Two-dimensional Navier-Stokes equations and energy equation governing incompressible laminar flow past a bundle of cylinders were numerically solved by using the finite element method. The velocity correction method w...Two-dimensional Navier-Stokes equations and energy equation governing incompressible laminar flow past a bundle of cylinders were numerically solved by using the finite element method. The velocity correction method was used for time advancement, and spatial discretization was carried out with the Galerkin weighted residual method. Viscous flows past the cylinder banks arranged in in-line cylinder bundles and staggered cylinder bundles, coupled with heat transfer, were investigated for pitch-diameter ratios of 1.5 and 2.0 and the Reynolds numbers from 50 to 500. Flow structures and heat transfer behavior were discussed. The results obtained agree well with available numerical data.展开更多
Vortex shedding from a circular cylinder subjected to fortal oscillations at arbitrary angles(as shown in Fis. 1 for 0°<β<90°) with respect to the free stream is numerically investigated using the Nav...Vortex shedding from a circular cylinder subjected to fortal oscillations at arbitrary angles(as shown in Fis. 1 for 0°<β<90°) with respect to the free stream is numerically investigated using the Navier-Stokes equations. The emphasis of this study is put on revealing the complicated vortex structures and their evolution in the near wake. In the present study, a number of possible vortex modes are also numerically simulated, and a variety of physical phenomena are duplicated and even renewed numerically. A parameter map indicating the classification of preferred vortex modes is firstly given in the frequency-amplitude plane.展开更多
Turbulent channel flows with consideration of the buoyancy effect of the bubble phase is investigated by means of the Direct Numerical Simulation （DNS）. This two-phase system is solved by a two-way coupling Lagrangi...Turbulent channel flows with consideration of the buoyancy effect of the bubble phase is investigated by means of the Direct Numerical Simulation （DNS）. This two-phase system is solved by a two-way coupling Lagrangian-Eulerian approach. The Reynolds number based on the friction velocity and the half-width of the channel is 194, and the gravitational acceleration varies from -0.5 to 0.5, ranging from the upflow to the downflow cases. This study aims to reveal the influence of buoyancy on the turbulence behavior and the bubble motion. Some typical statistical quantities, including the averaged velocities and velocity fluctuations for the fluid and bubble phases, as well as the flow structures of the turbulence fluctuations, are analyzed.展开更多
基金The project supported by the Natural Science Foundation of China.(No.19889210)
文摘Two-dimensional Navier-Stokes equations and energy equation governing incompressible laminar flow past a bundle of cylinders were numerically solved by using the finite element method. The velocity correction method was used for time advancement, and spatial discretization was carried out with the Galerkin weighted residual method. Viscous flows past the cylinder banks arranged in in-line cylinder bundles and staggered cylinder bundles, coupled with heat transfer, were investigated for pitch-diameter ratios of 1.5 and 2.0 and the Reynolds numbers from 50 to 500. Flow structures and heat transfer behavior were discussed. The results obtained agree well with available numerical data.
文摘Vortex shedding from a circular cylinder subjected to fortal oscillations at arbitrary angles(as shown in Fis. 1 for 0°<β<90°) with respect to the free stream is numerically investigated using the Navier-Stokes equations. The emphasis of this study is put on revealing the complicated vortex structures and their evolution in the near wake. In the present study, a number of possible vortex modes are also numerically simulated, and a variety of physical phenomena are duplicated and even renewed numerically. A parameter map indicating the classification of preferred vortex modes is firstly given in the frequency-amplitude plane.
基金supported by the National Natural Science Foundation of China(Grant Nos.10772173,10972211 and 11072236)the Fundamental Research Funds for the Central Universitiesthe Science and Technology Innovation Foundation of the Chinese Academy of Sciences(Grant No.CXJJ-11-M69)
文摘Turbulent channel flows with consideration of the buoyancy effect of the bubble phase is investigated by means of the Direct Numerical Simulation （DNS）. This two-phase system is solved by a two-way coupling Lagrangian-Eulerian approach. The Reynolds number based on the friction velocity and the half-width of the channel is 194, and the gravitational acceleration varies from -0.5 to 0.5, ranging from the upflow to the downflow cases. This study aims to reveal the influence of buoyancy on the turbulence behavior and the bubble motion. Some typical statistical quantities, including the averaged velocities and velocity fluctuations for the fluid and bubble phases, as well as the flow structures of the turbulence fluctuations, are analyzed.
