Large-scale flow structures and heat transport of turbulent forced and mixed convection in a closed rectangular cavity

Schmeling, Daniel; Westhoff, Andreas; Kühn, Matthias; Bosbach, Johannes; Wagner, Claus

doi:10.1016/j.ijheatfluidflow.2011.06.006

Cited by 23 publications

(12 citation statements)

References 22 publications

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“…The core line positions obtained, presented in Fig. 5 (top), reveal a wave-like shape with a wavelength of approximately 0.5 m. This observation is in a very good agreement with the results of Schmeling et al (2011) and Westhoff et al (2010), who analysed stereoscopic PIV data of forced convection in the same apparatus at a similar Re. We suspect that the wavy shape is a result of the interaction of the flow with the side walls in cell's X-direction, and thus reflects the longitudinal aspect ratio of the apparatus.…”

Section: Forced Convectionsupporting

confidence: 88%

“…11 top). They were already detected by Schmeling et al (2011) in the same apparatus for a similar Archimedes number by analysing temperature measurements in the air Fig. 11 Sketch of expected orientation of counter-rotating convection rolls in X-Y (top) and X-Z (bottom) planes (bullet corresponds to the hot, rising fluid and 9 to falling fluid in the right sketch).…”

Section: Mixed Convectionmentioning

confidence: 80%

“…However, the observed large-scale flow structures were time dependent and three-dimensional. For mixed convection, a break-up of the twodimensional roll structure into four large-scale convection rolls was observed in experimental studies using planar PIV (Schmeling et al , 2011. Direct numerical simulations of Rayleigh-Bénard convection in the same configuration revealed a similar arrangement of up to four convection rolls (Kaczorowski and Wagner 2009).…”

Section: Introductionmentioning

confidence: 86%

“…Optical access to the flow inside the cell is provided by the front and side walls, which are made of 10 mm thick polycarbonate plates. For a detailed description of the apparatus, the reader is referred to Kühn et al (2011) and Schmeling et al ( , 2011. For the quantitative measurement of the large-scale flow structures, a specially built tomographic PIV system (see Kühn et al 2011) was applied to the cell, which covered a measurement volume as large as 840 mm 9 500 mm 9 240 mm.…”

Section: Convection Cell and Tomographic Piv Set-upmentioning

confidence: 99%

“…To study forced and mixed convection in a well-defined environment, a convection cell with a length of 2.5 m and a quadratic cross-section of 0.5 m90.5 m was developed (see Kühn et al 2011;Schmeling et al , 2011. In a previous investigation of forced convection employing large-scale tomographic PIV in this configuration, the mean velocity field revealed a nearly two-dimensional rolllike structure with a homogeneous wavy shape of the core line .…”

Section: Introductionmentioning

confidence: 99%

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Large-scale tomographic PIV in forced and mixed convection using a parallel SMART version

et al. 2012

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Large-scale tomographic particle image velocimetry (tomographic PIV) was used to study large-scale flow structures of turbulent convective air flow in an elongated rectangular convection cell. Three flow cases have been investigated, that is, pure forced convection and mixed convection at two different Archimedes numbers. The Reynolds number was constant at Re = 1.04 9 10 4 for all cases, while the Archimedes numbers were Ar = 2.1 and 3.6 for the mixed convection cases, corresponding to Rayleigh numbers of Ra = 1.6 9 10 8 and 2.8 9 10 8 , respectively. In these investigations, the size of the measurement volume was as large as 840 mm 9 500 mm 9 240 mm. To allow for statistical analysis of the measured instantaneous flow fields, a large number of samples needed to be evaluated. Therefore, an efficient parallel implementation of the tomographic PIV algorithm was developed, which is based on a version of the simultaneous multiplicative reconstruction technique (SMART). Our algorithm distinguishes itself amongst other features by the fact that it does not store any weighting coefficients. The measurement of forced convection reveals an almost two-dimensional roll structure, which is orientated in the longitudinal cell direction. Its mean velocity field exhibits a core line with a wavy shape and a wavelength, which corresponds to the height and depth of the cell. In the instantaneous fields, the core line oscillates around its mean position. Under the influence of thermal buoyancy forces, the global structure of the flow field changes significantly. At lower Archimedes numbers, the resulting roll-like structure is shifted and deformed as compared to pure forced convection. Additionally, the core line oscillates much more strongly around its mean position due to the interaction of the roll structure with the rising hot air. If the Archimedes number is further increased, the roll-like structure breaks up into four counter-rotating convection rolls as a result of the increased influence of buoyancy forces. Moreover, large-scale tomographic PIV reveals that the orientation of these rolls reflects a 'W'-like shape in the horizontal X-Z-plane of the convection cell.

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Section: Forced Convectionsupporting

confidence: 88%

Section: Mixed Convectionmentioning

confidence: 80%