The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet ...The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet dynamics,are demonstrated in the current research.Hereby,the 2nd Stokes problem assumes that the surface,with a thin shared layer of the fluid on it,oscillates in a harmonic manner along the x-axis of the rivulet flow,which coincides with the main flow direction streaming down the underlying surface.We obtain the exact extension of the rivulet flow family,clarifying the structure of the pressure field,which fully absorbs the arising perturbation.The profile of the velocity field is assumed to be Gaussian-type with a non-zero level of plasticity.Hence,the absolutely non-Newtonian case of the viscoplastic flow solution,which satisfies the motion and continuity equations,is considered(with particular cases of exact solutions for pressure).The perturbed governing equations of motion for rivulet flows then result in the Riccati-type ordinary differential equation(ODE),describing the dynamics of the coordinate x(t).The approximated schematic dynamics are presented in graphical plots.展开更多
A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented. A series of cable section models of different mass and stiffness and damping ratio were. designed with artificial...A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented. A series of cable section models of different mass and stiffness and damping ratio were. designed with artificial rivulet. They were tested in smooth flow under different wind speed and yaw angle and for different position of artificial rivulet. The measured response of cable models was then analyzed and compared with the experimental results obtained by other researchers and the existing theories for wind-induced cable vibration. The results show that the measured response of horizontal cable models with artificial rivulet could be well predicted by Den Hartog' s galloping theory when wind is normal to the cable axis. For the wind with certain yaw angles, the cable models with artificial rivulet exhibit velocity-restricted response characteristics.展开更多
Combining lubrication theory and CFD technology, a finite element model is established to simulate the rain-wind-induced vibration(RWIV). Based on Spalart-Allmaras(S-A)turbulence type, COMSOL software is adopted to ca...Combining lubrication theory and CFD technology, a finite element model is established to simulate the rain-wind-induced vibration(RWIV). Based on Spalart-Allmaras(S-A)turbulence type, COMSOL software is adopted to calculate the wind pressure coefficient and wind friction coefficient that vary with the location and time. To verify the veracity and rationality of this method, the formation and evolution of rivulets at different wind speeds are studied and compared with the existing experimental results. Furthermore, the time, location, height and width of the initial formation of rivulets are analyzed at different wind speeds, cable inclination angles and wind yaw angles. The results show that the three influencing factors mentioned above have great effect on the formation of rivulet, and the influencing tendency, range and degree are different from each other.展开更多
文摘The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet dynamics,are demonstrated in the current research.Hereby,the 2nd Stokes problem assumes that the surface,with a thin shared layer of the fluid on it,oscillates in a harmonic manner along the x-axis of the rivulet flow,which coincides with the main flow direction streaming down the underlying surface.We obtain the exact extension of the rivulet flow family,clarifying the structure of the pressure field,which fully absorbs the arising perturbation.The profile of the velocity field is assumed to be Gaussian-type with a non-zero level of plasticity.Hence,the absolutely non-Newtonian case of the viscoplastic flow solution,which satisfies the motion and continuity equations,is considered(with particular cases of exact solutions for pressure).The perturbed governing equations of motion for rivulet flows then result in the Riccati-type ordinary differential equation(ODE),describing the dynamics of the coordinate x(t).The approximated schematic dynamics are presented in graphical plots.
文摘A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented. A series of cable section models of different mass and stiffness and damping ratio were. designed with artificial rivulet. They were tested in smooth flow under different wind speed and yaw angle and for different position of artificial rivulet. The measured response of cable models was then analyzed and compared with the experimental results obtained by other researchers and the existing theories for wind-induced cable vibration. The results show that the measured response of horizontal cable models with artificial rivulet could be well predicted by Den Hartog' s galloping theory when wind is normal to the cable axis. For the wind with certain yaw angles, the cable models with artificial rivulet exhibit velocity-restricted response characteristics.
基金Supported by the National Natural Science Foundation of China(No.51408399)
文摘Combining lubrication theory and CFD technology, a finite element model is established to simulate the rain-wind-induced vibration(RWIV). Based on Spalart-Allmaras(S-A)turbulence type, COMSOL software is adopted to calculate the wind pressure coefficient and wind friction coefficient that vary with the location and time. To verify the veracity and rationality of this method, the formation and evolution of rivulets at different wind speeds are studied and compared with the existing experimental results. Furthermore, the time, location, height and width of the initial formation of rivulets are analyzed at different wind speeds, cable inclination angles and wind yaw angles. The results show that the three influencing factors mentioned above have great effect on the formation of rivulet, and the influencing tendency, range and degree are different from each other.
