The quasi-independent curvilinear coordinate approximation (QUICCA) method [K. Németh and M. Challacombe, J. Chem. Phys. 121, 2877, (2004)] is extended to the optimization of crystal structures. We demonstrate that QUICCA is valid under periodic boundary conditions, enabling simultaneous relaxation of the lattice and atomic coordinates, as illustrated by tight optimization of polyethylene, hexa...

This paper deals with the Saint-Venant’s torsion of thin-walled isotropic nonhomogeneous open elliptical cross section whose shear modulus depends on one curvilinear coordinates which define cross-sectional area beam. The approximate solution problem is obtained by variational method. usual simplification assumptions are used to solve uniform bars cross-sections. An example illustrates applicat...

Diffusion Tensor Magnetic Resonance Imaging (DTMRI) technique enables the measurement of diffusion parameters and therefore, informs on the structure of the biological tissue. This technique is applied with success to the static organs such as brain. However, the diffusion measurement on the dynamically deformable organs such as the in-vivo heart is a complex problem that has however a great po...

This paper reports the development and application of a finite-volume based methodology for the calculation of the flow of fluids which follow differential viscoelastic constitutive models. The novelty of the method lies on the use of the non-staggered grid arrangement, in which all dependent variables are located at the center of the control volumes, thus greatly simplifying the adoption of ge...

Biological tissues such as those involved in the eye, heart, veins or arteries are heterogeneous on one or another spatial scale and can undergo very large elastic strains. Frequently, these tissues are characterized by shell-like structures at the macroscopic scale and the physical material directions follow curvilinear paths. We consider a homogenized macro-continuum formulated in curvilinear...

Flux-vector and tlux-difference splittings for the inviscid terms of :hs compressible flc:\ equations are derived under the assumption of a general equation of state for a reai gas in squilibrium. No unnecessary assumptions. approximations, or auxiliary quantities are introduced. The formulas derived include several particular cases known for ideal gases and ;cadilq appi) to curvilinear coordin...

The equidistribution method for constructing the mo tionless regular grids is considered in the present paper. The grids are adapted to the curvilinear boundaries of the domain and to the control function, which is a priori giv en in the domain. Using the general methodology, which is based on the equdistr ibution principle, the nonlinear equations of elliptic type are obtained for the definiti...