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Wigö, Hans
Publications (10 of 42) Show all publications
Lin, Y., Sandberg, M., Cehlin, M., Claesson, L. & Wigö, H. (2022). Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements. In: 5th International Conference on Building Energy and Environment (COBEE 2022): . Paper presented at COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022. Springer, Article ID 1419.
Open this publication in new window or tab >>Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements
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2022 (English)In: 5th International Conference on Building Energy and Environment (COBEE 2022), Springer , 2022, article id 1419Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Springer, 2022
Keywords
City ventilation, Compact urban morphology, Wind tunnel experiment, Tracer gas measurement, Single-side ventilation
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39649 (URN)10.1007/978-981-19-9822-5_311 (DOI)2-s2.0-85172730229 (Scopus ID)9789811998218 (ISBN)
Conference
COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022
Funder
Swedish Research Council Formas, 2018-00238
Available from: 2022-08-03 Created: 2022-08-03 Last updated: 2023-11-23Bibliographically approved
Buccolieri, R., Lin, Y., Wigö, H. & Sandberg, M. (2021). Drag force rose representing the interaction between urban geometries and wind. In: 15th ROOMVENT (Roomvent 2020) virtual conference: Energy efficient ventilation for healthy future buildings. Paper presented at 15th Roomvent virtual conference, 15-17 February 2021, Turin, Italy (pp. 85-88).
Open this publication in new window or tab >>Drag force rose representing the interaction between urban geometries and wind
2021 (English)In: 15th ROOMVENT (Roomvent 2020) virtual conference: Energy efficient ventilation for healthy future buildings, 2021, p. 85-88Conference paper, Published paper (Refereed)
Abstract [en]

The drag force generated by aligned arrays of cubes of different packing density and exposed to different wind directions in a wind tunnel is discussed. Results allowed to build a drag force rose which shows that the drag force increases with increasing packing density till λp = 0.25 for any wind direction. It is also shown that, independent of the packing density, the drag force increases with increases deviation of WD from the perpendicularity.

Keywords
Drag force rose, Wind tunnel, Cubic building arrays
National Category
Other Mechanical Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-36559 (URN)9788894612301 (ISBN)
Conference
15th Roomvent virtual conference, 15-17 February 2021, Turin, Italy
Funder
Swedish Research Council Formas, 2018-00238
Available from: 2021-06-27 Created: 2021-06-27 Last updated: 2022-12-29Bibliographically approved
Sandberg, M., Kabanshi, A. & Wigö, H. (2020). Is building ventilation a process of diluting contaminants or delivering clean air?. Indoor + Built Environment, 29(6), 768-774
Open this publication in new window or tab >>Is building ventilation a process of diluting contaminants or delivering clean air?
2020 (English)In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 29, no 6, p. 768-774Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to discuss the performance of air distribution systems intended for dilution of contaminants (e.g. mixing ventilation) and those intended for delivery of clean air to local regions within rooms (e.g. personalized ventilation). We first start by distinguishing the systems by their visiting frequency behaviour. Then, the performance of the systems with respect to their possibility to influence contaminant concentration in the room or regions within the room is dealt with. Dilution capacity concept for mixing systems is discussed, and delivery capacity concept for systems intended to deliver clean air locally is introduced. Various ways for supply of clean air to regions within the room are presented and their pros and cons are discussed. In delivery capacity systems, the most important single parameter is the entrainment of ambient air into the primary supply flow. Therefore, methods of determining entrainment in these systems need to be defined and the results should be included when describing the performance of the air terminal devices.

Place, publisher, year, edition, pages
Sage Publications, 2020
Keywords
Probability to return, Visitation frequency, Dilution capacity, Delivery capacity, Entrainment, Entrainment mixing factor
National Category
Applied Mechanics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-29401 (URN)10.1177/1420326X19837340 (DOI)000547264600002 ()2-s2.0-85063324859 (Scopus ID)
Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2021-02-17Bibliographically approved
Cehlin, M., Ameen, A., Sandberg, M., Claesson, L., Wigö, H. & Lin, Y. (2020). Urban Morphology and City Ventilation. In: : . Paper presented at 10th International Conference on Future Environment and Energy (ICFEE 2020).
Open this publication in new window or tab >>Urban Morphology and City Ventilation
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2020 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The purpose of the paper is to examine the relation between urban morphology, wind direction and air flow rates. In the study a highly idealized city model was used consisting of a circular block divided into two or four equally large sectors. Wind tunnel experiments and CFD predictions have been conducted. The interaction between the atmospheric boundary layer and a city is considered to be both a function of the overall shape and the internal resistance to the flow caused by the friction when the wind flows over the urban surfaces. Flow along the streets is generated by pressure differences. In the wind tunnel, velocity measurements have been recorded in the streets at several points and pressure on the ground was registered in 400 points. The wind tunnel measurements were used to validate the CFD model. The CFD predictions provided complete flow and pressure fields for different configurations and wind directions. The flow balance is presented considering both the horizontal air flow and the vertical air flow (subsidence and updraft). Special attention was on the pressure distribution at ground level (pressure footprint), which is believed to provide valuable information that can be used for qualitative city ventilation analyses. 

