Trajectory prediction of a point mass particle in a predefined wall-bounded flow field with the objective of estimating its wall-impact velocity

作者：Houben J J H^*; Weiss Ch; Raupenstrauch H

来源：Computers & Fluids, 2012, 57: 172-182.

DOI：10.1016/j.compfluid.2011.12.017

• Computational fluid dynamics
• Euler-Langrange multiphase flow
• Particle impact speed
• Particle wall collision frequency
• Boundary layer

Some geometries used in 3D-CFD-simulations are so complex that it is impossible to create a boundary layer for each wall. Furthermore, the dimensions of the cells in the boundary layer will still be much larger than the particle's diameter in many industrial applications, which has the order of magnitude of 0.1-100 gm. As a consequence the speed of particles at the moment they impact on the wall is overestimated. Therefore, in this paper, a proposal is made for the calculation of a damping factor to estimate the final impact speed of diffusion-impaction and free flight particles without the use of a boundary layer. Five types of boundary layers are compared, for which analytical solutions based on a laminar, tangential flow field are evaluated. From these solutions a damping factor for the velocity is generated. With a simple case study it is shown that the resolution of the grid near the wall has large influence on the particle's impact speed and the rate of particles reaching the wall. The difference in impact speed is mainly caused by the overrated tangential velocity near the wall from the Taylor expansion around the cell's midpoint. With the correction factor the final impact speed is predicted better. Also the ratio of particles able to reach to wall becomes closer to the benchmark.

• 出版日期2012-3-30