Gradual Enlargement Mesh Method in
Wave-motion of Infinite Domain
Xiangli HE1, Tongchun LI2, Hao REN2
1College
of Water Conservancy & Civil Engineering, China Agriculture Univ., Beijing,
100083, China, E-mail: hxl0806@cau.edu.cn
2College
of Water Conservancy & Hydropower Engineering,
Abstract: Generally,
the soil around the structure is semi-infinite media, and the influence of
loads to soil far from the structure is negligible under static loads. Then the
suppositional boundary could be adapted in the soil far from the structure when
the soil-structure interaction is analyzed. By simulating the soil in finite
region, the subject could be transformed to the analysis of system which is
composed of structure and finite soil. But in the analysis of dynamic
soil-structure interaction, the radiant wave from the structure would be
reflected to the finite soil by the suppositional boundary and the radiation
condition could not be satisfied, so the finite soil should not be simply
intercepted. Based on the principle of remote artificial boundary and the
method of incompatible mesh, the present article puts forward a new time domain
finite element method of gradual enlargement mesh method in which the energy
dissipation effect of remote domain can be took into account. In this method,
based on the remote artificial boundary, with the distance L (
) from artificial boundary to structure, thick mesh is
adapted in the structure, and the mesh gets wider with the distance from
computational region to structure increasing. Between thick mesh and wide mesh
the incompatible mesh is adapted, and the relationship between the
displacement, velocity, acceleration velocity of incompatible point and those
of compatible point is established by the way of linear interpolation, so the
problem of wave-motion reflection caused by the free boundary treatment of
incompatible point can be avoided. In the gradual enlargement mesh method, the
damp is applied in different partition and the high-frequency wave reflection
caused by the change of mesh can be avoided. To the characteristic of the mesh,
the corresponding wave motion input method is also put forward in this article.
The precision and reliability of the gradual enlargement mesh method are
certificated by the calculation case of typical wave origin and scatter topics.
With the gradual enlargement mesh method, the computational workload could be
decreased greatly and the worked efficiency could be increased. This method can
avoid the problem of instability and large angle incident of normal artificial
boundaries, so it can be used for checking up other artificial boundaries.
Keywords: Gradual
enlargement mesh method; Infinite Domain; wave input; foundation radiation
damping; remote artificial boundary
Fig.1 Gradual enlargement mesh model
Point A Point B
Fig. 2 Time history of
displacement in y-direction at different points
Fig. 3 Wave input model for Gradual enlargement mesh
Point A Point B
Fig. 4 Time history of
displacement in x-direction at different points