Composite propellers offer high damping characteristics and corrosion resistance when compared with metal propellers. But the design of a hybrid composite propeller with the same strength of metal propeller is the critical task. For this purpose, the present paper focusses on fluid-structure interaction analysis of hybrid composite propeller with Carbon/Epoxy, R-Glass/Epoxy and S2-Glass/Epoxy to find its strength at the same operating conditions of the baseline aluminium propeller. The surface and solid models of the hybrid composite propeller are modelled using modelling software (CATIA) and these models are imported into mesh generation software (Hypermesh) to generate the surface mesh and solid mesh respectively. This surface model of the hybrid composite propeller is imported into computational fluid dynamics software (Fluent) to estimate the pressure loads on propeller blades. These pressure loads from Fluent are imported into FEA software (Abaqus) and applied on the propeller to find the deformation and strength of hybrid composite propeller due to fluid-structure interaction loads. Optimization study is carried out on hybrid composite propeller with different layup sequences of Carbon/R-Glass/S2-Glass to find the optimum strength. From the optimization study, it is found that the hybrid composite propeller with layup-3 of 550/550/900/00/00/900/450/900/ 00/900/450/900/450/900/00/900/00 generates the least stress compared with other layups for the same pressure load obtained from fluid flow simulations. Damage initiation analysis is also carried out on hybrid composite propeller with optimized layup-3 based on Hashin damage criteria and found that the design is safe.

Viscoelastic fluid hammer is a type of fluid hammer in which a viscoelastic non-Newtonian fluid flows in a pipeline. In this study, the fluid-structure interaction in this phenomenon is investigated. The governing equations are viscoelastic fluid and structure equations which are coupled together. Viscoelastic fluid equations consist of continuity and momentum which govern the transitional flow in the pipes. Oldroyd-B model is used as the constitutive equation. This model is suitable for dilute viscoelastic solutions and Boger liquids. Structural equations include pipe axial velocity and stress equations. A two-step variant of the Lax-Friedrichs method is used to simulate fluid-structure interaction in a reservoir-pipe-valve system. A viscoelastic fluid polymer is selected and the behavior of the polymer pressure head and shear stresses during fluid hammer is investigated. Three types of couplings were examined. Junction, Poisson, and the combination of two aforementioned couplings called junction and Poisson coupling. The effects of these couplings for the fluid are modeled in three states. ideally, Newtonian and viscoelastic. The fluid viscosity in Newtonian and viscoelastic states is considered the same. The results of the study show that the imposed shear stresses with viscoelastic fluid are significantly lower than those in the Newtonian state. Comparing coupling effects during fluid hammer is found that the lowest shear stresses are assigned to Poisson coupling.

In this paper a meshless method using exponential basis functions is developed for fluid-structure interaction in liquid tanks undergoing non-linear sloshing. The formulation in the fluid part is based on the use of Navier-Stokes equations, presented in Lagrangian description as Laplacian of the pressure, for inviscid incompressible fluids. The use of exponential basis functions satisfying the Laplace equation leads to a strong form of volume preservation which has a direct effect on the accuracy of the pressure field. In a boundary node style, the bases are used to incrementally solve the fluid part in space and time. The elastic structure is discretized by the finite elements and analyzed by the Newmark method. The direct use of the pressure, as the 䐀 䐀 ential of the acceleration, helps to find the loads acting on the structure in a straight-forward manner. The interaction equations are derived and used in the analysis of a tank with elastic walls. The overall formulation may be implemented simply. To demonstrate the efficiency of the solution, the obtained results are compared with those obtained from a finite elements solution using Lagrangian description. The results show that while the wave height and the oscillations of elastic walls of the two analyses are in good agreement with each other; the use of the proposed meshless analysis not only leads to accurate hydrodynamic pressure but also reduces the computational time to one-eighth of the time needed for the finite e☮ leKmeeynwtso radnsa

