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Publications (10 of 34) Show all publications
Forslund, T. O. .., Larsson, I. A., Hellström, J. G. & Lundström, T. S. (2023). Steady-State Transitions in Ordered Porous Media. Transport in Porous Media, 149(2), 551-577
Open this publication in new window or tab >>Steady-State Transitions in Ordered Porous Media
2023 (English)In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 149, no 2, p. 551-577Article in journal (Refereed) Published
Abstract [en]

Previously performed experiments on flow through an ordered porous media cell with tomographic particle image velocimetry reveal a complex three-dimensional steady-state flow pattern. This flow pattern emerge in the region where inertial structures have been previously reported for a wide range of packings. The onset of these steady-state inertial flow structures is here scrutinized for three different types of packing using a finite difference method. It is concluded that the onset of the flow structure coincides with a symmetry break in the flow field and discontinuities in the pressure drop, volume averaged body forces and heat transfer. A quantity for identifying the transition is proposed, namely the pressure integral across the solid surfaces. It is also shown that the transition can both increase and decrease the heat transfer dependent on the actual geometry of the porous medium.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
FDM, Pore scale, Ordered porous media, Inertial transition
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-93182 (URN)10.1007/s11242-023-01966-w (DOI)001008440200001 ()2-s2.0-85161891565 (Scopus ID)
Funder
Swedish Research Council, 2017-04390
Note

Validerad;2023;Nivå 2;2023-08-15 (hanlid);

This article has previously appeared as a manuscript in a thesis.

Licens fulltext: CC BY License

Available from: 2022-09-22 Created: 2022-09-22 Last updated: 2023-09-05Bibliographically approved
Barcot, A., Åkerstedt, H. O., Larsson, I. A. & Lundström, S. (2023). Stormwater Uptake in Sponge-Like Porous Bodies Surrounded by a Pond: A Fluid Mechanics Analysis. Water, 15(18), Article ID 3209.
Open this publication in new window or tab >>Stormwater Uptake in Sponge-Like Porous Bodies Surrounded by a Pond: A Fluid Mechanics Analysis
2023 (English)In: Water, E-ISSN 2073-4441, Vol. 15, no 18, article id 3209Article in journal (Refereed) Published
Abstract [en]

In this work, a previously published model for the water up take of stormwater in sponge-like porous bodies by the group is further developed. This is done by investigating the highest-performing model and considering the water uptake from the surroundings of a pond and rain-infiltrated soil. This implies that water uptake from impermeable to partially permeable surfaces is examined. Hence, the following cases are considered: (1) impervious bottom surface and no precipitation, (2) impervious bottom surface with precipitation, (3) permeable soil with no precipitation, and (4) permeable soil with precipitation. A mathematical model covering all these cases is presented, where the governing equations are the mass conservation and Darcy’s law together with an assumption of a sharp wetting front being a first-order approximation of the complete Richard’s equation. Results for the water uptake height, pond depth, and wetting front are computed numerically and plotted against time. Analytical solutions are also presented in certain cases, and critical values are obtained. The parametric study includes variations in the ratio of the model- to the surrounding ground surface area, initial pond depth, precipitation, and soil characteristics. To exemplify, the time it takes to absorb the water from the pond after a precipitation period is presented. The results are related to the Swedish rainfall data of 1 h duration with a return period of 10 years. When evaluating efficiency, the focus is on the absorption time. Results vary considerably, demonstrating a general trend that with soil infiltration, the water absorption rate is higher. For most cases, the considered water amount is absorbed completely, although depending on the parameters and conditions. These results serve to optimize the model for each of the cases. The main focus of the research lies in the theoretical aspect.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
stormwater, porous media, water uptake, mathematical modelling, sharp wetting front, infiltration, water absorption
National Category
Water Engineering
Research subject
Fluid Mechanics; Centre - Centre for Stormwater Management (DRIZZLE)
Identifiers
urn:nbn:se:ltu:diva-101321 (URN)10.3390/w15183209 (DOI)
Funder
Vinnova
Note

Validerad;2023;Nivå 2;2023-09-12 (joosat);

CC BY 4.0 License

Available from: 2023-09-12 Created: 2023-09-12 Last updated: 2023-09-12Bibliographically approved
Forslund, T. O. M., Larsson, I. A., Hellström, J. G. & Lundström, T. S. (2022). A dual-lattice hydrodynamic-thermal MRT-LBM model implemented on GPU for DNS calculations of turbulent thermal flows. International journal of numerical methods for heat & fluid flow, 35(5), 1703-1725
Open this publication in new window or tab >>A dual-lattice hydrodynamic-thermal MRT-LBM model implemented on GPU for DNS calculations of turbulent thermal flows
2022 (English)In: International journal of numerical methods for heat & fluid flow, ISSN 0961-5539, E-ISSN 1758-6585, Vol. 35, no 5, p. 1703-1725Article in journal (Refereed) Published
Abstract [en]

Purpose

The purpose of this paper is to present a fast and bare bones implementation of a numerical method for quickly simulating turbulent thermal flows on GPUs. The work also validates earlier research showing that the lattice Boltzmann method (LBM) method is suitable for complex thermal flows.

