Abslrczc-The 3-dimensional finite-difference time-domain method in non-orthogonal co-ordinates (non-standard FDTD) is used to calculate the frequencies of resonators. The numerical boundary conditions of the method are presented. The influences of boundary conditions and discrete meshes on the numerical accuracy are investigated. We present the nonstandard FDTD method using the boundary-orthogo...

This paper presents an efficient and novel geometric flow-drivenmethod for mesh optimization of multicomponent tetrahedral meshes with non-manifold boundaries. The presented method is composed of geometric optimization and topological transformation techniques, so that both location and topology of mesh vertices are optimized. Due to the complexity of non-manifold boundaries, we categorize the ...

This paper describes an automatic and efficient approach to construct unstructured tetrahedral and hexahedral meshes for a composite domain made up of heterogeneous materials. The boundaries of these material regions form non-manifold surfaces. In earlier papers, we developed an octree-based isocontouring method to construct unstructured 3D meshes for a single-material (homogeneous) domain with...

New non-reflecting boundary conditions are introduced for the solution of the Helmholtz equation in a waveguide. These boundary conditions are perfectly transparent for all propagating modes. They do not require the determination of these propagating modes but only their propagation constants. A quasi-local form of these boundary conditions is well suited as terminating boundary condition beyon...

When simulating fluids, tetrahedral methods provide flexibility and ease of adaptivity that Cartesian grids find difficult to match. However, this approach has so far been limited by two conflicting requirements. First, accurate simulation requires quality Delaunay meshes and the use of circumcentric pressures. Second, meshes must align with potentially complex moving surfaces and boundaries, n...

The last decade has witnessed a resurgence of interest in Cartesian mesh methods for CFD. In contrast to body-fitted structured or unstructured methods, Cartesian grids are inherently non-body-fitted; i.e. the volume mesh structure is independent of the surface discretization and topology. This characteristic promotes extensive automation, dramatically eases the burden of surface preparation, a...

This communication presents a progress report on an ongoing project aiming at the computation of complex fluid flows with a realistic constitutive law, which would takes into account the pseudoplastic, viscoelastic and thixotropic behaviour of the materials. The flow solver is based on the LS-STAG method, which is an immersed boundary (IB) method that allows the computation of flows in complex ...

This paper describes an automatic and robust approach to convert 3D CAD assembly models into unstructured hexahedral meshes that are conformal to the given B-Reps (boundary-representations) with sharp feature preservation. In previous works, we developed an octree-based isocontouring method to construct unstructured hexahedral meshes for manifold and non-manifold domains. However, sharp feature...

We propose a method for generating well-shaped curved unstructured meshes using a nonlinear elasticity analogy. The geometry of the domain to be meshed is represented as an elastic solid. The undeformed geometry is the initial mesh of linear triangular or tetrahedral elements. The external loading results from prescribing a boundary displacement to be that of the curved geometry, and the final ...