arXiv subjects
Publications and source records attributed to Carlos Valero Valdes.
The purpose of this paper is to provide a formula for the effective diffusion operator obtained by projecting the 3-dimensional diffusion equation onto a 2-dimensional plane, assuming reflective boundary conditions at two surfaces in 3-dimensional space. The formula provided corresponds to the case of finite transversal stabilization rate.
The purpose of this paper is to provide equations to model the evolution of effective diffusion over a Riemannian fiber bundle (under the hypothesis of infinite diffusion rate along compact fibers). These equations are obtained by projecting the diffusion equation onto the base manifold of the fiber bundle. The projection (or dimensional reduction) is achieved by integrating the diffusion equation along fibers of the bundle. This work generalizes an put into a general framework previous work on effective diffusion over channels and the interfaces between curved surfaces.
The purpose of this paper is to provide new formulas for the effective diffusion coefficient of a generalized Fick-Jacobs equation for narrow 3-dimensional channels. The generalized Fick-Jacobs equation is obtained by projecting the 3-dimensional diffusion equation along the normal directions of a curve in three dimensional space that roughly resembles the narrow channel. The projection (or dimensional reduction) is achieved by integrating the diffusion equation along the cross sections of the channel contained in the planes orthogonal to the curve. We show that the resulting formula for the associated effective diffusion coefficient can be expressed in terms of the geometric moments of the channel's cross sections and the curve's curvature. We show the effect that a rotating cross section with offset has on the effective diffusion coefficient.
The purpose of this paper is to provide new formulas for the estimation of the effective diffusion coefficient of an equation of Fick-Jacob's type obtained by projecting the two-dimensional diffusion equation along the normal direction of an arbitrary plane curve.