Design/methodology/approach

A dual lattice hydrodynamic (D3Q27) thermal (D3Q7) multiple-relaxation time LBM model capable of thermal DNS calculations is implemented in CUDA.FindingsThe model has the same computational performance compared to earlier publications of similar LBM solvers. The solver is validated against three benchmark cases for turbulent thermal flow with available data and is shown to be in excellent agreement.

Originality/value

The combination of a D3Q27 and D3Q7 stencil for a multiple relaxation time -LBM has, to the authors’ knowledge, not been used for simulations of thermal flows. The code is made available in a public repository under a free license.

Place, publisher, year, edition, pages
Emerald Group Publishing Limited, 2022
Keywords
Lattice Boltzmann method, Turbulence, Thermal flows, Direct numerical simulation
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-93178 (URN)10.1108/HFF-06-2022-0339 (DOI)000893826100001 ()2-s2.0-85143219027 (Scopus ID)
Funder
Swedish Research Council, 2017-04390
Note

Validerad;2023;Nivå 2;2023-07-13 (sofila);

This article has previously appeared as a manuscript in a thesis

Available from: 2022-09-22 Created: 2022-09-22 Last updated: 2023-10-14Bibliographically approved
Larsson, I. S. (2022). The Aerodynamics of an Iron Ore Pelletizing Rotary Kiln. Fluids, 7(5), Article ID 160.
Open this publication in new window or tab >>The Aerodynamics of an Iron Ore Pelletizing Rotary Kiln
2022 (English)In: Fluids, E-ISSN 2311-5521, Vol. 7, no 5, article id 160Article in journal (Refereed) Published
Abstract [en]

This paper summarizes more than a decade of systematic studies of the flow field in an iron ore pelletizing rotary kiln using computational fluid dynamics (CFD) on simplified models of a real kiln. Physical, laser-based experiments have been performed to validate part of the numerical results. The objective is a better understanding of the kiln aerodynamics and, by extension, its effect on the combustion process. Despite all of the simplifications regarding the models studied in this project, the results show the importance of correctly predicting the flow field in order to optimize the combustion process. Combustion simulations revealed that the heat release from the flame does not affect or change the flow field in any significant way; the flow field, however, governs the flame propagation and affects the combustion process by controlling the mixing rates of fuel and air. Using down-scaled isothermal water models for investigating kiln aerodynamics in general and mixing properties in particular is therefore justified. Although the heat release from the flame cannot be accounted for in isothermal models, valuable implications regarding the real process can still be gained. To better model the actual process numerically, more advanced submodels for both the combustion and especially the flow field are needed. The complex flow field in this type of rotary kiln requires a careful choice of turbulence model to obtain accurate simulation results.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
rotary kiln, kiln aerodynamics, turbulence, mixing, combustion, CFD, experiments
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-90665 (URN)10.3390/fluids7050160 (DOI)000803176500001 ()2-s2.0-85130267975 (Scopus ID)
Funder
Vinnova, 2017-02170
Note

Validerad;2022;Nivå 2;2022-05-17 (johcin)

Available from: 2022-05-17 Created: 2022-05-17 Last updated: 2023-09-05Bibliographically approved
Andersson, L. R., Larsson, I. A., Hellström, J. G., Burman, A. J. & Andreasson, P. (2021). Localized roughness effects in non-uniform hydraulic waterways. Journal of Hydraulic Research, 59(1), 100-108
Open this publication in new window or tab >>Localized roughness effects in non-uniform hydraulic waterways
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2021 (English)In: Journal of Hydraulic Research, ISSN 0022-1686, E-ISSN 1814-2079, Vol. 59, no 1, p. 100-108Article in journal (Refereed) Published
Abstract [en]

Hydropower tunnels are generally subject to a degree of rock falls. Studies explaining this are scarce and the current industrial standards offer little insight. To simulate tunnel conditions, high Reynolds number flow inside a channel with a rectangular cross-section is investigated using Particle Image Velocimetry and pressure measurements. For validation, the flow is modelled using LES and a RANS approach with k - ε turbulence model. One wall of the channel has been replaced with a rough surface captured using laser scanning. The results indicate flow-roughness effects deviating from the standard non-asymmetric channel flow and hence, can not be properly predicted using spatially averaged relations. These effects manifest as localized bursts of velocity connected to individual roughness elements. The bursts are large enough to affect both temporally and spatially averaged quantities. Both turbulence models show satisfactory agreement for the overall flow behaviour, where LES also provided information for in-depth analysis.

