This paper presents the results of an experimental study on the influences of floodplain impermeable groynes on flow structure, velocity, and water depth around the groyne（s）. A wooden symmetrical compound channel w...This paper presents the results of an experimental study on the influences of floodplain impermeable groynes on flow structure, velocity, and water depth around the groyne（s）. A wooden symmetrical compound channel was used. Groyne models with three different groyne relative lengths, 0.5, 0.75, and 1.0, were used on one floodplain with single and series arrangements. Analysis of the experimental results using the measured flow velocity and water depth values showed that flow structure, velocity, and water depth mainly depend on groyne relative length and the relative distance between series groynes. The flow velocity at the main channel centerline increased by about 40%, 60%, and 85%, and in other parts on the horizontal plane at the floodplain mid-water, depth by about 75%, 125%, and 175% of its original value in eases of one-side floodplain groyne（s） with relative lengths of 0.5, 0.75, and 1.0, respectively. The effective distance between two groynes in series arrangement ranges from 3 to 4 times the groyne length. Using an impermeable groyne with a large relative length in river floodplains increases the generation of eddy and roller zones downstream of the groyne, leading to more scouring and deposition. To avoid that, the groyne relative length must be kept below half the floodplain width,展开更多
In this paper, the influence of heat transfer and induced magnetic field on peristaltic flow of a Johnson-Segalman fluid is studied. The purpose of the present investigation is to study the effects of induced magnetic...In this paper, the influence of heat transfer and induced magnetic field on peristaltic flow of a Johnson-Segalman fluid is studied. The purpose of the present investigation is to study the effects of induced magnetic field on the peristaltic flow of non-Newtonian fluid. The two-dimensional equations of a Johnson-Segalman fluid are simplified by assuming a long wavelength and a low Reynolds number. The obtained equations are solved for the stream function, magnetic force function, and axial pressure gradient by using a regular perturbation method. The expressions for the pressure rise, temperature, induced magnetic field, pressure gradient, and stream function are sketched and interpreted for various embedded parameters.展开更多
A globally optimal solution to vector quantization (VQ) index assignment on noisy channel, the evolutionary algorithm based index assignment algorithm (EAIAA), is presented. The algorithm yields a significant reductio...A globally optimal solution to vector quantization (VQ) index assignment on noisy channel, the evolutionary algorithm based index assignment algorithm (EAIAA), is presented. The algorithm yields a significant reduction in average distortion due to channel errors, over conventional arbitrary index assignment, as confirmed by experimental results over the memoryless binary symmetric channel (BSC) for any bit error.展开更多
Stage-discharge curves are particularly important in river basin management. For a compound channel, the stage-discharge curve is often difficult to be extrapolated to yield estimates of level for a given frequency of...Stage-discharge curves are particularly important in river basin management. For a compound channel, the stage-discharge curve is often difficult to be extrapolated to yield estimates of level for a given frequency of flow. By analyzing a large number of experimental data from Science and Engineering Research Council Flood Channel Facility (SERC-FCF) and applying system dynamics method, the authors established system dynamics model of conveyance capacity when rivers flow in an overbank mode, spilling onto the adjoining flood plain. The model was applied to a compound channel. And the corresponding simulated results are shown to attain high accurcy.展开更多
Numerical results of three-dimensional separated flow and heat transfer in an enlarged rectangular channel are presented in this paper.The expansion ratio and aspect ratio of the channel are 2.0 and 16.0,respectively....Numerical results of three-dimensional separated flow and heat transfer in an enlarged rectangular channel are presented in this paper.The expansion ratio and aspect ratio of the channel are 2.0 and 16.0,respectively.Reynolds number of the flow is 200 and it is over the critical Reynolds number.Over the critical Reynolds number,the flow in the symmetric channel becomes asymmetric and deflects to one side of the walls.Effects of the pulsating fluctuation at the inlet upon the flow in the channel are investigated.It is clarified that the inlet flow with a pulsating fluctuation of Strouhal number 0.05 and 0.10 strongly affects on the flow in the channel,and heat transfer on the walls is enhanced,especially on the wall surface covered with long separation bubble.On the other hand,the pulsation of St=0.0125 oscillates the shear layer more weakly than that of St=0.05,0.10 and the enhancement of heat transfer is smaller,though some vortices are shed from the vicinity of the side wall near the reattachment region.The oscillation of the main flow calms down gradually as the Strouhal number of the pulsation increases over 0.10.The influence of pulsation of St=0.20 on the flow is restricted in the near downstream of the step,and heat transfer on the walls is almost similar to that of the steady flow in the channel.展开更多
