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Frishfelds, Vilnis
Publications (10 of 39) Show all publications
Burström, P., Frishfelds, V., Ljung, A.-L., Lundström, T. S. & Marjavaara, D. (2017). Discrete and continuous modelling of convective heat transport in a thin porous layer of mono sized spheres (ed.). Heat and Mass Transfer, 53(1), 151-160
Open this publication in new window or tab >>Discrete and continuous modelling of convective heat transport in a thin porous layer of mono sized spheres
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2017 (English)In: Heat and Mass Transfer, ISSN 0947-7411, E-ISSN 1432-1181, Vol. 53, no 1, p. 151-160Article in journal (Refereed) Published
Abstract [en]

Convective heat transport in a relatively thin porous layer of monosized particles is here modeled. The size of the particles is only one order of magnitude smaller than the thickness of the layer. Both a discrete three-dimensional system of particles and a continuous one-dimensional model are considered. The methodology applied for the discrete system is Voronoi discretization with minimization of dissipation rate of energy. The discrete and continuous model compares well for low velocities for the studied uniform inlet boundary conditions. When increasing the speed or for a thin porous layer however, the continuous model diverge from the discrete approach if a constant dispersion is used in the continuous approach. The new result is thus that a special correlation must be used when using a continuous model for flow perpendicular to a thin porous media in order to predict the dispersion in proper manner, especially in combination with higher velocities.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-9656 (URN)10.1007/s00231-016-1792-7 (DOI)000391384700014 ()2-s2.0-84962175661 (Scopus ID)85295f62-d81d-468a-a26b-53cc1547fcd2 (Local ID)85295f62-d81d-468a-a26b-53cc1547fcd2 (Archive number)85295f62-d81d-468a-a26b-53cc1547fcd2 (OAI)
Note

Validerad; 2017; Nivå 2; 2017-03-15 (inah)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-09-27Bibliographically approved
Frishfelds, V., Hellström, J. G. & Lundström, T. S. (2014). Flow-induced deformations within random packed beds of spheres (ed.). Paper presented at . Transport in Porous Media, 104(1), 43-56
Open this publication in new window or tab >>Flow-induced deformations within random packed beds of spheres
2014 (English)In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 104, no 1, p. 43-56Article in journal (Refereed) Published
Abstract [en]

Low Reynolds number flow-induced alterations of permeability of random packing of mono-sized spheres is studied. The number of spheres is several thousands and the porosities ranges between 0.4 and 0.6. The change of permeability is obtained for elastic deformations of the positions of the spheres using either of two methods. Each sphere is elastically attached to single points or the spheres that are connected via an elastic porous network. The system of spheres is divided into smaller volumes with Voronoi diagrams and the flow is derived by usage of a dual stream function. The local saturated flow fields are approximated as for close packed spheres and the overall flow pattern is obtained by minimising the dissipation rate of energy. The results show that the permeability for large random systems increases as a function of velocity and thus the deformation. The alteration is, however, much less than for two-dimensional cases like parallel cylinders. The relative increase in permeability becomes larger as the porosity increases from 0.4 to 0.6.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-6051 (URN)10.1007/s11242-014-0319-2 (DOI)000338842500003 ()2-s2.0-84903893242 (Scopus ID)43eb4508-9027-4312-8fb8-e59d9e2adcbe (Local ID)43eb4508-9027-4312-8fb8-e59d9e2adcbe (Archive number)43eb4508-9027-4312-8fb8-e59d9e2adcbe (OAI)
Note
Validerad; 2014; 20140420 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Burström, P., Frishfelds, V., Ljung, A.-L., Lundström, T. S. & Marjavaara, D. (2014). Grate aerodynamic: Model strategies for gas flow through a 2D iron ore pellet bed (ed.). Paper presented at European Fluid Mechanics Conference : 14/09/2014 - 18/09/2014. Paper presented at European Fluid Mechanics Conference : 14/09/2014 - 18/09/2014.
Open this publication in new window or tab >>Grate aerodynamic: Model strategies for gas flow through a 2D iron ore pellet bed
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2014 (English)Conference paper, Oral presentation only (Refereed)
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-29976 (URN)39eac0f2-feca-4a34-9a2a-a497a9459101 (Local ID)39eac0f2-feca-4a34-9a2a-a497a9459101 (Archive number)39eac0f2-feca-4a34-9a2a-a497a9459101 (OAI)
Conference
European Fluid Mechanics Conference : 14/09/2014 - 18/09/2014
Note
Godkänd; 2014; 20140923 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-12-01Bibliographically approved
Jourak, A., Frishfelds, V., Hellström, J. G. & Lundström, T. S. (2014). Numerical derivation of dispersion coefficients for flow through three-dimensional randomly packed beds of monodisperse spheres (ed.). Paper presented at . AIChE Journal, 60(2), 749-761
Open this publication in new window or tab >>Numerical derivation of dispersion coefficients for flow through three-dimensional randomly packed beds of monodisperse spheres
2014 (English)In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 60, no 2, p. 749-761Article in journal (Refereed) Published
Abstract [en]

