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Analytical solutions for the flexural-gravity wave resistances due to a line source steadily moving on the surface of an infinitely deep fluid are investigated within the framework of the linear potential theory. The homogenous fluid, covered by a thin elastic plate, is assumed to be incompressible and inviscid, and the motion to be irrotational. The solution in integral form for the wave resistance...
Fluid-particle interaction underpins important behavior of granular media. Particle-scale simulation may help to provide key microscopic information governing the interaction and offer better understanding of granular media as a whole. This paper presents a coupled computational fluid dynamics and discrete element method (CFD-DEM) approach for this purpose. The granular particle system is modeled...
The transformation method to control waves has received widespread attention in electromagnetism and acoustics. However, this machinery is not directly applicable to the control of elastic waves, because it has been shown that the Navier's equation does not usually retain its form under coordinate transformation. In this letter, we prove the form invariance of the Navier's equation under the conformal...
This paper gives an overview on nonlinear porous flow in low permeability porous media, reveals the microscopic mechanisms of flows, and clarifies properties of porous flow fluids. It shows that, deviating from Darcy's linear law, the porous flow characteristics obey a nonlinear law in a low-permeability porous medium, and the viscosity of the porous flow fluid and the permeability values of water...
The determination of structural dynamic stress spectrum distribution is of great significance in the structural fatigue strength evaluation as well as reliability design. In previous empirical data processing methods, the data grouping and distribution fitting were excessively coarse and contained distinctive defects. This paper proposed an effective approach to statistically group actual measured...
Granular materials exhibit abundant dissipations due to fluctuations in both granular motions and configurations (i.e., granular skeleton) evolutions. Twin granular temperatures Tk and Te are introduced accounting for two types of fluctuations, and the so-called twin granular temperatures theory is established as an extension of granular solid hydrodynamics. By using simulations, the nonaffine deformations...
It has been well recognized that, due to anisotropic packing structure of granular material, the true stress in a specimen is different from the applied stress. However, very few research efforts have been focused on quantifying the relationship between the true stress and applied stress. In this paper, we derive an explicit relationship among applied stress tensor, material-fabric tensor, and force-fabric...
This letter mainly aims to investigate the mechanical behavior within shear bands in regolith both under the Earth and the Moon conditions via the distinct element method, in which a novel contact model considering interparticle van der Waals forces and rolling resistance is employed. The results show that for regolith under both conditions the stress paths are almost identical inside and outside...
Experiments were conducted to study the generation of air core and its effect on the outflow shape and discharge in a cylindrical water tank with a bottom well-designed outlet. Depending on the stages of the air core in the tank, the outflow shape can vary from a smooth water jet to a smooth spindle shape with air-core, and to water sprays. The diameter of the nozzle size also has influence on the...
The acoustic emission (AE) features in rock fracture are simulated numerically with discrete element model (DEM). The specimen is constructed by using spherical particles bonded via the parallel bond model. As a result of the heterogeneity in rock specimen, the failure criterion of bonded particle is coupled by the shear and tensile strengths, which follow a normal probability distribution. The Kaiser...
Predicting potential changes in groundwater salinity in low-lying coastal regions due to climate change is important, where coastal vegetation is abundant, succession competition between halophytes and glycophytes plays a significant role in the salinity budget. Sea level rise enhances salinity intrusion, contributing an additional dimension to vegetation competition. A new simulation model known...
The dynamics of fluid flow through nanochannels is different from those in macroscopic systems. By using the molecular dynamics simulations, we investigate the influence of surface polarity of nanotube on the transport properties of the water fluid. The nanotube used here resembles the carbon nanotube, but carries charges of q on some atoms; overall, the nanotube is charge-neutral. Our simulation...
Kinematic dynamo problem is studied with tsunami motion in open oceans. Using long wave approximation, a series solution of the dynamo problem is established with fast convergent rate based on a small parameter relating water wave dispersive effects. Taking solitary wave and single wave as typical tsunami wave models, the magnitude of tsunami induced magnetic field is estimated at the order of 10...
Crashworthiness of cellular metals with a linear density gradient was analyzed by using cell-based finite element models and shock models. Mechanisms of energy absorption and deformation of graded cellular metals were explored by shock wave propagation analysis. Results show that a positive density gradient is a good choice for protecting the impacting object because it can meet the crashworthiness...
The Green-Naghdi (GN) theory is used here to simulate two-dimensional (2D) underwater landslide-induce tsunamis. Finite difference method is used to solve the GN equations. GN theory has different levels. There are GN-1, GN-2, ⋯, GN-K theory in GN theory. When K goes up, the GN equations will be more complicated, and the results will be more accurate. For the case simulated here, results of GN-5 theory...
The tsunami was a sudden marine disasters. Tsunami waves can quickly spread to near-shore and cause the disaster after the tsunami. So it is very important of timely monitoring and early warning of the tsunami. After several unsuccessful tsunami forecasting, the United States developed tsunami buoy specifically for the early detection of tsunami waves. Tsunami buoy can not only be able to display...
Structural optimization for crashworthiness criteria is of particular significance especially at early stage of design. The comparative study of Kriging and radial basis function network (RBFN) was performed in order to improve the crashworthiness effects of honeycomb. Improving the crashworthiness characteristic of honeycomb was achieved using LS-OPT® and domain reduction strategy. This optimization...
The finite volume method (FVM) and the lattice Boltzmann method (LBM) are coupled with each other to construct a new cross-scaling method to deal with the porous flow problem. To check the effectiveness of our developed cross-scaling LBM—FVM, the above mentioned problem is also solved by the well known LBM—LBM. Based on the data checking of the published data and the results of LBM—FVM and LBM—LBM,...
Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami waves. In this paper, we carry out the simulation of tsunami propagation based on the fully nonlinear and highly dispersive Boussinesq model, which could describe the nonlinearity and dispersion...
Basic requirement for applying isoparametric element is that the element has to be convex and no violent distortion is allowed. In this paper, a cubic quadrilateral spline element with 12 nodes has been developed using the triangular area coordinates and the B-net method, which can exactly model the cubic field for quadrilateral element with both convex and concave shapes. Neither mapping nor coordinate...
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