Without any other approximations apart from the spectral method which is employed,the energy spectra corresponding to two kinds of'negative temperatures'are simulated with a symmetric trapezium truncation.The ...Without any other approximations apart from the spectral method which is employed,the energy spectra corresponding to two kinds of'negative temperatures'are simulated with a symmetric trapezium truncation.The simulated results with either of the two negative temperatures are reasonably consistent with those from the statistical theory of turbulence.The more usual case for two positive temperatures evolves differently from the theoretical prediction.The viscosity influence on the ergodicity is discussed. It is shown that two--dimensional(2D)ideal flows on thesphere have a less pronounced tendency to be ergodic than those on planar geometry due to the curvature of thespherical surface that weakens the interaction between different parts of the flow,enabling these parts to behave inmore relative isolation. The expressions for the standard deviations from a canonical ensemble for the two differentoptions of coefficients are shown to be proportional to in(N is the total number of independent modes in the system),independent of the initial conditions of the system.展开更多
During the process of pneumatic conveying of fine particles, the flow mode may change from dense to dilute. In studying this mode change, we evaluate three parameters （Hurst exponent, Shannon entropy, and phase-space...During the process of pneumatic conveying of fine particles, the flow mode may change from dense to dilute. In studying this mode change, we evaluate three parameters （Hurst exponent, Shannon entropy, and phase-space attractor size） used in signal analysis. Experimental data of pneumatic conveying of fly ash at three locations along a 173-m-long pipeline were used for this analysis. Variations in magnitude of the Hurst exponent, Shannon entropy, and size of the phase space attractor exhibit different trends in their variations for dense and dilute mode of flow. From these trends it is possible to predict the change from dense to dilute mode and the location along the length of the pipeline of this change in mode of flow.展开更多
文摘Without any other approximations apart from the spectral method which is employed,the energy spectra corresponding to two kinds of'negative temperatures'are simulated with a symmetric trapezium truncation.The simulated results with either of the two negative temperatures are reasonably consistent with those from the statistical theory of turbulence.The more usual case for two positive temperatures evolves differently from the theoretical prediction.The viscosity influence on the ergodicity is discussed. It is shown that two--dimensional(2D)ideal flows on thesphere have a less pronounced tendency to be ergodic than those on planar geometry due to the curvature of thespherical surface that weakens the interaction between different parts of the flow,enabling these parts to behave inmore relative isolation. The expressions for the standard deviations from a canonical ensemble for the two differentoptions of coefficients are shown to be proportional to in(N is the total number of independent modes in the system),independent of the initial conditions of the system.
文摘During the process of pneumatic conveying of fine particles, the flow mode may change from dense to dilute. In studying this mode change, we evaluate three parameters （Hurst exponent, Shannon entropy, and phase-space attractor size） used in signal analysis. Experimental data of pneumatic conveying of fly ash at three locations along a 173-m-long pipeline were used for this analysis. Variations in magnitude of the Hurst exponent, Shannon entropy, and size of the phase space attractor exhibit different trends in their variations for dense and dilute mode of flow. From these trends it is possible to predict the change from dense to dilute mode and the location along the length of the pipeline of this change in mode of flow.