Place, publisher, year, edition, pages
Taylor & Francis, 2021
Keywords
Hydropower, CFD, Validation, Hydraulic Roughness, PIV
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71098 (URN)10.1080/00221686.2020.1744744 (DOI)000549733600001 ()2-s2.0-85087934075 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-02-19 (alebob)

Available from: 2018-10-04 Created: 2018-10-04 Last updated: 2023-09-05Bibliographically approved
Åkerstedt, H. O., Lundström, T. S., Larsson, I. A., Marsalek, J. & Viklander, M. (2021). Modeling the Swelling of Hydrogels with Application to Storage of Stormwater. Water, 13(1), Article ID 34.
Open this publication in new window or tab >>Modeling the Swelling of Hydrogels with Application to Storage of Stormwater
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2021 (English)In: Water, E-ISSN 2073-4441, Vol. 13, no 1, article id 34Article in journal (Refereed) Published
Abstract [en]

The swelling effect in hydrogel bodies or sponge-like porous bodies (SPB) used in a specific stormwater storage concept of the down-flow type is considered. A macroscopic swelling model is proposed, in which water is assumed to penetrate into the hydrogel by diffusion described by diffusion equations together with a free-moving boundary separating the interface between the water and hydrogel. Such a type of problem belongs to the certain class of problems called Stefan-problems. The main objective of this contribution is to compare how the theoretical total amount of absorbed water is modified by the inclusion of swelling, when compared to the previously studied SPB devices analyzed only for the effect of diffusion. The results can be summarized in terms of the geometrical dimensions of the storage device and the magnitude of the diffusion coefficient D. The geometrical variables influence both the maximum possible absorbed volume and the time to reach that volume. The diffusion coefficient D only influences the rate of volume growth and the time to reach the maximum volume of stored water. The initial swelling of the hydrogel SPB grows with time (√Dt) until the steady state is reached and the swelling rate approaches zero. In all the cases considered, the swelling in general increases the maximum possible absorbed water volume by an amount of 14%.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
stormwater, storage, sponge-like porous media, swelling, hydrogel, modeling, Stefan-problem
National Category
Fluid Mechanics and Acoustics Water Engineering
Research subject
Fluid Mechanics; Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-82385 (URN)10.3390/w13010034 (DOI)000606764300001 ()2-s2.0-85098650254 (Scopus ID)
Funder
Vinnova, 2016-05176
Note

Validerad;2021;Nivå 2;2021-01-14 (alebob)

Available from: 2021-01-14 Created: 2021-01-14 Last updated: 2023-09-05Bibliographically approved
Forslund, T. O. M., Larsson, I. A., Lycksam, H., Hellström, J. G. & Lundström, T. S. (2021). Non-Stokesian flow through ordered thin porous media imaged by tomographic-PIV. Experiments in Fluids, 62(3), Article ID 46.
Open this publication in new window or tab >>Non-Stokesian flow through ordered thin porous media imaged by tomographic-PIV
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2021 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 62, no 3, article id 46Article in journal (Refereed) Published
Abstract [en]

The 3D flow-fields in a staggered and cubic arrangement of mono-radii cylinders are investigated using tomographic-PIV. The cylinder Reynolds-number is in the range of ≈10 to ≈800 giving an almost complete overview of the transition region. Two pore-scale effects are discovered. The first, visible in the cubic packing, is a spatially alternating lateral velocity field, which has a significant impact on the pressure drop and transversal dispersion. The second effect, present in the staggered array, is an example of a disturbance propagation effect that takes place in the laminar steady region; this manifests as a peculiar and complex flow-pattern. In accordance with other studies, it is shown that Darcy’s law can, from an engineering point of view be valid far beyond the limit for Stokesian flow.