The longitudinal (DL) and transverse (DT) dispersion coefficients for flow through randomly packed beds of discrete monosized spherical particles are studied. The three-dimensional (3-D) porous-medium model consists of thousands of spherical particles that are divided into cells using Voronoi diagrams. The relationship between the variation of the dual stream function and the vorticity between neighboring particles is derived using Laurent series. The whole flow pattern at low particle Reynolds number is then obtained by minimization of the dissipation rate of energy with respect to the dual stream function. The DL is obtained by fitting the resulting effluent curve to a 1-D solution of a continuous model. The DT is obtained by fitting the numerical concentration profile to an approximate 2-D solution. The derived DL and DT values are in agreement with 3-D experimental data from the literature enabling a study of the effects of pore structure and porosity on DL and DT.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-4371 (URN)10.1002/aic.14284 (DOI)000329484200030 ()2-s2.0-84892445978 (Scopus ID)25049d43-29e3-4452-9cad-57eafebe902e (Local ID)25049d43-29e3-4452-9cad-57eafebe902e (Archive number)25049d43-29e3-4452-9cad-57eafebe902e (OAI)
Note
Validerad; 2014; 20131031 (gunhel)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Jourak, A., Frishfelds, V., Hellström, J. G., Lundström, T. S., Herrmann, I. & Hedström, A. (2013). Longitudinal dispersion coefficient: effects of particle-size distribution (ed.). Paper presented at . Transport in Porous Media, 99(1), 1-16
Open this publication in new window or tab >>Longitudinal dispersion coefficient: effects of particle-size distribution
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2013 (English)In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 99, no 1, p. 1-16Article in journal (Refereed) Published
Abstract [en]

The effects of particle-size distribution on the longitudinal dispersion coefficient (DL) in packed beds of spherical particles are studied by simulating a tracer column experiment. The packed-bed models consist of uniform and different-sized spherical particles with a ratio of maximum to minimum particle diameter in the range of 1–4. The modified version of Euclidian Voronoi diagrams is used to discretize the system of particles into cells that each contains one sphere. The local flow distribution is derived with the use of Laurent series. The flow pattern at low particle Reynolds number is then obtained by minimization of dissipation rate of energy for the dual stream function. The value of DL is obtained by comparing the effluent curve from large discrete systems of spherical particles to the solution of the one-dimensional advection-dispersion equation. Main results are that at Peclet numbers above 1, increasing the width of the particle-size distribution increases the values of DL in the packed bed. At Peclet numbers below 1, increasing the width of the particle-size distribution slightly lowers DL.

National Category
Fluid Mechanics and Acoustics Water Engineering
Research subject
Fluid Mechanics; Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-14471 (URN)10.1007/s11242-013-0159-5 (DOI)000321661600001 ()2-s2.0-84877642038 (Scopus ID)dd5b2cce-0d86-4315-9804-903adf1ee0a2 (Local ID)dd5b2cce-0d86-4315-9804-903adf1ee0a2 (Archive number)dd5b2cce-0d86-4315-9804-903adf1ee0a2 (OAI)
Note
Validerad; 2013; 20130410 (amijou)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lundström, T. S. & Frishfelds, V. (2013). Modeling filtration of particulate flow during impregnation of dual-scale fabrics (ed.). Paper presented at . Journal of composite materials, 47(15), 1907-1915
Open this publication in new window or tab >>Modeling filtration of particulate flow during impregnation of dual-scale fabrics
2013 (English)In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 47, no 15, p. 1907-1915Article in journal (Refereed) Published
Abstract [en]

Filtration of particles during impregnation of dual-scale fabrics is studied numerically for a number of geometries and initial positions of the particles by improving a previously derived model for a high density of the particles. The initial position and size of the particles are varied. The main result is that structural composites can be tailor-made as to additional properties by such an approach

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-14971 (URN)10.1177/0021998312452026 (DOI)000320701300010 ()2-s2.0-84879470089 (Scopus ID)e6c0e880-3cb6-41d3-9a62-0b560b2cabc4 (Local ID)e6c0e880-3cb6-41d3-9a62-0b560b2cabc4 (Archive number)e6c0e880-3cb6-41d3-9a62-0b560b2cabc4 (OAI)
Note
Validerad; 2013; 20120527 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Jourak, A., Frishfelds, V., Lundström, T. S., Herrmann, I. & Hedström, A. (2013). The calculations of dispersion coefficients inside two-dimensional randomly packed beds of circular particles (ed.). Paper presented at . AIChE Journal, 59(3), 1002-1011
Open this publication in new window or tab >>The calculations of dispersion coefficients inside two-dimensional randomly packed beds of circular particles
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2013 (English)In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 59, no 3, p. 1002-1011Article in journal (Refereed) Published
Abstract [en]

The longitudinal (DL) and transverse (DT) dispersion coefficients in two-dimensional (2D) randomly packed beds of circular particles in a laminar flow regime are derived. A 2D discrete system of particles is divided into cells using modified Voronoi diagrams. The relationship between the variation of the stream function and the averaged vortictiy is obtained from Computational Fluid Dynamics simulations. The whole flow pattern is then obtained by using the principle of energy dissipation rate minimization. The obtained values of DL agree well with 3D experimental data for all velocities investigated. At very high velocities, DT in 2D appears to be higher than 3D experimental data. In addition, the effects of particle size distribution, packing structure, and porosity on the DL and DT were studied. One result was that an increase in the width of the particle size distribution resulted in higher values of DL and DT at high velocities.