Numerical results of three-dimensional separated flow and heat transfer in a rectangular channel with a sudden expansion are presented in this paper. Numerical simulations of Navier-Stokes and energy equations are car...Numerical results of three-dimensional separated flow and heat transfer in a rectangular channel with a sudden expansion are presented in this paper. Numerical simulations of Navier-Stokes and energy equations are carried out using the finite difference method. The results of three-dimensional calculations are compared with the two-dimensional ones, and effects of the aspect ratio of channel upon the flow are shown. The transition from symmetric to asymmetric flow appears at lower Reynolds number as increasing the aspect ratio. The details of local heat transfer characteristics in two different separated flow regions on two downstream walls are clarified. Two-dimensionality of the flow and heat transfer almost disappears for the aspect ratio considered.展开更多
In this paper, the consequences of cilia motion are reflected by the CNTs nanoparticles. The problem is expressed in a symmetric channel with ciliated walls. Exact solutions of the governing flow problem are obtained ...In this paper, the consequences of cilia motion are reflected by the CNTs nanoparticles. The problem is expressed in a symmetric channel with ciliated walls. Exact solutions of the governing flow problem are obtained for pressure gradient, temperature and velocities of the fluid. Streamlines for the velocity profile are plotted to discuss the trapping phenomenon.展开更多
The impulsion system of cilia motion is deliberated by biviscosity fluid model. The problem of two-dimensional motion of biviscosity fluid privileged in a symmetric channel with ciliated walls is considered. The feat...The impulsion system of cilia motion is deliberated by biviscosity fluid model. The problem of two-dimensional motion of biviscosity fluid privileged in a symmetric channel with ciliated walls is considered. The features of ciliary structures are resolute by the supremacy of viscous effects above inertial possessions by the long-wavelength and low Reynolds approximation. Closed-form solutions for the longitudinal pressure gradient, temperature and velocities are obtained. The pressure gradient and volume flow rate for different values of the biviscosity are also premeditated. The flow possessions for the biviscosity fluid resolute as a function of the cilia and metachronal wave velocity.展开更多
文摘This paper presents the results of an experimental study on the influences of floodplain impermeable groynes on flow structure, velocity, and water depth around the groyne（s）. A wooden symmetrical compound channel was used. Groyne models with three different groyne relative lengths, 0.5, 0.75, and 1.0, were used on one floodplain with single and series arrangements. Analysis of the experimental results using the measured flow velocity and water depth values showed that flow structure, velocity, and water depth mainly depend on groyne relative length and the relative distance between series groynes. The flow velocity at the main channel centerline increased by about 40%, 60%, and 85%, and in other parts on the horizontal plane at the floodplain mid-water, depth by about 75%, 125%, and 175% of its original value in eases of one-side floodplain groyne（s） with relative lengths of 0.5, 0.75, and 1.0, respectively. The effective distance between two groynes in series arrangement ranges from 3 to 4 times the groyne length. Using an impermeable groyne with a large relative length in river floodplains increases the generation of eddy and roller zones downstream of the groyne, leading to more scouring and deposition. To avoid that, the groyne relative length must be kept below half the floodplain width,
文摘In this paper, the influence of heat transfer and induced magnetic field on peristaltic flow of a Johnson-Segalman fluid is studied. The purpose of the present investigation is to study the effects of induced magnetic field on the peristaltic flow of non-Newtonian fluid. The two-dimensional equations of a Johnson-Segalman fluid are simplified by assuming a long wavelength and a low Reynolds number. The obtained equations are solved for the stream function, magnetic force function, and axial pressure gradient by using a regular perturbation method. The expressions for the pressure rise, temperature, induced magnetic field, pressure gradient, and stream function are sketched and interpreted for various embedded parameters.
