An analysis of transport phenomena for multi-solid particle systems at higher Reynolds numbers by a 5th order polynomial Karman-Pohlhausen method

Abstract

Using the concentric spheres free surface model and a 5th order polynomial Karman-Pohlhausen method of the laminar boundary layer theory, the dimensionless tangential stress distributions, the dimensionless pressure distributions around a solid sphere in a swarm and the viscous, form and total drag coefficients for multi-solid sphere systems were numerically computed at higher Reynolds numbers, based on the first assumption that the pressure distribution equals that of potential flow between concentric spheres up to the separation point, and behind the separation point in the wake region the pressure does not recover and keeps constant, and on the second assumption that the pressure distribution varies according to the measurement of Flachsbart. The theoretical drag coefficient of single solid spheres in an infinite medium based on the second assumption agreed with the experimental data in the range of the Reynolds numbers from 3 × 10 2 to 10 5 . The friction factor for multi-solid particle systems based on the first assumption is almost the same as that on the 4th order polynomial and agreed with the experimental data of packed and distended beds. The void functions obtained from the drag coefficients for multi-solid particle systems based on both first and second assumptions were almost the same as the one on the 4th order polynomial. Using the velocity profiles based on concentric spheres free surface model and a 5th order polynomial Karman-Pohlhausen method of the laminar boundary layer obtained previously, the diffusion equation was solved numerically at higher Reynolds numbers on the first assumption of the pressure distribution around a solid sphere in a swarm equals that of potential flow between concentric spheres from the frontal stagnation point to the separation one, and the pressure does not recover, but keeps constant behind the separation point in the wake region. The mass transfer rate for multi-solid particle systems so computed was almost the same as that on the 4th order polynominal and agreed with the experimental data of single Solid spheres, and packed and particulate fluidized beds at higher Reynolds numbers.