National Category
Fluid Mechanics and Acoustics Water Engineering
Research subject
Fluid Mechanics; Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-15564 (URN)10.1002/aic.13867 (DOI)000317465700029 ()2-s2.0-84874550203 (Scopus ID)f189f5ee-4d38-4284-9091-cb7ca93e65a2 (Local ID)f189f5ee-4d38-4284-9091-cb7ca93e65a2 (Archive number)f189f5ee-4d38-4284-9091-cb7ca93e65a2 (OAI)
Note
Validerad; 2013; 20120604 (amijou)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lundström, T. S., Hellström, J. G. & Frishfelds, V. (2013). Transversal flow-induced deformation of fibres during composites manufacturing and the effect on permeability (ed.). Paper presented at . Journal of reinforced plastics and composites (Print), 32(15), 1129-1135
Open this publication in new window or tab >>Transversal flow-induced deformation of fibres during composites manufacturing and the effect on permeability
2013 (English)In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 32, no 15, p. 1129-1135Article in journal (Refereed) Published
Abstract [en]

Low Reynolds number flow of a viscous fluid through bundles in non-crimp stitched fabrics is considered for different arrangements of the fibres within the bundles. Using a previous derived model, two-dimensional Navier–Stokes solutions are sampled for the flow between a few fibres with a subsequent minimisation of the dissipation rate in the total system of fibres. Based on the detailed geometry of the fabrics flow induced elastic deformations of the fibre bundles are then derived and the overall permeability is computed for different pressure gradients. The permeability of random arrays of a large number of as well mono-dispersed as poly-dispersed fibres increases as the flow-induced deformation increases and despite the relative shift of the fibres is small the overall change in permeability is essential. For a system with gaps between bundles the change in permeability depends on the orientation of the flow field with respect to the geometry studied while for a regular packing the alteration in permeability is negligible.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-4022 (URN)10.1177/0731684413491846 (DOI)000321827400006 ()2-s2.0-84880409744 (Scopus ID)1e095bee-a30c-4809-afbe-43bc7b8223d6 (Local ID)1e095bee-a30c-4809-afbe-43bc7b8223d6 (Archive number)1e095bee-a30c-4809-afbe-43bc7b8223d6 (OAI)
Note
Validerad; 2013; 20130126 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Jourak, A., Frishfelds, V., Hellström, J. G. & Lundström, T. S. (2012). Derivation of dispersion coefficients in large random arrays of spheres and cylinders (ed.). Paper presented at European Fluid Mechanics Conference : 09/09/2012 - 13/09/2012. Paper presented at European Fluid Mechanics Conference : 09/09/2012 - 13/09/2012.
Open this publication in new window or tab >>Derivation of dispersion coefficients in large random arrays of spheres and cylinders
2012 (English)Conference paper, Oral presentation only (Refereed)
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-31172 (URN)544a2964-6a25-48a3-877b-83ac59e9021c (Local ID)544a2964-6a25-48a3-877b-83ac59e9021c (Archive number)544a2964-6a25-48a3-877b-83ac59e9021c (OAI)
Conference
European Fluid Mechanics Conference : 09/09/2012 - 13/09/2012
Note
Godkänd; 2012; 20121030 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Ljung, A.-L., Frishfelds, V., Lundström, T. S. & Marjavaara, D. (2012). Discrete and continuous modelling of heat and mass transport in drying of a bed of iron ore pellets (ed.). Paper presented at . Drying Technology, 30(7), 760-773
Open this publication in new window or tab >>Discrete and continuous modelling of heat and mass transport in drying of a bed of iron ore pellets
2012 (English)In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 30, no 7, p. 760-773Article in journal (Refereed) Published
Abstract [en]

Drying of a porous bed of iron ore pellets is here considered by modeling a discrete two-dimensional system of round pellets. As a complement to the two-dimensional model, a continuous one-dimensional model enabling fast calculations is developed. Results from the discrete model show that the temperature front advances faster in areas with large distances between the pellets. In areas with low flow speed, the temperature of the pellets increases with a relatively slow rate. The water inside these pellets will therefore remain for a long time. The continuous model fits the discrete model very well for a regular distribution of equal-sized particles. A discrete model with irregular packing will, compared to the continuous model, show a larger variation in the distribution of temperature and moisture content in the final phase of drying.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-3596 (URN)10.1080/07373937.2012.662567 (DOI)000303236100008 ()2-s2.0-84860202254 (Scopus ID)16c17696-70da-4f9b-abf9-b15454244f39 (Local ID)16c17696-70da-4f9b-abf9-b15454244f39 (Archive number)16c17696-70da-4f9b-abf9-b15454244f39 (OAI)
Note
Validerad; 2012; 20120215 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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