Keywords
Urban Morphology, City Ventilation, Crossings
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-40631 (URN)
Conference
10th International Conference on Future Environment and Energy (ICFEE 2020)
Funder
Swedish Research Council Formas, 2018-00238
Available from: 2022-12-26 Created: 2022-12-26 Last updated: 2022-12-29Bibliographically approved
Yang, B., Melikov, A., Kabanshi, A., Zhang, C., Bauman, F. S., Cao, G., . . . Lin, Z. (2019). A review of advanced air distribution methods - theory, practice, limitations and solutions. Energy and Buildings, 202, Article ID 109359.
Open this publication in new window or tab >>A review of advanced air distribution methods - theory, practice, limitations and solutions
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2019 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 202, article id 109359Article in journal (Refereed) Published
Abstract [en]

Ventilation and air distribution methods are important for indoor thermal environments and air quality. Effective distribution of airflow for indoor built environments with the aim of simultaneously offsetting thermal and ventilation loads in an energy efficient manner has been the research focus in the past several decades. Based on airflow characteristics, ventilation methods can be categorized as fully mixed or non-uniform. Non-uniform methods can be further divided into piston, stratified and task zone ventilation. In this paper, the theory, performance, practical applications, limitations and solutions pertaining to ventilation and air distribution methods are critically reviewed. Since many ventilation methods are buoyancy driving that confines their use for heating mode, some methods suitable for heating are discussed. Furthermore, measuring and evaluating methods for ventilation and air distribution are also discussed to give a comprehensive framework of the review.

Keywords
Fully mixing ventilation, Non-uniform ventilation, Air distribution, Thermal comfort, Air quality, Energy efficiency
National Category
Other Engineering and Technologies
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-30538 (URN)10.1016/j.enbuild.2019.109359 (DOI)000503829200053 ()2-s2.0-85070316248 (Scopus ID)
Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2021-03-31Bibliographically approved
Buccolieri, R., Sandberg, M., Wigö, H. & Di Sabatino, S. (2019). The drag force distribution within regular arrays of cubes and its relation to cross ventilation – Theoretical and experimental analyses. Journal of Wind Engineering and Industrial Aerodynamics, 189, 91-103
Open this publication in new window or tab >>The drag force distribution within regular arrays of cubes and its relation to cross ventilation – Theoretical and experimental analyses
2019 (English)In: Journal of Wind Engineering and Industrial Aerodynamics, ISSN 0167-6105, E-ISSN 1872-8197, Vol. 189, p. 91-103Article in journal (Refereed) Published
Abstract [en]

A novel set of wind tunnel measurements of the drag force and its spatial distribution along aligned arrays of cubes of height H and planar area index λ p (air gap between cubes) equal to 0.028 (5H) to 0.69 (0.2H) is presented and analysed. Two different types of measurements are compared: one type where the drag force is obtained using the standard load cell method, another type where the drag force is estimated by measuring the pressure difference between windward and the leeward façades. Results show that the drag force is nearly uniformly distributed for lower λ p (0.028 and 0.0625), it decreases up to 50% at the second row for λ p = 0.11, and it sharply decreases for larger λ p (from 0.25 to 0.69) where the force mostly acts on the first row. It follows that for the lowest λ p the drag force typically formulated as a drag area corresponds to the total frontal area of the array, whereas for large λ p the drag area corresponds to the area of the first row. By assessing the driving pressure for ventilation from the drag force, the analysis is extended to estimate the cross ventilation as an example of application of this type of measurements. 