文摘A globally optimal solution to vector quantization (VQ) index assignment on noisy channel, the evolutionary algorithm based index assignment algorithm (EAIAA), is presented. The algorithm yields a significant reduction in average distortion due to channel errors, over conventional arbitrary index assignment, as confirmed by experimental results over the memoryless binary symmetric channel (BSC) for any bit error.
文摘Stage-discharge curves are particularly important in river basin management. For a compound channel, the stage-discharge curve is often difficult to be extrapolated to yield estimates of level for a given frequency of flow. By analyzing a large number of experimental data from Science and Engineering Research Council Flood Channel Facility (SERC-FCF) and applying system dynamics method, the authors established system dynamics model of conveyance capacity when rivers flow in an overbank mode, spilling onto the adjoining flood plain. The model was applied to a compound channel. And the corresponding simulated results are shown to attain high accurcy.
基金These results were partly obtained with a supercomputer SX-9 of Cyberscience Center,Tohoku University
文摘Numerical results of three-dimensional separated flow and heat transfer in an enlarged rectangular channel are presented in this paper.The expansion ratio and aspect ratio of the channel are 2.0 and 16.0,respectively.Reynolds number of the flow is 200 and it is over the critical Reynolds number.Over the critical Reynolds number,the flow in the symmetric channel becomes asymmetric and deflects to one side of the walls.Effects of the pulsating fluctuation at the inlet upon the flow in the channel are investigated.It is clarified that the inlet flow with a pulsating fluctuation of Strouhal number 0.05 and 0.10 strongly affects on the flow in the channel,and heat transfer on the walls is enhanced,especially on the wall surface covered with long separation bubble.On the other hand,the pulsation of St=0.0125 oscillates the shear layer more weakly than that of St=0.05,0.10 and the enhancement of heat transfer is smaller,though some vortices are shed from the vicinity of the side wall near the reattachment region.The oscillation of the main flow calms down gradually as the Strouhal number of the pulsation increases over 0.10.The influence of pulsation of St=0.20 on the flow is restricted in the near downstream of the step,and heat transfer on the walls is almost similar to that of the steady flow in the channel.
文摘Numerical results of three-dimensional separated flow and heat transfer in a rectangular channel with a sudden expansion are presented in this paper. Numerical simulations of Navier-Stokes and energy equations are carried out using the finite difference method. The results of three-dimensional calculations are compared with the two-dimensional ones, and effects of the aspect ratio of channel upon the flow are shown. The transition from symmetric to asymmetric flow appears at lower Reynolds number as increasing the aspect ratio. The details of local heat transfer characteristics in two different separated flow regions on two downstream walls are clarified. Two-dimensionality of the flow and heat transfer almost disappears for the aspect ratio considered.
文摘In this paper, the consequences of cilia motion are reflected by the CNTs nanoparticles. The problem is expressed in a symmetric channel with ciliated walls. Exact solutions of the governing flow problem are obtained for pressure gradient, temperature and velocities of the fluid. Streamlines for the velocity profile are plotted to discuss the trapping phenomenon.
文摘The impulsion system of cilia motion is deliberated by biviscosity fluid model. The problem of two-dimensional motion of biviscosity fluid privileged in a symmetric channel with ciliated walls is considered. The features of ciliary structures are resolute by the supremacy of viscous effects above inertial possessions by the long-wavelength and low Reynolds approximation. Closed-form solutions for the longitudinal pressure gradient, temperature and velocities are obtained. The pressure gradient and volume flow rate for different values of the biviscosity are also premeditated. The flow possessions for the biviscosity fluid resolute as a function of the cilia and metachronal wave velocity.
