This paper applies the meta-modeling theory proposed by the authors to a thin curved beam. The key features which are new to the curved beam problem are the introduction of a new curvilinear coordinate system inherent to the beam configuration and the asymptotic expansion using the ratio of the beam thickness to the beam radius. The governing equations for displacement are derived from a Lagrangian of continuum mechanics, making error-free computation of the covariant derivative and systematic computation of the asymptotic expansion. Discussions are made on the derivation to clarify the significance of the two key features.
The assessment of corrosion damage is an essential part of the maintenance of steel structures. The numerical analysis of the properties of corrosion surfaces and the accurate prediction of corrosion surfaces are of great significance. In this study, four kinds of unpainted steel plates, SM400A, SM490A, SMA400AW, and SMA490AW, were used for corrosion experiments under the artificial seawater corrosive environment ISO 16539 Method B, and two atmospheric exposure environments in different regions. The corrosion depths of the steel plates were measured by a laser focus measurement system. Semi-variogram was used in the geostatistical analysis to investigate the spatial autocorrelation structure of the corrosion surfaces. By using this method and the ordinary kriging technique, a method was proposed to simulate the spatial characteristics of the corrosion surfaces. The simulation results indicated that the corrosion depth and surface morphology of the corrosion surface were in high agreement with the experimental results. In addition, a deep learning model based on generative adversarial network (GAN) was used to build a prediction model of the corrosion surface. The spatial properties of the prediction model were verified using the geostatistical analysis method proposed in this study, and the results showed that the predictions had the same spatial properties as the actual corrosion surface.
A computation method was proposed for the interactions between Newtonian fluids and deformable solid objects which swell by absorbing the surrounding flids. The direct-forcing immersed boundary method and mass-spring model are used to estimate the fluid-solid interactive forces and deformations of the solid. The swelling of the object is simulated by changing the natural lengths of the spring models. In addition, the solid-solid interaction is treated by utilizing the distinct element method. The proposed method was applied to three numerical experiments. As a result, it was shown that the basic behaviors of the swelling-deformable objects are reasonably calculated with the present method.
This study is an extension based on our previous work 1,2), in which we mainly discussed the µ(I) rheological model for quasi-monodisperse circular and elliptic systems. In this paper, we numerically study the inclined plane flows composed of two-sized circular particles through the 2D discrete element method. By carrying out simulations with different size ratios Sr , bulk volume ratios Vr , and slope angles θ (altogether 125 different systems), we discuss how this rheological model works for bi-disperse systems in detail. It is found that (1) the µ(I)-rheology model is still valid for the bi-disperse flows of different size ratios Sr and volume ratios Vr; (2) the contact type (large to large, small to small, and large to small particles) proportions are not dependent on the shear rates, which enables us to formulate them for the definition of a generalized inertial number Î; (3) the dependence of fitting parameters, including the mean effective friction coefficients µ0 and solid fraction φ0 in the quasistatic regime, on the system bi-dispersity (i.e., Sr and Vr) is discussed and clarified.
In the recent flood disaster, the remarkable water level rise in river flows over a short period led to the levee breaching, which caused severe damage in the landside region. Therefore, numerical methods that can predict flood flows and bed deformation around a levee are of great significance for flood mitigation. In this study, a three-dimensional (3D) numerical model of open channel flows in a boundary fitted coordinate system with the density function method is used, and by comparing the hydraulic characteristics of simulation, such as water level and velocity distributions, to the previous experiments of lateral overtopping flows around a side weir in the curved channel, the reliability of the numerical model is validated and three-dimensional flow structures around side weir have also been investigated.