the unsteady flow of three dimensional rectangular ducts is investigated using the energy gradient method. The instability maximum ratio of the energy gradient in the two orthogonal directions is predicted for different aspect ratios. For specific Reynolds numbers, the ratio of the energy gradient in the two orthogonal directions is obtained for different aspect ratios and validated with the previous available data. The comparison of the present results shows excellent agreement with the previous available data. From the results of present work we conclude that as the aspect ratio increases the time required for the flow to reach the steady state is lesser, in other words the larger the aspect ratios are the sooner the steady state flow conditions are achieved. Resultsof this paper show that the maximum ratio of the energy gradient in the two orthogonal directions, Kmax, for three dimensional rectangular duct flows is in the range of 402-403.Also, the variations of K/Re versus y/b at different dimensionless times and different aspect ratios are investigated. The onset of the instability in R=∞ is so similar to the plane poiseulle’sresult of Dou(2006).