Thesis-2005-Ting.pdf (15.94 MB)
Three dimensional finite element modelling of non-Newtonian fluid flow through a wire mesh
thesis
posted on 2013-08-14, 13:14 authored by Kee Chien TingMonofilament cloths are used as the separation media in filtration; woven wire
cloths or screens are also used as the media in filters or to enhance the integrity of
the filter medium in, for example, filter cartridges. A better understanding of the
flow pattern in the woven structure is essential in examining the initial stages of
cake filtration as well as the effect of weaves on fouling phenomena within a filter
cloth.
Due to the complex geometry of a woven cloth, three-dimensional modelling is
necessary to correctly visualize the structure of the flow and hence to predict
pressure losses. The modelling in a three-dimensional domain was handled using a
finite element method which is known to cope with flow domains in complex
geometries very effectively. The governing equations of continuity and momentum
were solved by a mixed U-V-W-P finite element method and in conjunction with a
first order Taylor-Galerkin scheme for temporal discretization. A secondary
solution scheme based on a continuous Penalty finite element method in conjunction
with theta time stepping method was also used to solve the governing equations.
Two robust and reliable computer tools based on these sound and robust numerical
techniques have been developed to simulate Newtonian and non-Newtonian fluid
flow through a woven wire mesh. Purpose-designed test cases were used to validate
the capability of the developed algorithms and were found to give expected
numerical predictions.
A selection of domains was used to investigate the effect of weave pattern, aperture
to diameter ratio and Reynolds number on flow pattern and pressure drop. Based on
these domains, simulations were successfully conducted to investigate fluid flow
through four basic pore types in a plain weave, twill weave and satin weave. The
flow fields in the interstices were illustrated using a commercial graphics software
package. The results showed that the weave pattern has a profound effect on the
fluid flow pattern and pressure drop across the wire mesh. Simulation results
showed that plain weave gives the lowest pressure drop, while satin weave gives the
highest pressure drop across the woven cloths.
Fluid flow through a plain weave was further investigated in conjunction with the
experimental studies of Rushton (1969) using water and Chhabra and Richardson
(1985) using shear-thinning fluids. Simulations were tested against experimental
data extracted from both studies. The close agreement of the results to those of the
available experimental data in literature showed the accuracy and the reliability of
the predictions.
Personal communication with industrial experts and woven cloth manufacturers
have confirmed industrial practice, whereby a plain weave is primarily used due to
its lowest flow resistance. This showed that the developed model is capable of
generating accurate results for flow of both Newtonian and non-Newtonian fluids
through filter media. The model can be used by design engineers as a convenient
and effective Computer Aided Design (CAD) tool for quantifying effects of pressure
drop. The model can also be extended to describe particle capture on/in the wire
mesh and woven filter cloths.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Chemical Engineering
Publisher
© Kee Chien TingPublication date
2005Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough UniversityEThOS Persistent ID
uk.bl.ethos.419896Language
- en