On the use of non-conformal grids for economic LES of wind flow and convective heat transfer for a wall-mounted cube

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Generating economical, high-resolution and high-quality computational grids for Large Eddy Simulation (LES) of wind flow and convective heat transfer (CHT) around surface-mounted obstacles is not straightforward. When the grid size is used as filter, LES grids should ideally consist of cubic cells, while CHT requires a very high near-wall resolution to resolve the thin viscous sublayer and buffer layer that represent the largest resistance to CHT. To avoid very high cell numbers and the need for excessive computational resources, non-conformal grids can be considered. This paper provides a detailed evaluation of the performance of non-conformal grids with cubic cells, for wind flow and CHT around a wall-mounted cubic obstacle. LES results on non-conformal versus conformal grids are compared with each other and with wind-tunnel measurements of wind speed and surface temperature. Moreover, sensitivity analysis is performed concerning the impact of overall grid resolution, subdomain size and grid refinement ratio. Average absolute deviations between LES on non-conformal versus conformal grids are about 0.9% (0.5 °C) for surface temperature on all cube surfaces. Comparison with experiments shows for the non-conformal grid an average and maximum absolute deviation for surface temperature of 2.0% (1.1 °C) and 7.6% (3.6 °C), respectively. The sensitivity analysis shows minor impact of subdomain size on convective heat transfer coefficients (CHTC) where, on average, absolute deviations of less than 2.2% are observed. This study shows that non-conformal grids can strongly reduce the total cell count (here by a factor up to 30.2) without significantly compromising the accuracy of results.

TaalEngels
Pagina's44-61
Aantal pagina's18
TijdschriftBuilding and Environment
Volume119
DOI's
StatusGepubliceerd - 1 jul 2017

Vingerafdruk

large eddy simulation
Large eddy simulation
heat
heat transfer
Heat transfer
Economics
simulation
economics
surface temperature
Sensitivity analysis
sensitivity analysis
Buffer layers
wind tunnel
Temperature
Heat transfer coefficients
Wind tunnels
wind velocity
filter
experiment
resource

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    title = "On the use of non-conformal grids for economic LES of wind flow and convective heat transfer for a wall-mounted cube",
    abstract = "Generating economical, high-resolution and high-quality computational grids for Large Eddy Simulation (LES) of wind flow and convective heat transfer (CHT) around surface-mounted obstacles is not straightforward. When the grid size is used as filter, LES grids should ideally consist of cubic cells, while CHT requires a very high near-wall resolution to resolve the thin viscous sublayer and buffer layer that represent the largest resistance to CHT. To avoid very high cell numbers and the need for excessive computational resources, non-conformal grids can be considered. This paper provides a detailed evaluation of the performance of non-conformal grids with cubic cells, for wind flow and CHT around a wall-mounted cubic obstacle. LES results on non-conformal versus conformal grids are compared with each other and with wind-tunnel measurements of wind speed and surface temperature. Moreover, sensitivity analysis is performed concerning the impact of overall grid resolution, subdomain size and grid refinement ratio. Average absolute deviations between LES on non-conformal versus conformal grids are about 0.9{\%} (0.5 °C) for surface temperature on all cube surfaces. Comparison with experiments shows for the non-conformal grid an average and maximum absolute deviation for surface temperature of 2.0{\%} (1.1 °C) and 7.6{\%} (3.6 °C), respectively. The sensitivity analysis shows minor impact of subdomain size on convective heat transfer coefficients (CHTC) where, on average, absolute deviations of less than 2.2{\%} are observed. This study shows that non-conformal grids can strongly reduce the total cell count (here by a factor up to 30.2) without significantly compromising the accuracy of results.",
    keywords = "Conjugate heat transfer, Convective heat transfer coefficients, LES, Non-conformal grids, Sensitivity analysis",
    author = "S. Iousef and H. Montazeri and B. Blocken and {van Wesemael}, {P. J.V.}",
    year = "2017",
    month = "7",
    day = "1",
    doi = "10.1016/j.buildenv.2017.04.004",
    language = "English",
    volume = "119",
    pages = "44--61",
    journal = "Building and Environment",
    issn = "0360-1323",
    publisher = "Elsevier",

    }

    On the use of non-conformal grids for economic LES of wind flow and convective heat transfer for a wall-mounted cube. / Iousef, S.; Montazeri, H.; Blocken, B.; van Wesemael, P. J.V.

