Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
A particle-center-averaged Euler-Euler model for bubbly flow simulations
An inconsistency exists in bubble force models used in the standard Euler-Euler simulations. The bubble force models are typically developed by assuming that the forces act on the bubbles' centers of mass. However, in the standard Euler-Euler model, each bubble force is a function of the local gas volume fraction because the phase-averaging method is used. This inconsistency can lead to gas over-concentration in the center or near the wall of a channel when the bubble diameter is larger than the computational cell size. Besides, a mesh-independent solution may not exist in such cases. In addition, the bubble dimension is not fully considered in the standard Euler-Euler model.
In the present study, a particle-center-averaging method is used to represent the bubble forces as forces that act on the bubbles' centers of mass. A particle-center-averaged Euler-Euler approach for bubbly flow simulations is developed by combining the particle-center-averaged Euler-Euler framework with a Gaussian convolution method. The convolution method is used to convert the phase-averaged and the particle-center-averaged quantities. The test results illustrate that the particle-center-averaging method alleviates the over-prediction of the gas volume fraction peak in the channel center and provides a mesh-independent solution. In the particle-center-averaged Euler-Euler model, the bubble dimension is fully considered and bubble deformation can be considered by using anisotropic diffusion in quantities conversion.
Keywords: CFD; bubbly flow; Euler-Euler
International Conference on Numerical Methods in Multiphase Flows 4, 28.-30.09.2022, Venice, Italy