The kinetic of the heterogeneous chemical reaction of aluminum hydroxide and fluosilicic acid was studied. It was found that the diffusion of the reactants through the porous silica coating to the aluminum hydroxide surface and the interfacial chemical reaction between the diffusing reactant and aluminum hydroxide platelets control the overall reaction rate. These two phenomena were studied...

In this study, the modeling of hydrogen production process in microreactors by methanol-steam reforming reaction is investigated. The catalytic reaction of methanol-steam reforming producing hydrogen is simulated considering a 3D geometry for the microreactor. To calculate diffusion among species, mixture average correlations are compared to Stephan-Maxwell equations. The reactions occurring in...

Chaotic mixing of distinct fluids produces a convoluted structure to the interface separating these fluids. For miscible fluids (as considered here), this interface is defined as a 50% mass concentration isosurface. For shock wave induced (RichtmyerMeshkov) instabilities, we find the interface to be increasingly complex as the computational mesh is refined. This interfacial chaos is cut off by ...

The advantage of front tracking over capturing methods for the numerical simulation of discontinuity surfaces in fluid flow is to eliminate the numerical diffusion of mass across a fluid interface. For accurate modeling of an interface between miscible fluids, however, physical mass diffusion may be significant, and must be added to the calculation. The main purpose of this paper is to introduc...

AIMS AND BACKGROUND The aim of the study was to define the role of diffusion-weighted imaging in the characterization of adnexal complex masses, with particular regard to the distinction between benign and malignant lesions. Conflicting results on this topic have emerged from studies in the last decade, with a consequent substantial limitation to the use of this relatively novel technique in cl...

We investigate numerically the combined effects of supersonic turbulence, strong magnetic fields and ambipolar diffusion on cloud evolution leading to star formation. We find that, in clouds that are initially magnetically subcritical, supersonic turbulence can speed up star formation, through enhanced ambipolar diffusion in shocks. The speedup overcomes a major objection to the standard scenar...

By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes’ drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities such as the asymptotic speed of the center of mass or the effective diffusion coefficient. Using an equivalent tilted ratchet model, we observe that the...

The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of N(p) spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can b...

Unsteady flow with magneto-hydrodynamics and heat generation through porous medium past an impulsively started vertical plate with constant wall temperature and mass diffusion is considered here. The effect studied is a combination of Hall current and chemical reaction. The motivation behind this study is the applications of such kind of problems in industry. In many industrial applications ele...

The mass transport, accompanied by chemical reaction through membrane reactor has been investigated in the case of varying diffusion coefficient and solubility coefficient. In the reality, both parameters might depend on the concentration and/or on the inhomogeneity of the membrane layer. General mathematical models were developed to describe the mass transport, taking into account the external...