Navraj Hanspal

NUMERICAL ANALYSIS OF MEDIUM COMPRESSION AND LOSSES IN FILTRATION AREA IN PLEATED MEMBRANE CARTRIDGE FILTERS

A computer model has been developed to simulate the fluid flow in pleated filter cartridges. This model has been used to evaluate the performance and design of pleated cartridge membrane filters. The effects of medium compression, pleat deformation, and pleat crowding are analyzed. At higher flow rates due to the exerted fluid pressure the medium is deformed, which leads to a reduction in the material permeability. Further, due to pleating and bending there is a loss in effective filtration area. The combined effects of compression and reduction in filtration area cause deviations from Darcys law. To interpret such deviations, permeability models based on the data obtained from the flat sheets of the filter material used in cartridge fabrication have been developed. The incorporation of the permeability model within the main hydrodynamic model determines the percentage loss in filtration area, percentage medium compression, and the pressure drop across the filters. Results of this study have been presented for fiberglass medium. The simulated results have been compared against experimental industrial data for purposes of model validation. The developed simulation tool offers a robust, cost-effective, and user-friendly design and analysis tool for pleated cartridge membrane filters, which can be easily used by engineers in industry.

Numerical Analysis of Rubber Moulding Using Finite Element Modelling

Abstract Finite element technique is used to model the free surface flow regime representing injection mould filling of elastomeric material such as rubber compounds. The most distinct feature of the constitutive behaviour of elastomers, is the influence of material elasticity on the elongation and shear deformation suffered by the fluid during flow. In the present study this feature has been tackled through the use of Criminale-Erickson-Fibley (CEF) model. A scheme based on the Volume of Fluid technique is developed for free surface tracking. The results represented in this paper have also been compared against the Phan-Thien/Tanner model and are shown to be in closer agreement with the theoretical expectations than those obtained by the P-T/T equation. The results prove the applicability of the developed model to industrially relevant situations.

A numerical study of the hydrodynamic conditions in coupled free and heterogeneous porous domains

The existence of a free flow domain adjacent to a porous medium is a common occurrence in many environmental and petroleum engineering problems. The porous media may often contain various forms of heterogeneity, e.g., layers, fractures, micro-scale lenses, etc. These heterogeneities affect the pressure distribution within the porous domains. This, in turn, may influence the hydrodynamic conditions at the free/porous domain interface and, hence, the combined flow behaviour. Under steady-state conditions, the heterogeneities are known to have negligible effects on the combined flow behaviour. However, the significance of the heterogeneity effects on coupled free and porous flow under transient conditions is not certain. In this work, numerical simulations have been carried out to investigate the effects of heterogeneity in porous media on the hydrodynamics conditions on determining the behaviour of combined free and porous regimes. The coupling of the governing equations of motion in free and porous domains has been achieved through the well known Beavers and Joseph interfacial condition. Of special interests in this work are the porous domains with flow-through ends. They represent the general class of problems where large physical domains are truncated to smaller sections for ease of mathematical analysis. However, this causes a practical difficulty in modelling such systems. This is because the information on flow behaviour, i.e., boundary conditions at the truncated sections, is usually not available. Use of artificial boundary conditions to solve these problems effectively implies imposition of conditions, which do not necessarily match with the solutions required for the interior of the domain. This difficulty is resolved in this work by employing ‘stress free boundary conditions’ at the open end of the domains, which have been shown to provide accurate results by a number of previous authors. Heterogeneity in the porous media is introduced by defining a domain composed of two layers of porous media with different values of intrinsic permeability.