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Characterizing flow resistance in 3-dimensional disordered fibrous structures based on Forchheimer coefficients for a wide range of Reynolds numbers
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0002-5864-4576
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. (Miljö- och energisystem)
2016 (English)In: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 40, no 21-22, 8898-8911 p.Article in journal (Refereed) Published
Abstract [en]

The flow resistance in 3-dimensional fibrous structures are investigated in particle Reynolds number representing flow characteristics with strong inertia. The resistance coefficients are established based on steady state simulations of single-phase processes of water numerically. An automatized simulation process in COMSOL is developed with a MATLAB algorithm in which production runs could be carried for various 3-dimensional fibrous structures. Simulation of flow processes ranging from Reynolds numbers at creeping flow levels to high Reynolds number at approximately 1000 are calculated and a numerical data set is established in order to estimate Forchheimer coefficients which are used to correlate a dimensionless friction factor to a modified Reynolds expression for porous media.

The friction factor and dimensionless permeability are calculated for fibrous structures with (i) disordered unidirectional fibers (ii) an isotropic fiber orientation in-plane perpendicular to the flow, and (iii) an isotropic fiber structure in a the 3-dimensional space. Empirical correlations of the friction factor and Reynolds number are used to compare our simulation data in order to assess the validity of our models and flow resistance estimations. The dimensionless permeability is moreover compared to other numerical simulations of flow through fibrous structures in order to assess flow resistance at low Reynolds number.

It is concluded that flow resistance in the isotropic fiber arrangement in space is lower than the in-plane isotropic orientation and disordered unidirectional fiber arrangements at creeping flow conditions, however, all friction actors converges towards the same value at higher Reynolds numbers indicating that fiber orientation is independent at high inertia flow regimes. Overall, our numerical simulations agree well to classical empirical formulations for a wide range of Reynolds number. However, the comparison differs considerably depending on the porosity level.

Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 40, no 21-22, 8898-8911 p.
Keyword [en]
Flow resistance; Volume-averaging; Porous media; Forchheimer coefficients; Friction factor; Fibrous structure
National Category
Fluid Mechanics and Acoustics
Research subject
Environmental and Energy Systems
Identifiers
URN: urn:nbn:se:kau:diva-46411DOI: 10.1016/j.apm.2016.05.036ISI: 000384853900005OAI: oai:DiVA.org:kau-46411DiVA: diva2:1033201
Note

This article was published as manuscript in Kamal Rezk thesis.

Available from: 2016-10-06 Created: 2016-10-06 Last updated: 2016-12-07Bibliographically approved
In thesis
1. Methods for Reducing the Complexity of Geometrical Structures Based on CFD Programming: Time Efficient Simulations Based on Volume Forces Coupled with Single and Two-phase Flow
Open this publication in new window or tab >>Methods for Reducing the Complexity of Geometrical Structures Based on CFD Programming: Time Efficient Simulations Based on Volume Forces Coupled with Single and Two-phase Flow
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Throughout recent years, computer based programs have been applied to solve and analyse industrial problems encountered global fields such as automobile design for reduction of CO2-gas, designing wind parks aimed at increasing power output etc. One of these developed programs is Computational Fluid Dynamics (CFD) which numerically solves complex flow behaviour based on computer power.

As there is an ongoing expansion of CFD usage in industry, certain issues need to be addressed as they are becoming more frequently encountered. The general demand for the simulation of larger control volumes and more advanced flow processes result in an extensive requirement of computer resources. Moreover, the implementation of commercial CFD codes in small-scaled industrial companies seems to generally be utilised as a black box based on the knowledge of fluid mechanic theory. Increased partnerships between industry and the academic world involving various CFD based design processes generally yield to a verbal communication interface, which is a crucial step in the process given the level of dependency between both sides.

Based on these notions, a method for establishing time efficient CFD-models with implementation of volume forces as sink terms in the momentum equation is presented. The internal structure, or parts of the structure, in the simulation domain is removed which reduces the geometrical complexity and along with it, computational demand.  These models are the basis of assessing the benefits of utilizing a numerical based design process in industry in which the CFD code is used as a communication tool for knowledge sharing with counterparts in different fields.

Abstract [en]

As there is an ongoing expansion of CFD usage in industry, certain issues need to be addressed as they are becoming more frequently encountered. The general demand for the simulation of larger control volumes and more advanced flow processes result in an extensive requirement of computer resources. Moreover, the implementation of commercial CFD codes in small-scaled industrial companies seems to generally be utilised as a black box based on the knowledge of fluid mechanic theory. Increased partnerships between industry and the academic world involving various CFD based design processes generally yield to a verbal communication interface, which is a crucial step in the process given the level of dependency between both sides.

Based on these notions, a method for establishing time efficient CFD-models with implementation of volume forces as sink terms in the momentum equation is presented. The internal structure, or parts of the structure, in the simulation domain is removed which reduces the geometrical complexity and along with it, computational demand.  These models are the basis of assessing the benefits of utilizing a numerical based design process in industry in which the CFD code is used as a communication tool for knowledge sharing with counterparts in different fields.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2014. 104 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2014:32
Keyword
Numerical design cycle, CFD, porous media, volume forces, heat exchanger, vacuum dewatering, time efficient simulations
National Category
Fluid Mechanics and Acoustics
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-31983 (URN)978-91-7063-565-6 (ISBN)
Public defence
2014-06-09, 9C 204, Universitetsgatan 2, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2014-05-19 Created: 2014-04-25 Last updated: 2016-10-06Bibliographically approved

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