    In: Building and Environment, Vol. 119, 01.07.2017, blz. 44-61.

    Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

    TY - JOUR

    T1 - On the use of non-conformal grids for economic LES of wind flow and convective heat transfer for a wall-mounted cube

    AU - Iousef,S.

    AU - Montazeri,H.

    AU - Blocken,B.

    AU - van Wesemael,P. J.V.

    PY - 2017/7/1

    Y1 - 2017/7/1

    N2 - Generating economical, high-resolution and high-quality computational grids for Large Eddy Simulation (LES) of wind flow and convective heat transfer (CHT) around surface-mounted obstacles is not straightforward. When the grid size is used as filter, LES grids should ideally consist of cubic cells, while CHT requires a very high near-wall resolution to resolve the thin viscous sublayer and buffer layer that represent the largest resistance to CHT. To avoid very high cell numbers and the need for excessive computational resources, non-conformal grids can be considered. This paper provides a detailed evaluation of the performance of non-conformal grids with cubic cells, for wind flow and CHT around a wall-mounted cubic obstacle. LES results on non-conformal versus conformal grids are compared with each other and with wind-tunnel measurements of wind speed and surface temperature. Moreover, sensitivity analysis is performed concerning the impact of overall grid resolution, subdomain size and grid refinement ratio. Average absolute deviations between LES on non-conformal versus conformal grids are about 0.9% (0.5 °C) for surface temperature on all cube surfaces. Comparison with experiments shows for the non-conformal grid an average and maximum absolute deviation for surface temperature of 2.0% (1.1 °C) and 7.6% (3.6 °C), respectively. The sensitivity analysis shows minor impact of subdomain size on convective heat transfer coefficients (CHTC) where, on average, absolute deviations of less than 2.2% are observed. This study shows that non-conformal grids can strongly reduce the total cell count (here by a factor up to 30.2) without significantly compromising the accuracy of results.

    AB - Generating economical, high-resolution and high-quality computational grids for Large Eddy Simulation (LES) of wind flow and convective heat transfer (CHT) around surface-mounted obstacles is not straightforward. When the grid size is used as filter, LES grids should ideally consist of cubic cells, while CHT requires a very high near-wall resolution to resolve the thin viscous sublayer and buffer layer that represent the largest resistance to CHT. To avoid very high cell numbers and the need for excessive computational resources, non-conformal grids can be considered. This paper provides a detailed evaluation of the performance of non-conformal grids with cubic cells, for wind flow and CHT around a wall-mounted cubic obstacle. LES results on non-conformal versus conformal grids are compared with each other and with wind-tunnel measurements of wind speed and surface temperature. Moreover, sensitivity analysis is performed concerning the impact of overall grid resolution, subdomain size and grid refinement ratio. Average absolute deviations between LES on non-conformal versus conformal grids are about 0.9% (0.5 °C) for surface temperature on all cube surfaces. Comparison with experiments shows for the non-conformal grid an average and maximum absolute deviation for surface temperature of 2.0% (1.1 °C) and 7.6% (3.6 °C), respectively. The sensitivity analysis shows minor impact of subdomain size on convective heat transfer coefficients (CHTC) where, on average, absolute deviations of less than 2.2% are observed. This study shows that non-conformal grids can strongly reduce the total cell count (here by a factor up to 30.2) without significantly compromising the accuracy of results.

    KW - Conjugate heat transfer

    KW - Convective heat transfer coefficients

    KW - LES

    KW - Non-conformal grids

    KW - Sensitivity analysis

    U2 - 10.1016/j.buildenv.2017.04.004

    DO - 10.1016/j.buildenv.2017.04.004

    M3 - Article

    VL - 119

    SP - 44

    EP - 61

    JO - Building and Environment

    T2 - Building and Environment

    JF - Building and Environment

    SN - 0360-1323

    ER -