On the ground of wharf and a station where coal is piled up, the sources polluting the atmosphere are mainly the raised coal dust. According to the principle of mechanics, with the consideration of the gravities of co...On the ground of wharf and a station where coal is piled up, the sources polluting the atmosphere are mainly the raised coal dust. According to the principle of mechanics, with the consideration of the gravities of coal dust particles and liquid droplets, coal dust size and humidity, under the condition of force balance when the coal dust was raised, the authors obtaineda theoretical formula for the threshold velocity of coal dust with humidity,Finally, the theoretical values from the formula gave a good agreement with the experimental data from some wind tunnels.展开更多
This paper presents a new kind of everage for the loeally-generated large vortexes so that the physieal quantities of the locally-generated large vortexes and the external large vortexes canberigorously separated from...This paper presents a new kind of everage for the loeally-generated large vortexes so that the physieal quantities of the locally-generated large vortexes and the external large vortexes canberigorously separated from the equal ions for the large vortexes proposed in a previous paper[1] To the equations for the two kinds of large vortexes, some auxiliary relations are introduced, and the value, of the length-scale lN of energy dissipation of the external large vortexes may he determined according to the actual circumstances of the disturbance of external sources. Thus the resulting equations of the second moments of turbulent velocity fluctuations for the two kinds of large vortexes can be made closed. Meanwhile, the corresponding coefficients of diffusion in the previous paper[1] are improved,Finally, a closed set of numerically-solvable equations of turbulence model are obtained.展开更多
If the vertically-mixing time is comparable with the period of oscillatory current, the contaminant contraction may occur, then the coefficient of shear dispersion will be negative (singularity). According to the two-...If the vertically-mixing time is comparable with the period of oscillatory current, the contaminant contraction may occur, then the coefficient of shear dispersion will be negative (singularity). According to the two-dimensional delay-diffusion equation derived by Liu in another paper, The equations for X(t), Y(t), central displacement as well as dispersion tensor were derived. Generally speaking, δDij/δτ is positive when τ is small; but when τ is large, the memory functions may be negative. The analytical expressions for Dij and X,Y were also given.展开更多
文摘On the ground of wharf and a station where coal is piled up, the sources polluting the atmosphere are mainly the raised coal dust. According to the principle of mechanics, with the consideration of the gravities of coal dust particles and liquid droplets, coal dust size and humidity, under the condition of force balance when the coal dust was raised, the authors obtaineda theoretical formula for the threshold velocity of coal dust with humidity,Finally, the theoretical values from the formula gave a good agreement with the experimental data from some wind tunnels.
基金The Project Supported by National Natural Science Foundation of China
文摘This paper presents a new kind of everage for the loeally-generated large vortexes so that the physieal quantities of the locally-generated large vortexes and the external large vortexes canberigorously separated from the equal ions for the large vortexes proposed in a previous paper[1] To the equations for the two kinds of large vortexes, some auxiliary relations are introduced, and the value, of the length-scale lN of energy dissipation of the external large vortexes may he determined according to the actual circumstances of the disturbance of external sources. Thus the resulting equations of the second moments of turbulent velocity fluctuations for the two kinds of large vortexes can be made closed. Meanwhile, the corresponding coefficients of diffusion in the previous paper[1] are improved,Finally, a closed set of numerically-solvable equations of turbulence model are obtained.
基金Project supported by National Natural Science Fundation of China
文摘If the vertically-mixing time is comparable with the period of oscillatory current, the contaminant contraction may occur, then the coefficient of shear dispersion will be negative (singularity). According to the two-dimensional delay-diffusion equation derived by Liu in another paper, The equations for X(t), Y(t), central displacement as well as dispersion tensor were derived. Generally speaking, δDij/δτ is positive when τ is small; but when τ is large, the memory functions may be negative. The analytical expressions for Dij and X,Y were also given.
