Surrogate-assisted optimization for anti-ship missile body configuration considering high-velocity water touching

As a crucial weapon in the sea battle,anti-ship missiles generally employ a sea-skimming penetration strategy to reduce the probability of being detected by the target radar,which greatly increases the risk of touching water caused by sensor errors or random sea conditions.To alleviate the large impact load by high-velocity water touching,a novel anti-ship missile body configuration is proposed in this paper,which is inspired by the idea of hydroplaning.A parametric geometry model is first developed to modify the configuration of the anti-ship missile body.Subsequently,a structured arbitrary Lagrange-Eulerian based Fluid-Structure Interaction(FSI)model is established to analyze the kinematics parameters of the missile body during the hydroplaning process.A missile body configuration optimization problem is then formulated to minimize the impact load considering several constraints,e.g.,horizontal velocity loss,pitch angle after touching water,and inside capacity for payload.Due to the time-consuming FSI simulation,a Kriging-assisted constrained differential evolution method is utilized to optimize the missile body configuration for reducing the impact load.During the optimization process,radial basis function and Kriging are combined with evolutionary operators to lead the search to the vicinity of the optimum rapidly.The result shows that the proposed missile body configuration can reduce the impact load by 18.8%compared with the ordinary configuration.Additionally,the optimized configuration can further yield a 17.4%impact load decrease subject to all the constraints and avoid structural damage by the high-velocity water touching,which demonstrates the effectiveness and practicability of the proposed anti-ship missile body configuration and corresponding optimization framework for reducing the impact load.

Sharp interface direct forcing immersed boundary methods： A summary of some algorithms and applications

Body-fitted mesh generation has long been the bottleneck of simulating fluid flows involving complex geometries. Immersed boundary methods are non-boundary-conforming methods that have gained great popularity in the last two decades for their simplicity and flexibility, as well as their non-compromised accuracy. This paper presents a summary of some numerical algori- thms along the line of sharp interface direct forcing approaches and their applications in some practical problems. The algorithms include basic Navier-Stokes solvers, immersed boundary setup procedures, treatments of stationary and moving immersed bounda- ries, and fluid-structure coupling schemes. Applications of these algorithms in particulate flows, flow-induced vibrations, biofluid dynamics, and free-surface hydrodynamics are demonstrated. Some concluding remarks are made, including several future research directions that can further expand the application regime of immersed boundary methods.