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Cross ventilation, Cubic building arrays, Drag area, Drag distribution, Interference factor, Standard load cell, Geometry, Ventilation, Wind tunnels, Aligned arrays, Cubic building, Experimental analysis, Pressure differences, Standard loads, Wind tunnel measurements, Drag
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-30516 (URN)10.1016/j.jweia.2019.03.022 (DOI)000467392500008 ()2-s2.0-85064004026 (Scopus ID)
Funder
EU, Horizon 2020, 689954
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2021-02-17Bibliographically approved
Sandberg, M., Wigö, H. & Kabanshi, A. (2018). Is Building Ventilation a Process of Diluting Contaminants or Delivering Clean Air?. In: Risto Kosonen, Mervi Ahola and Jarkko Narvanne (Ed.), Excellent Indoor Climate and High Performing Ventilation: . Paper presented at Roomvent and Ventilation 2018, 2-5 June 2018, Aalto University, Espoo, Finland (pp. 253-258).
Open this publication in new window or tab >>Is Building Ventilation a Process of Diluting Contaminants or Delivering Clean Air?
2018 (English)In: Excellent Indoor Climate and High Performing Ventilation / [ed] Risto Kosonen, Mervi Ahola and Jarkko Narvanne, 2018, p. 253-258Conference paper, Published paper (Refereed)
Abstract [en]

The purpose of the paper is to discuss the performance of air distribution systems intended for dilution of contaminants and those intended for delivery of clean air to local regions within rooms. At first the systems are distinguished by their visiting frequency behaviour. The performance of the systems with respect to their possibility to influence the concentration due to contaminants is dealt with by the concept dilution capacity for mixing systems and by introduction of the concept delivery capacity for systems intended for delivery of clean air locally. Various ways of realizing systems for supply of clean air to regions within a room are presented and their pros and cons are discussed.  The most important single parameter is the entrainment of ambient air into the primary flow that drives the airflow in the room.   

Keywords
probability to return, visitation frequency, dilution capacity, delivery capacity, entrainment, mixing factor due to entrainment
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-26850 (URN)978-952-5236-48-4 (ISBN)
Conference
Roomvent and Ventilation 2018, 2-5 June 2018, Aalto University, Espoo, Finland
Note

Digital, password-protected proceedings

Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2021-02-17Bibliographically approved
Kabanshi, A., Sandberg, M. & Wigö, H. (2018). Measurement of Entrainment into an Axisymmetric Jet using Temperature as a Tracer: A Pilot Study. In: Risto Kosonen, Mervi Ahola and Jarkko Narvanne (Ed.), Excellent Indoor Climate and High Performing Ventilation: . Paper presented at Roomvent and Ventilation 2018, 2-5 June 2018, Aalto University, Espoo,Finland (pp. 397-402).
Open this publication in new window or tab >>Measurement of Entrainment into an Axisymmetric Jet using Temperature as a Tracer: A Pilot Study
2018 (English)In: Excellent Indoor Climate and High Performing Ventilation / [ed] Risto Kosonen, Mervi Ahola and Jarkko Narvanne, 2018, p. 397-402Conference paper, Published paper (Refereed)
Abstract [en]

The current extended abstract is a pilot study of an ongoing experimental and theoretical investigation of ambient entrainment of room air into an axisymmetric free jet using temperature as a tracer. The project aims to investigate, by revisiting the concepts and fundamentals of axisymmetric free Jets and entrainment in ventilation applications, particularly focusing on how to optimize performance of low mixing air distribution systems and to test methods of measuring entrainment in such systems. The study aims to explore a scalar field method using temperature as a tracer to estimate entrainment in axisymmetric free Jets. The results obtained show jet characteristics that slightly differ from what is reported in velocity field measurements and other scalar field studies. Thus, a call is made herein for further investigations to understand entrainment and appropriate methods to determine jet characteristics and its mixing effect. Additionally, more studies are needed to verify whether earlier results are representative of entrainment conditions for low mixing ventilation systems whose operation mode depend on near-filed characteristics of jets.

Keywords
Entrainment, jets, near-field, passive tracer, temperature, delivery capacity
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-26849 (URN)978-952-5236-48-4 (ISBN)
Conference
Roomvent and Ventilation 2018, 2-5 June 2018, Aalto University, Espoo,Finland
Note

Digital, password-protected proceedings

Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2021-02-17Bibliographically approved
Antoniou, N., Montazeri, H., Wigö, H., Neophytou, M., Blocken, B. & Sandberg, M. (2017). CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area: evaluation using “air delay”. Building and Environment, 126, 355-372
Open this publication in new window or tab >>CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area: evaluation using “air delay”
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2017 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 126, p. 355-372Article in journal (Refereed) Published
Abstract [en]

Outdoor urban ventilation in a real complex urban area is investigated by introducing a new ventilation indicator – the "air delay". Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The up-to-date literature shows the lack of detailed evaluations of the two approaches for real compact urban areas. This study further presents a systematic evaluation of steady RANS and LES for the assessment of the ventilation conditions in a dense district in Nicosia, Cyprus. The ventilation conditions within the urban area are investigated by calculating the distribution of the age of air. To better assess the outdoor ventilation, a new indicator, the "air delay" is introduced as the difference between the local mean age of air at an urban area and that in an empty domain with the same computational settings, allowing the comparison of the results in different parts of the domain, without impact of the boundary conditions. CFD results are validated using wind-tunnel measurements of mean wind speed and turbulence intensity performed for the same urban area. The results show that LES can accurately predict the mean wind speed and turbulence intensity with the average deviations of about 6% and 14%, respectively, from the wind-tunnel measurements while for the steady RANS, these are 8% and 31%, respectively. The steady RANS simulations overestimate the local mean air delay. The deviation between the two approaches is 52% at pedestrian level (2 m).

