The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Alfredo Pinelli - One of the best experts on this subject based on the ideXlab platform.
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traveling waves consistent with turbulence driven secondary flow in a square Duct
Physics of Fluids, 2010Co-Authors: Markus Uhlmann, Genta Kawahara, Alfredo PinelliAbstract:We present numerically determined traveling-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 streamwise vortices and an associated low-speed streak) on each wall. Their streamwise average flow in the cross-sectional plane corresponds to an eight-vortex pattern much alike the secondary flow found in the turbulent regime.
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travelling waves in a Straight square Duct
Advances in Turbulence XII - Proceedings of the 12th EUROMECH European Turbulence Conference, 2009Co-Authors: Markus Uhlmann, Genta Kawahara, Alfredo PinelliAbstract: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 number value of approximately 1100, based on the bulk velocity and the Duct half-width [2].
Surya Pratap Vanka - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulation of turbulence driven secondary flow in a square Duct
Physics of Fluids, 1991Co-Authors: Ravi K Madabhushi, Surya Pratap VankaAbstract:The fully developed turbulent flow in a Straight Duct of square cross section has been simulated using the large eddy simulation (LES) technique. A mixed spectral‐finite difference method has been used in conjunction with the Smagorinsky eddy‐viscosity model for the subgrid scales. The simulation was performed for a Reynolds number of 360 based on friction velocity (5810 based on bulk velocity) and Duct width. The simulation correctly predicted the existence of secondary flows and their effects on the mean flow and turbulence statistics. The results are in good qualitative agreement with the experimental data available at much higher Reynolds numbers. It is observed that both the Reynolds normal and shear stresses equally contribute to the proDuction of mean streamwise vorticity.
Markus Uhlmann - One of the best experts on this subject based on the ideXlab platform.
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traveling waves consistent with turbulence driven secondary flow in a square Duct
Physics of Fluids, 2010Co-Authors: Markus Uhlmann, Genta Kawahara, Alfredo PinelliAbstract:We present numerically determined traveling-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 streamwise vortices and an associated low-speed streak) on each wall. Their streamwise average flow in the cross-sectional plane corresponds to an eight-vortex pattern much alike the secondary flow found in the turbulent regime.
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travelling waves in a Straight square Duct
Advances in Turbulence XII - Proceedings of the 12th EUROMECH European Turbulence Conference, 2009Co-Authors: Markus Uhlmann, Genta Kawahara, Alfredo PinelliAbstract: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 number value of approximately 1100, based on the bulk velocity and the Duct half-width [2].
Ravi K Madabhushi - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulation of turbulence driven secondary flow in a square Duct
Physics of Fluids, 1991Co-Authors: Ravi K Madabhushi, Surya Pratap VankaAbstract:The fully developed turbulent flow in a Straight Duct of square cross section has been simulated using the large eddy simulation (LES) technique. A mixed spectral‐finite difference method has been used in conjunction with the Smagorinsky eddy‐viscosity model for the subgrid scales. The simulation was performed for a Reynolds number of 360 based on friction velocity (5810 based on bulk velocity) and Duct width. The simulation correctly predicted the existence of secondary flows and their effects on the mean flow and turbulence statistics. The results are in good qualitative agreement with the experimental data available at much higher Reynolds numbers. It is observed that both the Reynolds normal and shear stresses equally contribute to the proDuction of mean streamwise vorticity.
Lee N Benson - One of the best experts on this subject based on the ideXlab platform.
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stenting the neonatal arterial Duct in Duct dependent pulmonary circulation new techniques better results
Journal of the American College of Cardiology, 2004Co-Authors: Marc Gewillig, Derize Boshoff, Joseph Dens, Luc Mertens, Lee N BensonAbstract:Abstract Objectives The goal of this study was to assess a new approach to stent the arterial Duct in neonates with a Duct-dependent pulmonary circulation. Background Previous attempts to stent the neonatal arterial Duct were unsatisfactory. Learning from these failures, we speculated that covering the complete length of the Duct with current low-profile stents might avoid previous problems. Methods Ten neonates with Duct-dependent pulmonary circulations through a short Straight Duct were treated with stent implantation. The Duct was crossed with an atraumatic 0.014-inch wire. A low-profile premounted coronary stent (outer diameter Results All stents could safely be deployed with adequate pulmonary flow at early- and medium-term follow-up. There were no procedure-related complications; one patient died early from sepsis. All patients had adequate relief of cyanosis for at least three to four months. During follow-up, the pulmonary vasculature bed had grown without distortion. Acute occlusion of a stented Duct was not observed. Ductal flow progressively decreased slowly over several months by luminal narrowing, until the stented Duct had either become redundant or was dilated/restented or until elective staged surgery was performed. Conclusions With current technology, complete stenting of a short Straight Duct is a safe and effective palliation, allowing adequate growth of the pulmonary arteries.
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stenting the neonatal arterial Duct in Duct dependent pulmonary circulation new techniques better results
Journal of the American College of Cardiology, 2004Co-Authors: Marc Gewillig, Derize Boshoff, Joseph Dens, Luc Mertens, Lee N BensonAbstract:OBJECTIVES The goal of this study was to assess a new approach to stent the arterial Duct in neonates with a Duct-dependent pulmonary circulation. BACKGROUND Previous attempts to stent the neonatal arterial Duct were unsatisfactory. Learning from these failures, we speculated that covering the complete length of the Duct with current low-profile stents might avoid previous problems. METHODS Ten neonates with Duct-dependent pulmonary circulations through a short Straight Duct were treated with stent implantation. The Duct was crossed with an atraumatic 0.014-inch wire. A low-profile premounted coronary stent (outer diameter <4F, length 13 to 24 mm, diameter 3.0 to 4.0 mm) was positioned within the Duct, not protected by a sheath; care was taken to cover the complete length of the Duct from the aortaDuctal junction until well within the pulmonary trunk. RESULTS All stents could safely be deployed with adequate pulmonary flow at early- and medium-term follow-up. There were no procedure-related complications; one patient died early from sepsis. All patients had adequate relief of cyanosis for at least three to four months. During follow-up, the pulmonary vasculature bed had grown without distortion. Acute occlusion of a stented Duct was not observed. Ductal flow progressively decreased slowly over several months by luminal narrowing, until the stented Duct had either become redundant or was dilated/restented or until elective staged surgery was performed. CONCLUSIONS With current technology, complete stenting of a short Straight Duct is a safe and effective palliation, allowing adequate growth of the pulmonary arteries.