Place, publisher, year, edition, pages
Springer, 2021
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-83513 (URN)10.1007/s00348-021-03140-8 (DOI)000626004100001 ()2-s2.0-85102048293 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-04-08 (alebob)

Available from: 2021-04-08 Created: 2021-04-08 Last updated: 2023-09-05Bibliographically approved
Larsson, I. A., Ljung, A.-L. & Marjavaara, B. D. (2021). Simulation of Thermal Effects on the Flow Field in a Pilot-Scale Kiln. Mining, Metallurgy & Exploration, 38(3), 1487-1495
Open this publication in new window or tab >>Simulation of Thermal Effects on the Flow Field in a Pilot-Scale Kiln
2021 (English)In: Mining, Metallurgy & Exploration, ISSN 2524-3462, Vol. 38, no 3, p. 1487-1495Article in journal (Refereed) Published
Abstract [en]

The flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Rotary kiln, Computational fluid dynamics (CFD), Coal combustion, Kiln aerodynamics
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-83889 (URN)10.1007/s42461-021-00422-x (DOI)000641639000001 ()2-s2.0-85106201890 (Scopus ID)
Funder
Vinnova, 2017-02170
Note

Validerad;2021;Nivå 2;2021-06-07 (johcin)

Available from: 2021-04-22 Created: 2021-04-22 Last updated: 2023-09-05Bibliographically approved
Forslund, T. O. M., Larsson, I. A., Hellström, J. G. & Lundström, T. S. (2021). The Effects of Periodicity Assumptions in Porous Media Modelling. Transport in Porous Media, 137(3), 769-797
Open this publication in new window or tab >>The Effects of Periodicity Assumptions in Porous Media Modelling
2021 (English)In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 137, no 3, p. 769-797Article in journal (Refereed) Published
Abstract [en]

The effects of periodicity assumptions on the macroscopic properties of packed porous beds are evaluated using a cascaded Lattice-Boltzmann method model. The porous bed is modelled as cubic and staggered packings of mono-radii circular obstructions where the bed porosity is varied by altering the circle radii. The results for the macroscopic properties are validated using previously published results. For unsteady flows, it is found that one unit cell is not enough to represent all structures of the fluid flow which substantially impacts the permeability and dispersive properties of the porous bed. In the steady region, a single unit cell is shown to accurately represent the fluid flow across all cases studied

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Porous media, Ordered porous media, Thin porous media, Lattice-Boltzmann method
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-78633 (URN)10.1007/s11242-021-01587-1 (DOI)000638527900001 ()2-s2.0-85104144564 (Scopus ID)
Funder
Swedish Research Council, 2017-04390
Note

Validerad;2021;Nivå 2;2021-05-03 (alebob)

Available from: 2020-04-23 Created: 2020-04-23 Last updated: 2023-09-05Bibliographically approved
Lundström, S., Åkerstedt, H. O., Larsson, S., Marsalek, J. & Viklander, M. (2020). Dynamic Distributed Storage of Stormwater in Sponge-Like Porous Bodies: Modelling Water Uptake. Water, 12(8), Article ID 2080.
Open this publication in new window or tab >>Dynamic Distributed Storage of Stormwater in Sponge-Like Porous Bodies: Modelling Water Uptake
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2020 (Swedish)In: Water, E-ISSN 2073-4441, Vol. 12, no 8, article id 2080Article in journal (Refereed) Published
Abstract [en]

An innovative concept of dynamic stormwater storage in sponge-like porous bodies (SPBs) is presented and modelled using first principles, for down-flow and up-flow variants of SPBs. The rate of inflow driven by absorption and/or capillary action into various porous material structures was computed as a function of time and found to be critically dependent on the type of structure and the porous material used. In a case study, the rates of inflow and storage filling were modelled for various conditions and found to match, or exceed, the rates of rainwater inflow and volume accumulation associated with two types of Swedish rainfalls, of 60-min duration and a return period of 10 years. Hence, the mathematical models indicated that the SPB devices studied could capture relevant amounts of water. The theoretical study also showed that the SPB concepts could be further optimized. Such findings confirmed the potential of dynamic SPB storage to control stormwater runoff and serve as one of numerous elements contributing to restoration of pre-urban hydrology in urban catchments. Finally, the issues to be considered in bringing this theoretical concept to a higher Technological Readiness Level were discussed briefly, including operational challenges. However, it should be noted that a proper analysis of such issues requires a separate study building on the current presentation of theoretical concepts.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
stormwater, storage, sponge-like, porous media, wetting, modelling, first principles, rainfall
National Category
Fluid Mechanics and Acoustics Water Engineering
Research subject
Fluid Mechanics; Urban Water Engineering; Centre - Centre for Stormwater Management (DRIZZLE)
Identifiers
urn:nbn:se:ltu:diva-80614 (URN)10.3390/w12082080 (DOI)000564662400001 ()2-s2.0-85089704735 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-08-31 (johcin)

Available from: 2020-08-31 Created: 2020-08-31 Last updated: 2023-09-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4916-9566

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