Keywords
Air delay, City breathability, Computational Fluid Dynamics (CFD), Large Eddy Simulations (LES), Steady RANS, Urban microclimate
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-25585 (URN)10.1016/j.buildenv.2017.10.013 (DOI)000417010000030 ()2-s2.0-85042085549 (Scopus ID)
Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2021-02-17Bibliographically approved
Buccolieri, R., Wigö, H., Sandberg, M. & Di Sabatino, S. (2017). Direct measurements of the drag force over aligned arrays of cubes exposed to boundary-layer flows. Environmental Fluid Mechanics, 17(2), 373-394
Open this publication in new window or tab >>Direct measurements of the drag force over aligned arrays of cubes exposed to boundary-layer flows
2017 (English)In: Environmental Fluid Mechanics, ISSN 1567-7419, E-ISSN 1573-1510, Vol. 17, no 2, p. 373-394Article in journal (Refereed) Published
Abstract [en]

Wind tunnel measurements of the total drag force for aligned arrays of cubes exposed to two different boundary-layer flows at three flow velocities are discussed. The drag force for eight different building packing densities λp (from 0.028 to 1) is measured with a standard load cell generating a novel dataset. Different λp are reproduced by increasing the number of buildings on the same lot area; this represents a real situation that an urban planner is faced with when a lot area of a given (fixed) size is allocated to the development of new built areas. It is assumed that the surrounding terrain is uniform and there is a transition from a given roughness (smooth) to a new roughness (rough). The approaching flow will adjust itself over the new surface within a distance that in general may be larger than the horizontal length covered by the array. We investigate the region where the flow adjustment occurs. The wide range of packing densities allowed us to analyse in detail the evolution of the drag force. The drag force increases with increasing packing densities until it reaches a maximum at an intermediate packing density (λp = 0.25 in our case) followed by a slight decrease at larger packing densities. The value of the drag force depends on the flow adjustment along the array which is evaluated by introducing the parameter “drag area” to retrieve information about the drag distribution at different λp. Results clearly suggest a change of the distribution of the drag force, which is found to be relatively uniform at low packing densities, while most of the force acts on first rows of the arrays at large packing densities. The drag area constitutes the basis for the formulation of a new adjustment length scale defined as the ratio between the volume of the air within the array and the drag area. The proposed adjustment length scale automatically takes into account the change in drag distribution along the array for a better parameterization of urban effects in dispersion models. 

Keywords
Adjustment length scale, Cubic building arrays, Drag area, Drag force, Planar area index, Standard load cell
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-22978 (URN)10.1007/s10652-016-9493-9 (DOI)000410853200009 ()2-s2.0-84996587562 (Scopus ID)
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2021-02-17Bibliographically approved
Projects
A new ventilation technique based on velocity variation as a method to improve thermal comfort and ventilation efficiency [2008-64_Formas]; University of GävleStadsventilation [2018-00238_Formas]; University of Gävle; Publications
Cehlin, M., Lin, Y., Sandberg, M., Claesson, L. & Wallhagen, M. (2023). Towards benchmarking of urban air quality based on homogenous surface emission. Results in Engineering (RINENG), 20, Article ID 101617. Lin, Y., Sandberg, M., Cehlin, M., Claesson, L. & Wigö, H. (2022). Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements. In: 5th International Conference on Building Energy and Environment (COBEE 2022): . Paper presented at COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022. Springer, Article ID 1419. Buccolieri, R., Lin, Y., Wigö, H. & Sandberg, M. (2021). Drag force rose representing the interaction between urban geometries and wind. In: 15th ROOMVENT (Roomvent 2020) virtual conference: Energy efficient ventilation for healthy future buildings. Paper presented at 15th Roomvent virtual conference, 15-17 February 2021, Turin, Italy (pp. 85-88). Cehlin, M., Ameen, A., Sandberg, M., Claesson, L., Wigö, H. & Lin, Y. (2020). Urban Morphology and City Ventilation. In: : . Paper presented at 10th International Conference on Future Environment and Energy (ICFEE 2020).
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