Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session J32: Turbulent Convection |
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Chair: Yue Hao, Johns Hopkins University Room: 255 D |
Sunday, November 24, 2024 5:50PM - 6:03PM |
J32.00001: Assessment of turbulence models for evaporation and stratification in cryogenic storage tanks Johan R Espelund, Magnus A Gjennestad, Sindre S Blakseth, Corinna Netzer According to the International Energy Agency, the use of renewable energy sources |
Sunday, November 24, 2024 6:03PM - 6:16PM |
J32.00002: Measuring turbulence intensity and length scale using low-cost cylindrical sensors for quantifying human convective heat transfer in outdoor flows Emily Parkerson, Mahima Gupta, Ankit Joshi, Shri H Viswanathan, Gokul Pathikonda, Konrad Rykaczewski Developing accurate yet affordable sensors for measuring human radiative and convective exposure in extremely hot conditions can inform behavioral, policy, and infrastructure decisions around heat. While there are many such radiation sensors, quantification of convective heat transfer from the human body in outdoor flows, which are highly turbulent, requires expensive 3D anemometers and advanced data processing. Specifically, besides mean wind speed, turbulence intensity (TI), and turbulence length scale (Lt) substantially impact the forced convection heat transfer coefficient from the human body [1]. Here, we explore an alternative approach based on three heated isothermal cylinders with the same optical properties but varied diameters [2]. By accounting for thermal radiation using another set of cylinders with varied properties but the same diameter [2], the mean wind speed, TI, and Lt are the only unknowns in energy balances on the three varied diameter cylinders. We discuss the performance of the cylinders in measuring the three airflow parameters in grid-generated turbulent flow in a wind tunnel and in highly non-stationary outdoor flow. |
Sunday, November 24, 2024 6:16PM - 6:29PM |
J32.00003: Forced convection from the human body in turbulent outdoor flows Ankit Joshi, Shri H Viswanathan, Ankush K Jaiswal, Kambiz Sadeghi, Lyle Bartels, Gokul Pathikonda, Konrad Rykaczewski Forced convective heat exchange with the human body has been either simulated or measured in wind tunnels using thermal manikins, but predictions from the resulting 10+ correlations vary greatly. Recent research has highlighted that such disparities are likely caused by not taking all relevant turbulent flow parameters (i.e., turbulence intensity (TI) and length scale (Lt)). The Lt range common in outdoor flows at pedestrian level (1-15 m) is complicated to replicate in a wind tunnel. We describe an alternative method using a one-of-a-kind outdoor thermal manikin, ANDI, to measure convective heat transfer in outdoor conditions [1]. Using these results, we validate a new geometry-rooted model that demonstrates that different body parts and the whole body are well-approximated by cylinders, even in turbulent flow. |
Sunday, November 24, 2024 6:29PM - 6:42PM |
J32.00004: Kinetic energy dissipation rate field in the bulk of fully compressible convection Shadab Alam, John Panickacheril John, Roshan J Samuel, Jörg Schumacher We investigate the local statistics of the kinetic energy dissipation rate and its solenoidal, dilatational, and inhomogeneous components in the bulk of fully compressible convection (FCC). We employ direct numerical simulations in a fluid layer of aspect ratio Γ = 4 for fixed Prandtl number Pr = 0.7, superadiabaticity ε = 0.45 and dissipation number D = 0.5. The Rayleigh number Ra varies from 105 to 107. We observe that probability distribution functions (pdfs) are close to those in homogeneous isotropic turbulence: the left tails of the total and solenoidal dissipation rate fields follow 3/2 and 1/2 power laws, respectively, while the right tails follow a stretched exponential. The pdfs also show that FCC is markedly more intermittent than Boussinesq convection, a finding that is further reinforced by our multifractal analysis. Moreover, using the statistical and multifractal properties of the three parts of the dissipation rate field and their relative magnitude, we study their contribution to turbulent mixing in the bulk of the turbulent convection layer. |
Sunday, November 24, 2024 6:42PM - 6:55PM |
J32.00005: Abstract Withdrawn |
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