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Autor Uhlmann, Markus |
Documentos disponibles escritos por este autor (21)
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Sekimoto, Atshushi ; Sekiyama, K. ; Kawahara, Genta ; Uhlmann, Markus ; Pinelli, Alfredo | Begell House | 2009Direct numerical simulations of fully developed low-Reynolds-number turbulent flow in a horizontal square duct heated from below are performed at Richardson numbers 0 ? Ri ? 1.03 to investigate the buoyancy effects on the coherent structures nea[...]texto impreso
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Direct numerical simulation of fully developed turbulent flow in a straight square duct was performed in order to determine the minimal requirements for self-sustaining turbulence. It was found that turbulence can be maintained for values of the[...]texto impreso
We have conducted a DNS study of dilute turbulent particulate flow in a vertical plane channel, considering up to 8192 finite-size rigid particles with numerically resolved phase interfaces. The particle diameter corresponds to approximately 9 w[...]texto impreso
Kawahara, Genta ; Jiménez, J. ; Uhlmann, Markus ; Pinelli, Alfredo | 2003The linear inviscid instability of an infinitely thin vortex sheet, periodically corrugated with finite amplitude along the spanwise direction, is investigated analytically. Two types of corrugations are studied, one of which includes the presen[...]texto impreso
Kawahara, Genta ; Jiménez, Javier ; Uhlmann, Markus ; Pinelli, Alfredo | Cambridge University Press | 2003The linear inviscid instability of an infinitely thin vortex sheet, periodically corrugated with finite amplitude along the spanwise direction, is investigated analytically. Two types of corrugations are studied, one of which includes the presen[...]texto impreso
Uhlmann, Markus ; Pinelli, Alfredo ; Kawahara, Genta ; Sekimoto, Atshushi | Cambridge University Press | 2007A direct numerical simulation of turbulent flow in a straight square duct was performed in order to determine the minimal requirements for self-sustaining turbulence. It was found that turbulence can be maintained for values of the bulk Reynold[...]texto impreso
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Pinelli, Alfredo ; Uhlmann, Markus ; Sekimoto, Atshushi ; Kawahara, Genta | Cambridge University Press | 2010We have performed direct numerical simulations of turbulent flows in a square duct considering a range of Reynolds numbers spanning from a marginal state up to fully developed turbulent states at low Reynolds numbers. The main motivation stems f[...]texto impreso
The appearance of secondary flow of Prandtl’s second kind is a well-known phenomenon in fully developed turbulent rectangular duct flow. The intensity of the secondary flow is two orders of magnitude smaller than that of the mean streamwise velo[...]texto impreso
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Kawahara, Genta ; Jiménez, J. ; Uhlmann, Markus ; Pinelli, Alfredo | Japan Society of Mechanical Engineers | 2000The linear stability analysis has been performed at Re.TAU.=180 for a turbulent-channel-type base flow with a periodic undulation in the spanwise direction in order to elucidate the generation mechanism of streamwise vorticity through the instab[...]texto impreso
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Nowadays, the most used techniques to design dense gas-solid flow reactors rely upon numerical predictions obtained from hydrodynamic models, usually derived through some averaging processes of the complete conservation equations. The averaging [...]texto impreso
We present numerically determined travelling-wave solutions for pressure-driven flow through a straight duct with a square cross-section. This family of solutions represents typical coherent structures (a staggered array of counter-rotating stre[...]texto impreso
Isothermal, incompressible flow in a straight duct with square cross-section is known to be linearly stable [1]. Direct numerical simulation, on the other hand, has revealed that turbulence in this geometry is self-sustained above a Reynolds num[...]texto impreso
Sekimoto, Atshushi ; Kawahara, Genta ; Sekiyama, K. ; Uhlmann, Markus ; Pinelli, Alfredo | American Institute of Physics | 2011Direct numerical simulations of fully developed turbulent flows in a horizontal square duct heated from below are performed at bulk Reynolds numbers Re(b) = 3000 and 4400 (based on duct width H) and bulk Richardson numbers 0texto impreso
Jiménez, J. ; Uhlmann, Markus ; Kawahara, Genta ; Pinelli, Alfredo | American Physical Society | 1999We have investigated a fully turbulent, low-Reynolds number plane channel with one impermeable and one porous wall. The latter is assumed to obey Darcy's law and to be mass-neutral in the mean. Our DNS data show an enhancement of wall friction u[...]texto impreso
Direct numerical simulations of streamwise-localized turbulent flow (turbulent puff) in a horizontal square duct heated from above are performed at Richardson numbers 0 ? Ri ? 0.58 to characterize differences between isothermal and non-isotherma[...]texto impreso
Jiménez, J. ; Uhlmann, Markus ; Pinelli, Alfredo ; Kawahara, Genta | Cambridge University Press | 2001The behaviour of turbulent shear flow over a mass-neutral permeable wall is studied numerically. The transpiration is assumed to be proportional to the local pressure fluctuations. It is first shown that the friction coefficient increases by up [...]texto impreso
Uhlmann, Markus ; Pinelli, Alfredo | 2003A two-dimensional model capable of simulating thermal convection flow in complex geometries has been implemented in a finite-difference setting and using a fictitious domain method of type “direct explicit forcing". The Boussinesq approximation [...]