Numerical Simulation of Multiphase Reactors with Continuous Liquid Phase

$F_{\text{D}}=-\frac{1}{2}{C}_{\text{D}}{\rho }_{\text{c}}\left(\frac{\pi d_{\text{p}}^2}{4}\right)\left|u_{\text{p}}-u_{\text{c}}\right|(u_{\text{p}}-u_{\text{c}})$

(2.95)

In fact, this equation is also the definition of the drag coefficient, C _D. Though it is well defined for a single particle, it is often used for particles with complex modes of motion. A single solid particle in steady motion is the most thoroughly studied case.

For the case of a spherical particle (including bubble and drop) in axisymmetric creeping flow (particle Reynolds number Re _p << 1) (Clift et al., 1978), the drag coefficient is analytically derived from the so-called Hadamard–Rybczynski solution of the flow field:

$C_{\text{D}}=-\frac{}{}$