The viscosity or, more precisely, the rheological behavior of colloidal suspensions is most sensitive to the overall properties of both the particles (mainly size and shape) and their double layers (surface charge and double layer thickness). The mere presence of uncharged colloids alters the ̄ow ®eld in such a way that the apparent dynamic viscosity of the suspension, g, is larger than that of ...

In this paper we study the sedimentation of several thousand circular particles in 2D using the method of distributed Lagrange multipliers for solid-liquid ow. The simulation gives rise to ngering which resembles Rayleigh-Taylor instabilities. The waves have a well de ned wavelength and growth rate which can be modeled as a conventional Rayleigh-Taylor instability of heavy uid above light. The ...

We develop an ELLAM (Eulerian-Lagrangian localized adjoint method) scheme to solve twodimensional advection-dispersion equations with all combinations of in ow and out ow Dirichlet, Neumann, and ux boundary conditions. The ELLAM formalism provides a systematic framework for implementation of general boundary conditions, leading to mass-conservative numerical schemes. The computational advantage...

We consider an extended mixed nite element formulation for groundwater ow and transport problems with either a tensor hydraulic conductivity or a tensor dispersion. While the aquifer domain can be geometrically general, in our formulation the computational domain is rectangular. The approximating spaces for the mixed method are deened on a smooth curvilinear grid, obtained by a global mapping o...

The Lagrangian transport element method for the solution of axisymmetric constant-density ow is extended to variable-density ow. In this method, thin vortex ring-elements of the Rankine type are used to discretize the vorticity eld as well as the density gradient eld. At the axis, since the ring element concept does not apply, several Hill's spherical vortices are used. A simple algebraic expre...

Reliable estimates of river stream fl ow and fl ood zoning maps are needed for water resourcesmanagement such as fl ood mitigation, water supply, dam construction and irrigation. Flood zoning needsaccurate data and is one of the non-structural fl ood management methods. This paper describes theapplication of HEC-RAS and GIS model to determine fl oodplains maps for the part of Sardabrud Rivertha...

We propose a novel optical wireless (OW) configuration that employs a line strip multibeam transmitter (LSMT) in conjunction with a narrow field-of-view (FOV) direction diversity receiver. Such a configuration overcomes the drawbacks and combines the advantages of both types of optical wireless links namely line-of-sight and diffuse links. The main target is to combat the effect of multipath di...

340 Numerical modeling approaches for multiphase fl ow and tracer or chemical transport in porous media are generally based on methodologies developed for reservoir simulation and groundwater modeling. They involve solving coupled massconservation equations that govern the transport processes of all chemical components in isothermal and nonisothermal subsurface systems using fi nite-difference ...