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Diogo B. Pitz

Bio: Diogo B. Pitz is an academic researcher from Federal University of Paraná. The author has contributed to research in topics: Rayleigh number & Buoyancy. The author has an hindex of 6, co-authored 12 publications receiving 82 citations. Previous affiliations of Diogo B. Pitz include Federal University of Technology - Paraná & University of Surrey.

Papers
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TL;DR: In this article, the authors analyzed the onset of buoyancy in a rotating cylindrical cavity bounded by two plane insulated disks, adopting a geometrical configuration relevant to fundamental studies of buoyant-induced flows occurring in gas turbine's internal air systems.
Abstract: Flows induced by centrifugal buoyancy occur in rotating systems in which the centrifugal force is large when compared to other body forces and are of interest for geophysicists and also in engineering problems involving rapid rotation and unstable temperature gradients. In this numerical study we analyse the onset of centrifugal buoyancy in a rotating cylindrical cavity bounded by two plane, insulated disks, adopting a geometrical configuration relevant to fundamental studies of buoyancy-induced flows occurring in gas turbine’s internal air systems. Using linear stability analysis, we obtain critical values of the centrifugal Rayleigh number and corresponding critical azimuthal wavenumbers for the onset of convection for different radius ratios. Using direct numerical simulation, we integrate the solutions starting from a motionless state to which small sinusoidal perturbations are added, and show that nonlinear triadic interactions occur before energy saturation takes place. At the lowest Rayleigh number considered, the final state is a limit-cycle oscillation affected by the presence of the disks, having a spectrum dominated by a certain mode and its harmonics. We show that, for this case, the limit-cycle oscillations only develop when no-slip end walls are present. For the largest considered chaotic motion occurs, but the critical wavenumber obtained from the linear analysis eventually becomes the most energetic even in the turbulent regime.

22 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented buoyancy-induced flow for a sealed rotating cavity with rotational inertia in the range 10 − to 10 − 1 for an incompressible model with Boussinesq approximation, compared with a compressible gas flow model.

17 citations

Journal ArticleDOI
TL;DR: In this paper, large-eddy simulation is used to study buoyancy-induced flow in a rotating cavity with an axial throughflow of cooling air, where the thickness of boundary layers forming near the upstream and downstream disks is consistent with that of a laminar Ekman layer, although the boundary layer thickness distribution along the radial direction presents greater variations than in the sealed cavity case.

16 citations

Journal ArticleDOI
TL;DR: In this paper, an assessment of physics-based and data-driven reduced-order models for convective heat transfer in a rectangular cavity is presented for the study of convective energy transfer.
Abstract: An assessment of physics-based and data-driven reduced-order models (ROMs) is presented for the study of convective heat transfer in a rectangular cavity. Despite the simple geometrical con...

16 citations


Cited by
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Journal ArticleDOI
Jing Gao1, Yun-Ren Qiu1, Ben Hou, Qiang Zhang1, Xiaodong Zhang1 
TL;DR: In this paper, a rotating disk membrane module was used to recover nickel from wastewater containing nickel by complexation-ultrafiltration using sodium polyacrylate (PAAS) as complexation agent.

53 citations

Journal ArticleDOI
TL;DR: This work presents a novel approach to boost the Rayleigh number in thermal convection by exploiting centrifugal acceleration and rapidly rotating a cylindrical annulus to reach an effective gravity of 60 times Earth’s gravity.
Abstract: High-Rayleigh number convective turbulence is ubiquitous in many natural phenomena and in industries, such as atmospheric circulations, oceanic flows, flows in the fluid core of planets, and energy generations. In this work, we present a novel approach to boost the Rayleigh number in thermal convection by exploiting centrifugal acceleration and rapidly rotating a cylindrical annulus to reach an effective gravity of 60 times Earth's gravity. We show that in the regime where the Coriolis effect is strong, the scaling exponent of Nusselt number versus Rayleigh number exceeds one-third once the Rayleigh number is large enough. The convective rolls revolve in prograde direction, signifying the emergence of zonal flow. The present findings open a new avenue on the exploration of high-Rayleigh number turbulent thermal convection and will improve the understanding of the flow dynamics and heat transfer processes in geophysical and astrophysical flows and other strongly rotating systems.

27 citations

Journal ArticleDOI
16 Apr 2019
TL;DR: In this article, it was shown that thermal convection due to centrifugal buoyancy in a cylindrical annulus occurs in the form of drifting columnar vortices.
Abstract: An investigation shows that thermal convection due to centrifugal buoyancy in a cylindrical annulus occurs in the form of drifting columnar vortices. For Rayleigh number $R\phantom{\rule{0}{0ex}}a$ g 105, the Coriolis buoyancy deforms the columns and thermal plumes.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of aspect ratio (0.1≤AR≤0.7), Rayleigh number (102≤Ra≤106), and inclination angle 0° ǫ ≥ γ 0.90° of the heated rectangular cylinder on heat transfer and fluid flow chara
Abstract: This paper presents the effects of aspect ratio (0.1≤AR≤0.7), Rayleigh number (102≤Ra≤106) and inclination angle 0° ≤γ ≤ 90° of the heated rectangular cylinder on heat transfer and fluid flow chara...

22 citations

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the onset of buoyancy in a rotating cylindrical cavity bounded by two plane insulated disks, adopting a geometrical configuration relevant to fundamental studies of buoyant-induced flows occurring in gas turbine's internal air systems.
Abstract: Flows induced by centrifugal buoyancy occur in rotating systems in which the centrifugal force is large when compared to other body forces and are of interest for geophysicists and also in engineering problems involving rapid rotation and unstable temperature gradients. In this numerical study we analyse the onset of centrifugal buoyancy in a rotating cylindrical cavity bounded by two plane, insulated disks, adopting a geometrical configuration relevant to fundamental studies of buoyancy-induced flows occurring in gas turbine’s internal air systems. Using linear stability analysis, we obtain critical values of the centrifugal Rayleigh number and corresponding critical azimuthal wavenumbers for the onset of convection for different radius ratios. Using direct numerical simulation, we integrate the solutions starting from a motionless state to which small sinusoidal perturbations are added, and show that nonlinear triadic interactions occur before energy saturation takes place. At the lowest Rayleigh number considered, the final state is a limit-cycle oscillation affected by the presence of the disks, having a spectrum dominated by a certain mode and its harmonics. We show that, for this case, the limit-cycle oscillations only develop when no-slip end walls are present. For the largest considered chaotic motion occurs, but the critical wavenumber obtained from the linear analysis eventually becomes the most energetic even in the turbulent regime.

22 citations