slow sand filters are as a proper technology for pre-treatment of raw water, with a fine and medium trubidity in small communities in developing countries. thus, with a minimum operation cost and minimum need for expest bodies have the maximum efficiency. the purpose of this research is carried out to evaluate the efficiency of two processes of horizontal flow roughing filter and vertical flow ...

Three-dimensional hydrostratigraphic models created using multiple-point geostatistics promise to help quantify the role of preferential flow paths in a h eterogeneous glacially-deposited aquitard. The preferential flow paths allow for faster transport of fluids and solutes than in the surrounding matrix. Transport in preferential flow paths is governed by the hydraulic properties within the fl...

In our present research, we focus on the modeling of airflow related to natural disasters, such assand accumulation, with urban form studies. The objective is to find which urban form can promote sand passing andreduce as much as possible stagnation of sand in the building area (streets, alleys, etc.). The urban form design will bediscussed through the simulation of airflow by using Computation...

We investigated the effect of different flow conditions on the transport of bacteriophage phiX174 in Memphis aquifer sand. Virus transport associated with a wetting front moving into an initially unsaturated horizontal sand column was experimentally compared with that observed under steady-state saturated vertical flow. Results obtained by sectioning the sand columns showthattotal (retained and...

This paper discusses the possibilities of laboratory simulation of large-scale flow around dunes, both with and without saltation, and the study of the physics of the small-scale particle motion occurring on a sand surface composed of like-moveable particles. Physics of the atmospheric boundary layer are presented in the context of laboratory applications. The governing equations of fluid and/o...

The construction industry is the largest consumer of natural resources which led to depletion of good quality natural sand (Fine aggregates). This situation led us to explore alternative materials and granular slag a waste industrial byproduct is one such material identified for utilization it as replacement of natural sand. This paper highlights upon the feasibility study for the utilization o...

the permeability and tortuosity of pore-scale two and three-dimensional random porous media were calculated using the lattice boltzmann method (lbm). effects of geometrical parameters of medium on permeability and tortuosity were investigated as well. two major models of random porous media were reconstructed by computerized tomography method: randomly distributed rectangular obstacles in a uni...

measuring sensitivity of hydraulic structures is considered as an approach for evaluation of water projects performance, due to lower distribution efficiency in irrigation and drainage project schemes. sensitivity analysis approach for irrigation structures is one of flow analysis methods which are developed in recent years in order to measure the behavior of flow in hydraulic structures in an ...

In the context of simulating the frictional contact dynamics of large systems of rigid bodies, this paper reviews a novel method for solving large cone complementarity problems by means of a fixed-point iteration algorithm. The method is an extension of the Gauss-Seidel and Gauss-Jacobi methods with overrelaxation for symmetric convex linear complementarity problems. Convergent under fairly sta...