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Airflow Pattern

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Klaus Sedlbauer – One of the best experts on this subject based on the ideXlab platform.

  • vepzo velocity propagating zonal model for the estimation of the Airflow Pattern and temperature distribution in a confined space
    Building and Environment, 2012
    Co-Authors: Victor Norrefeldt, Gunnar Grun, Klaus Sedlbauer

    Abstract:

    Abstract The goal of this paper is to build a locally refined non-isothermal Airflow model. This model should not need prior knowledge of the expected Airflow Pattern to allow the evaluation of many different configurations. For this a new zonal model, the VEPZO (VElocity Propagating ZOnal) model has been developed including the Airflow velocity as a property of a zone and a viscous loss model to compute the Airflow between the zones. The velocity information from a zone is passed to the flow models and is therefore propagated into the room. Instead of using the power law equation or specialized jet or plume correlations to model the Airflow between two zones, an equation derived from the forces acting on a flow path is used. These forces generate an acceleration or deceleration of the Airflow. Losses are modelled by viscous dissipation. Two other models, the singular loss and the buoyant singular loss model are presented too. These models can be used to model flow paths through e.g. windows or doors. Results using the VEPZO model are compared with data from two case studies used to validate other zonal models. Airflow and temperature distributions are comparable to the results calculated by other zonal models. Furthermore, the VEPZO model is compared to an experimental setup with several interacting heat sources, showing the strength of the approach not needing specialized correlations for these elements. The VEPZO model is implemented in the equation-based and object-oriented language Modelica and can therefore be interfaced to other physical models.

Victor Norrefeldt – One of the best experts on this subject based on the ideXlab platform.

  • vepzo velocity propagating zonal model for the prediction of Airflow Pattern and temperature distribution in enclosed spaces
    International Modelica Conference, 2012
    Co-Authors: Victor Norrefeldt, Gunnar Grun

    Abstract:

    This paper presents the VEPZO-model (VElocity Propagating ZOnal model), the first three dimensional Airflow model for indoor spaces that has been implemented in Modelica. The model predicts Airflow and temperature distribution in a room. The main feature of the VEPZO model is that each zone has a characteristic velocity depending on entering and leaving Airflows. This characteristic velocity is propagated into space ensuring the propagation of driving Airflows. The VEPZO model can be interfaced to other models of the Modelica.Standard library. In an application example a displacement ventilation in a twin-aisle aircraft cabin is investigated. The temperature in the occupied zones is predicted between 20.6 and 23.0 °C.

  • vepzo velocity propagating zonal model for the estimation of the Airflow Pattern and temperature distribution in a confined space
    Building and Environment, 2012
    Co-Authors: Victor Norrefeldt, Gunnar Grun, Klaus Sedlbauer

    Abstract:

    Abstract The goal of this paper is to build a locally refined non-isothermal Airflow model. This model should not need prior knowledge of the expected Airflow Pattern to allow the evaluation of many different configurations. For this a new zonal model, the VEPZO (VElocity Propagating ZOnal) model has been developed including the Airflow velocity as a property of a zone and a viscous loss model to compute the Airflow between the zones. The velocity information from a zone is passed to the flow models and is therefore propagated into the room. Instead of using the power law equation or specialized jet or plume correlations to model the Airflow between two zones, an equation derived from the forces acting on a flow path is used. These forces generate an acceleration or deceleration of the Airflow. Losses are modelled by viscous dissipation. Two other models, the singular loss and the buoyant singular loss model are presented too. These models can be used to model flow paths through e.g. windows or doors. Results using the VEPZO model are compared with data from two case studies used to validate other zonal models. Airflow and temperature distributions are comparable to the results calculated by other zonal models. Furthermore, the VEPZO model is compared to an experimental setup with several interacting heat sources, showing the strength of the approach not needing specialized correlations for these elements. The VEPZO model is implemented in the equation-based and object-oriented language Modelica and can therefore be interfaced to other physical models.

Hongtao Wang – One of the best experts on this subject based on the ideXlab platform.

  • a wind tunnel simulation of the effects of stoss slope on the lee Airflow Pattern over a two dimensional transverse dune
    Journal of Geophysical Research, 2007
    Co-Authors: Zhibao Dong, Guangqiang Qian, Wanyin Luo, Hongtao Wang

    Abstract:

    [1] Secondary Airflow plays an important role in dune formation and development. The lee Airflow Pattern over transverse dunes is important in determining the shape, alignment, and spacing of dunes and is influenced significantly by the lee slope angle. In this paper we present the results of scaled wind tunnel simulations of the effects of stoss slope on the mean lee Airflow Patterns of transverse dunes. The leeward velocity field was measured nonintrusively using particle image velocimetry to assess the Airflow Pattern. We found that the flow separated over the dunes with a leeward angle close to the slip face angle of natural transverse dunes and was insensitive to stoss angle. Separation cells were characterized by a back eddy. Reattachment distance, height, area, and aspect ratio were used to characterize the separation cell. The first three parameters increased with increasing stoss angle for angles less than 15° but remained constant or decreased slightly with angles greater than 15°. On the basis of the leeward velocity profiles, six flow regions corresponding to those in previous models were recognized. These regions are initially bounded by kinks but gradually transition downwind and merge to recover a uniform velocity profile after a significant distance. We suggest that the separation cell is most developed when the angle of stoss slope reaches 15°, but the significance of this angle in the evolution of transverse dunes needs further exploration.

  • A wind tunnel simulation of the effects of stoss slope on the lee Airflow Pattern over a two‐dimensional transverse dune
    Journal of Geophysical Research, 2007
    Co-Authors: Zhibao Dong, Guangqiang Qian, Wanyin Luo, Hongtao Wang

    Abstract:

    [1] Secondary Airflow plays an important role in dune formation and development. The lee Airflow Pattern over transverse dunes is important in determining the shape, alignment, and spacing of dunes and is influenced significantly by the lee slope angle. In this paper we present the results of scaled wind tunnel simulations of the effects of stoss slope on the mean lee Airflow Patterns of transverse dunes. The leeward velocity field was measured nonintrusively using particle image velocimetry to assess the Airflow Pattern. We found that the flow separated over the dunes with a leeward angle close to the slip face angle of natural transverse dunes and was insensitive to stoss angle. Separation cells were characterized by a back eddy. Reattachment distance, height, area, and aspect ratio were used to characterize the separation cell. The first three parameters increased with increasing stoss angle for angles less than 15° but remained constant or decreased slightly with angles greater than 15°. On the basis of the leeward velocity profiles, six flow regions corresponding to those in previous models were recognized. These regions are initially bounded by kinks but gradually transition downwind and merge to recover a uniform velocity profile after a significant distance. We suggest that the separation cell is most developed when the angle of stoss slope reaches 15°, but the significance of this angle in the evolution of transverse dunes needs further exploration.