From the following four aspects: drag forces, velocity, energy and sediment carrying capability of slope surface flow, the threshold gradient of slope surface erosion in the granite area in the south of china is discussed, and it is obtained the critical slope gradient is from 35 to 43 degree.

In the dissertation, the drag forces acting on the square-section cylinder are surveyed in the flume, and attention is pay to the two factors:(1) The effect of cylinder shape to the drag force.

The result indicates that calculated wave drag forces by the commonly used linerarization method are more than 5 % less than the nonlinear values measured by the mean square errors.

The results indicate that the wave drag forces calculated by linear wave theory are larger than those calculated by the third order Stokes wave theory for given waves.

Under the condition of giving a series of initial frictional resistant coefficients of soil around the pile, the loads of pile cap, the drag forces of pile end and the frictional resistances of soil around the pile are calculated by using the method of iteration.

However, further work is required to clarify whether both the coupling relationship and the calculation of drag forces based on the two-fluid model are acceptable.

The IPSA model solves the Navier-Stokes equations of each phase with the interphase interactions between two phases of water and air, including the interphase drag forces, interphase lift forces, interphase pressure and virtual mass forces.

Different coupling relations between phases and way of calculating drag forces used to simulate gas-solid fluidized beds, are based on the simplified hard-sphere model.

Both surface tension and fluid drag forces are considered in formulating the penetration behavior of ceramic particulates.

Analytical estimates, assuming the assembly to be a solid sphere of equivalent surface area, predicted drag forces about two orders of magnitude lower than the corresponding experimental values.

Measurement and computation of drag forces in thermogravimetric studies

From the model, it was clear that the lateral lift force is responsible for plume spreading, whereas lateral drag forces bend the plume.

This balance included the buoyancy and the viscous drag forces.

Taking consideration of the feedback on the vertical motion due to the drag force and the cooling effect acted on the air by raindrops, a system of differential, equations for the vertical velocity, temperature difference between cloud and environment and the water content is introduced. The solutions are. analysed numerically, for five sets of different, parameters. , From the. analysis the effect of different intensity of precipitation, stratification, initial condition and environment are studied, and...

Taking consideration of the feedback on the vertical motion due to the drag force and the cooling effect acted on the air by raindrops, a system of differential, equations for the vertical velocity, temperature difference between cloud and environment and the water content is introduced. The solutions are. analysed numerically, for five sets of different, parameters. , From the. analysis the effect of different intensity of precipitation, stratification, initial condition and environment are studied, and it is further found that under the influence of precipitation process, the vertical velocity, temperature difference and water content in cloud are reduced very quickly, and the descending motion appeas rapidly first at the cloud base, then spreads upward. Thus, starting from the cloud base, the cloud dissipates rapidly. This resembles the observed process of the dissipation of a precipitating cloud.

It is difficult to consider the exact dynamic effect of irregular waves on an isolated pile by spectral method if the drag force has to be taken into co- sideration, because the drag force is nonlinear according to Morison's Equa- tion. In order to overcome this difficulty, a more practical and effective method of wave simulation is introduccd in this paper. The characteristic of the wave forces obtained through simulation is analysed and discussed. Moreover,the application of the method of...

It is difficult to consider the exact dynamic effect of irregular waves on an isolated pile by spectral method if the drag force has to be taken into co- sideration, because the drag force is nonlinear according to Morison's Equa- tion. In order to overcome this difficulty, a more practical and effective method of wave simulation is introduccd in this paper. The characteristic of the wave forces obtained through simulation is analysed and discussed. Moreover,the application of the method of probability distribution for this case is also discussed.the four methods of computation are analysed and com- pared by means of four illustrative examples having different pile diameters.

This paper deals with the preliminary experimental study of drag reduction by adding minute quantity of polyacrylamide, a water-soluble longchain high molecular polymer, into tube flow of clear water and muddy water. Tests were performed in two tubes of inside diameters of 0.682 and 0.798 cm respectively. The mean grain diameters d_(50) of suspended sediment are 0.0052 and 0.0185 mm respectively. The consistency of polymer in the flow is 5-100 ppm. Data measured from tests in clear water agrees with von...

This paper deals with the preliminary experimental study of drag reduction by adding minute quantity of polyacrylamide, a water-soluble longchain high molecular polymer, into tube flow of clear water and muddy water. Tests were performed in two tubes of inside diameters of 0.682 and 0.798 cm respectively. The mean grain diameters d_(50) of suspended sediment are 0.0052 and 0.0185 mm respectively. The consistency of polymer in the flow is 5-100 ppm. Data measured from tests in clear water agrees with von Karman's drag equation for turbulent flow in smooth tube. The rule of drag variation, conditions of drag reduction and the relation between drag reduction effect and the related parameters for flow of clear water and muddy water with polymer additives are presented in the paper. The effect of drag reduction increases with the consistency of polymer and the flow velocity. The maximum drag reduction is up to 71% for clear water and 39％ for muddy water which is less than that for clear water under the same test condition. The effect of drag reduction decreases as the concentration of sediment in muddy water increases, and the effect of sediment grain size on drag reduction is not obvious. The drag equation (4)for clear water flow with polymer addi tives (1/f~(1/2))_p=4log(Re_1f(1/2)_p-0.4+A (4) is presented in the paper, This equation conforms with the experimental results on the whole. For muddy water flow with polymer additives, not only the drag force decreases, the critical velocity also decreases. When the concentration of muddy water S_v=20％, the critical velocity V_D decreases about 30％, thus the flow characteristics and the economic index of muddy water flow will be improved. This is of great importance for the long distance transportation of sediment and the full use of water and sediment resources.