某高陡山坡排土场动力-流固耦合稳定性分析

基于拟静力法,数值模拟分析了高陡山坡排土场在降雨饱和地震力组合最不利工况下的稳定性情况。基于拟静力法下的动力-流固耦合稳定性分析,能较好地模拟排土场在2种作用组合下的稳定情况,得到的安全系数能较好吻合,为复杂排土场的稳定性分析提供了有效的方法。

Application of the generalized quasi-complementary energy principle to the fluid-solid coupling problem

The fluid-solid coupling theory, an interdisciplinary science between hydrodynamics and solid mechanics, is an important tool for response analysis and direct design of structures in naval architecture and ocean engineering. By applying the corresponding relations between generalized forces and generalized displacements, convolutions were performed between the basic equations of elasto-dynamics in the primary space and corresponding virtual quantities. The results were integrated and then added algebraically. In light of the fact that body forces and surface forces are both follower forces, the generalized quasi-complementary energy principle with two kinds of variables for an initial value problem is established in non-conservative systems. Using the generalized quasi-complementary energy principle to deal with the fluid-solid coupling problem and to analyze the dynamic response of structures, a method for using two kinds of variables simultaneously for calculation of force and displacement was derived.

Influence of Forward Speed on the Lateral Vibration of a Slender Structure in Water

In this paper,the effects of forward speed on the lateral vibration of a slender structure in an infinite fluid are considered.By equating the bending stress of the structure with the hydrodynamic force acting on it,the equation which governs the fluid-structure interaction of a slender structure both vibrating and moving in water is obtained.Numerical results show that the influence of forward speed on the vibration of a slender structure in water is significant.It behaves like damping,reducing both natural frequencies and responses significantly.

Design of Ocean Floating Structures:Prediction of Hydrodynamic Coefficients

[Introduction] Accurate calculation of the hydrodynamic coefficients for floating structures and the investigation of the flow field distribution around floating bodies on the marine free surface are essential for improving the engineering design and application of marine structures.[Method] This study utilized the computational fluid dynamics(CFD) approach and the Reynolds Averaged NavierStokes(RANS) method and considered the effects of viscosity and free surface interactions on the hydrodynamic behavior of floating structures.By employing the dynamic mesh technique,this study simulated the periodic movements of simplified three-dimensional(3D)shapes:spheres,cylinders,and cubes,which were representative of complex marine structures.The volume of fluid(VOF) method was leveraged to accurately track the nonlinear behavior of the free surface.In this analysis,the added mass and damping coefficients for the fundamental modes of motion(surge,heave,and roll) were calculated across a spectrum of frequencies,facilitating the fast determination of hydrodynamic forces and moments exerted on floating structures.[Result] The results of this study are not only consistent with the results of the 3D potential flow theory but also further reflect the role of viscosity.This method can be used for precise calculation of the hydrodynamic coefficients of floating structures and for describing the flow field of such structures in motion on a free surface.[Conclusion] The methodology presented goes beyond the traditional potential flow approach.

Aerodynamic performance of the flexibility of corrugated dragonfly wings in flapping flight

At low Reynolds numbers,the variable flexibility of flapping insect wings is considered essential in improving the favorable aerodynamic forces.To further explore whether significant aerodynamic coupling exists between the microstructure and passive flexible deformation,this paper proposes three technical comparison airfoils:a corrugated wing with deformation,a symmetric flat plate wing with deformation,and a corrugated wing without deformation.Based on STAR-CCM+software,this paper numerically solves the Navier-Stokes equations using the fluid-structure interaction method.The results show that the aerodynamic performance of the flexible corrugated wing is better than that of the rigid corrugated wing,and its lift and thrust are both improved to a certain extent,and the thrust efficiency of the flexible corrugated wing is significantly higher than that of the flexible flat plate.Although the thrust is improved,a part of the lift is lost,and as the flapping amplitude increases past 35°,the disparity gradually increases.A comparison of the flexible technical airfoils shows that the corrugated structure promotes thrust and retards lift,which is closely related to the formation and dissipation of strong vortex rings during the downstroke phase.On the premise of maintaining typical flapping without falling,dragonflies can fly with skillful efficiency by adjusting the way they flap their wings.The results of this work provide new insight into the formation and role of thrust in flapping maneuvering flight and provide a specific reference for developing new bionic flapping-wing aircraft.