Drag coefficient, influence

Therefore, the inertia forces have an insignificant influence on the sedimentation process in this regime. Theoretically, their influence is equal to zero. In contrast, the forces of viscous friction are at a maximum. Evaluating the coefficient B in equation 55 for a = 1 results in a value of 24. Hence, we have derived the expression for the drag coefficient of a sphere, = 24/Re. 

Drag coefficient The coefficient relating to the influence of drag over a surface in either laminar or turbulent flow. 

The drag coefficient for an antomohile body is typically estimated from wind-tunnel tests. In the wind tunnel, the drag force acting on a stationaiy model of the vehicle, or the vehicle itself, is measured as a stream of air is blown over it at the simulated vehicle speed. Drag coefficient depends primarily on the shape of the body, but in an actual vehicle is also influenced by other factors not always simulated in a test model. 

The mean velocity of migration Vj depends on the external driving force = ZjFE and on the resistance to motion set up by the medium s viscosity. This retarding force as a rule is proportional to the velocity. Under the influence of the external force, the velocity will increase until it attains the value Vj where the retarding force VjQ (9 is the drag coefficient) becomes equal to the external driving force. Hence,... 

Individual Particles. If the drag coefficient, j8, is influenced by the characteristics of individual particles, the detailed particle dynamics of the simplified scale models must be examined. In this case... 

Extensive comparisons of predictions and experimental results for drag on spheres suggest that the influence of non-Newtonian characteristics progressively diminishes as the value of the Reynolds number increases, with inertial effects then becoming dominant, and the standard curve for Newtonian fluids may be used with little error. Experimentally determined values of the drag coefficient for power-law fluids (1 < Re n < 1000 0.4 < n < 1) are within 30 per cent of those given by the standard drag curve 37 38. ... 

The study of the dynamical behavior of water molecules and protons as a function of the state of hydration is of great importance for understanding the mechanisms of proton and water transport and their coupling. Such studies can rationalize the influence of the random self-organized polymer morphology and water uptake on effective physicochemical properties (i.e., proton conductivity, water permeation rates, and electro-osmotic drag coefficients). 

Air resistance (or drag) is quantified by a dimensionless drag coefficient which is related to the external configuration of the rocket. Other factors that influence drag being the air density, the diameter of the rocket and the square of the rocket velocity. 

The shape of a drop moving under the influence of gravity may be affected by interfacial motions the drop may also wobble and move sideways (S27, W3). In one system (S22) the terminal velocity was reduced yielding a drag coefficient nearly equal to that of a solid particle. Interfacial convection tends to increase the rate of mass transfer above that which would occur in the absence of interfacial motion. The interaction between mass transfer and interfacial convection has been treated by Sawistowski (S7) and Davies (D4, D5). 

If the influence function r/(r) is known, the resistance-drag coefficient of a Brownian particle can be calculated (see Appendix E) as... 

The dimensionless drag coefficient cd (in meteorological practice the usual factor of 1/2 is omitted) is treated as isotropic and includes the influence of leaf and branch orientation, since the quantity a is the one-sided plant area density (m2/m3), not the cross-section exposed to the wind. Here, U is the scalar wind speed, while ui is the velocity vector in the -direction. 

In the book [117], some data are given on the hydrodynamic characteristics of bodies of various shapes these data mainly pertain to the region of precrisis self-similarity. The influence of roughness of the cylinder surface and the turbulence level of the incoming flow on the drag coefficient is discussed in [522]. In [211], the relationship between hydrodynamic flow characteristics in turbulent boundary layers and the longitudinal pressure gradient is studied. Analysis of the transition to turbulence in the wake of circular cylinders is presented in [333]. 

Under potential flow Ej, can be expressed by Sutherland s equation, by Langmuir s equation for a potential flow. Note that Langmuir obtained the equation from numerical calculations of the differential equations for the particle trajectory. In this equation the particle is considered as a point mass, i.e. the particle dimension is absent in Eq. (10.10). This means there is no direct influence of the particle dimension on the trajectory. However, the particle mass, the drag coefficient, and the Stokes number depend on the particle size, only later Langmuir s equation was derived for a finite particle size. This result cannot be used in... 

After determining the terminal velocity, the drag coefficient can be calculated using Equation 27.38. The terminal velocity of selected seed grains is summarized in Table 27.15. The indicated range reflects the influence of the geometric characteristics of different varieties and the different-sized kernels within the same variety. 

Mulbolland, J., Srivastava, R., and Wendt, J. Influence of droplet spacing on drag coefficient in nonevaporating, monodisperse streams. AIAA J. 26(10), 1231-1237, 1988. 

Note that the drop distortion parameters can influence the drop drag via its change of the cross-section and the drag coefficient because of the change of shape. Such investigations have been reported by Hwang et al. [23]. More importantly, the drop distortion parameters play a fundamental role in the determination of drop breakup and in the modeling of the atomization process. 

In this study, we were interested in the hydrodynamics on the one hand and its influence on the heat or mass transfer on the other hand. Recent numerical results based on the resolution of the Navier-Stokes equations and the heat equation were used to confront various correlations of the literature for the drag coefficient and the Nusselt number (or Sherwood number). 

The aerodynamic characteristics are determined by material, density, shape, drag coefficient, and atmospheric parameters such as temperature, pressure, and relative humidity. In addition to these parameters, the movement of a rod is strongly influenced by local winds, both horizontal and vertical components, and by wind turbulence and shear. 

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