Particles drag force

The pressure drop reflects the sum of single-particle drag-force contributions, which is (Foscolo and Gibilaro, 1984)... 

By equating the pressure gradient and the gas-particle drag force, the general momentum balance for the gas phase can be expressed as... 

This term denotes the particle-particle drag force. Moreover, the particle-particle drag coefficient derived by Chao [21] includes two contributions the peculiar drag coefficient and the fluid dynamic drag coefficient ... 

The normal relative velocity represents the binary velocity difference for head-on collision, the tangential velocity g j denotes the relative sliding on the particle surfaces, and the angular velocity o 2i denotes the relative rolling of the binary particles. Accordingly, three corresponding particle-particle drag forces, F"j, and, F j, and. 

Binary particle-particle drag force derived from the fluid dynamic velocity difference between the two particle types... 

Binary particle-particle drag force derived from the peculiar velocity difference between the two particle types (N/m ) Combined lift-virtual mass force acting on a collection of particles per unit mixture volume (N/m )... 

Within CFD-DEM, the granular temperature is a smoothed macroscopic variable. So this addition will shift the average, but not influence the variability. Clearly, the difference between variabihty of the individual particle drag force experienced in DNS and CFD-DEM is due to the smoothed nature of the unresolved flow field in CFD-DEM. 

Some empirical equations to predict cyclone pressure drop have been proposed (165,166). One (166) rehably predicts pressure drop under clean air flow for a cyclone having the API model dimensions. Somewhat surprisingly, pressure drop decreases with increasing dust loading. One reasonable explanation for this phenomenon is that dust particles approaching the cyclone wall break up the boundary layer film (much like spoiler knobs on an airplane wing) and reduce drag forces. 

If the particle is at a given radius from the center of rotation, the plasma now has to apply an inward drag force, E, on the cell to maintain the position of the particle ... 

When this inward drag force, is exceeded by the plasma, the particle moves inward with the plasma. The inward velocity the plasma needs to exceed in order to drag the particle inward is called the critical velocity, U, of the particle ... 

Viscous Drag. The velocity, v, with which a particle can move through a Hquid in response to an external force is limited by the viscosity, Tj, of the Hquid. At low velocity or creeping flow (77 < 1), the viscous drag force is /drag — SirTf- Dv. The Reynolds number (R ) is deterrnined from... 

A single particle settling in a gravity field is subjected primarily to drag force, gravity force, Ta-g-, and buoyancy, which have to be in... 

Whenever relative motion exists between a particle and a surrounding fluid, the fluid will exert a drag upon the particle. In steady flow, the drag force on the particle is... 

The drag force is exerted in a direction parallel to the fluid velocity. Equation (6-227) defines the drag coefficient. For some sohd bodies, such as aerofoils, a hft force component perpendicular to the liquid velocity is also exerted. For free-falling particles, hft forces are generally not important. However, even spherical particles experience lift forces in shear flows near solid surfaces. 

A particle falling under the action of gravity will accelerate until the drag force balances gravitational force, after which it falls at a constant terminal or free-settling velocity given by... 

Fluidized This is an expanded condition in which the sohds particles are supported by drag forces caused by the gas phase passing through the interstices among the particles at some critical velocity. It is an unstable condition in that the superficial gas velocity upward is less than the terminal setting velocity of the solids particles the gas... 

The motion oF Fine particles immersed in a moving tliiid is more greatly aFFected by tliiid drag Forces than that For similar large particles, For vei v small particles in a tliiid, particle motion approximates... 

The resistance to liquid flow aroimd particles may be presented by an equation similar to the viscosity equation but with considering the void fraction. Recall that the shear stress is expressed by the ratio of the drag force, R, to the active surface, K27td. The total sphere surface is Ttd and Kj is the coefficient accoimting for that part of the surface responsible for resistance. Considering the influence of void fraction as a function 2( ). we obtain ... 

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