Serpentine nozzle can effectively suppress the infrared radiation signatures of the aero-engine exhaust system. However, it experiences the remarkable fluid-structure interaction (FSI) process at the work condition. In this paper, the deformation behavior of the serpentine nozzle and its flow characteristic were investigated numerically. Then, the influences of the wall thickness and the geometric configuration on the FSI effect were also explored. The results show that, the mechanism of the fluid-structure interaction is formed through the data transfer of the force and the displacement at the FSI interface. Under the FSI effect, there occur the ballon-like swellings at the second S passage, and the linear section bends upward along the Y direction. They induce the special flow features including the flow separation, the shock wave and the plume vector angle. As the value of the wall thickness increases from 3mm to 6mm, the maximum of the deformation displacement of the serpentine nozzle decreases 68. 5mm. As compared to the uncoupled state, the variation of the axial thrust decreases from 2. 70% to 0. 70% at the coupled state. The circular-to-rectangular profile and the S-shaped passage enlarge the deformation behavior of the nozzle structure. The value of the axial thrust of the serpentine nozzle with 5mm wall thickness for the coupled state is lower 1. 92% than these for the uncoupled state

Large capacity cylindrical tanks are used to store a variety of liquids. Their Satisfactory performance during earthquake is crucial for modern facilities. In present paper, the behavior of cylindrical concrete tanks under harmonic excitation is studied using the finite element method. Liquid sloshing, liquid viscosity and wall flexibility are considered and additionally excitation frequency, liquid level and tank geometry is investigated. The results show a value for wall thickness to tank diameter ratio which may be used as a guide in the consideration of wall flexibility effects.

Introduction: Venous valves are a type of oneway valves which conduct blood flow toward the heart and prevent its backflow. Any malfunction of these organs may cause serious problems in the circulatory system. Numerical simulation can give us detailed information and point to point data such as velocity, wall shear stress, and von Mises stress from veins with small diameters, as obtaining such data is almost impossible using current medical devices. Having detailed information about fluid flow and valves' function can help the treatment of the related diseases. Methods: In the present work, the blood flow through a venous valve considering the flexibility of the vein wall and valve leaflets is investigated numerically. The governing equations of fluid flow and solid domain are discretized and solved by the Galerkin finite element method. Results: The obtained results showed that the blood velocity increases from inlet to the leaflets and then decreases passing behind the valve. A pair of vortices and the trapped region was observed just behind the valves. These regions have low shear stresses and are capable of sediment formation. Conclusion: The von Mises stress which is a criterion for the breakdown of solid materials was obtained. It was also observed that a maximum value occurred at the bottom of the leaflets.

fluid-structure interaction (FSI) occurs when the dynamic water hammer forces cause vibrations in the pipe wall. FSI in pipe systems due to Poisson and junction coupling has been the center of attention in recent years. It causes fluctuations in pressure heads and vibrations in the pipe wall. The governing equations of this phenomenon include a system of first order hyperbolic partial differential equations (PDEs) in terms of hydraulic and structural quantities. In the present paper, a two-step variant of the Lax-Friedrichs (LxF) method, and a method based on the Nessyahu-Tadmor (NT) are used to simulate FSI in a reservoir-pipe-valve system. The computational results are compared with those of the Method of Characteristics (MOC), Godunov's scheme and also the exact solution of linear hyperbolic fourequation system to verify the proposed numerical solution. The results reveal that the proposed LxF and NT schemes can predict discontinuity in fluid pressure with an acceptable order of accuracy. The independency of time and space steps allows for setting different spatial grid sizes with a unique time step, thus increasing the accuracy with respect to the conventional MOC. In these schemes, no Riemann problems were solved and hence field-by-field decompositions were avoided which led to reduced run times compared with Godunov scheme.

In recent decades, there has been a growing demand for composite materials with high strength to weight ratio and high stiffness to weight ratio for use in the marine industry to improve the hydrodynamic and structural performance of vessels and propulsion systems. Apart from the advantages of composite propellers over their metal counterparts, deformations of these propellers under loading can alter their hydrodynamic effects. This paper was a hydroelastic analysis of a composite marine propeller made of carbon fiber laminate. This analysis was performed by the use of CFD-FEM based on the two-way fluid-structure interaction (FSI) coupling on the 3D geometry of the KP458 propeller. The CFD results are compared with the experimental data reported by Hyundai Maritime Research Institute (HMRI), for advance ratios of 0. 1-0. 5, which shows a perfect agreement among them. An increase in the efficiency of the flexible propeller is observed in different advance ratios due to an increase in thrust (1-4%) and a decrease in torque (1-6%).