Three-dimensional simulations of liquid waves in isothermal vertical churn flow with OpenFOAM
- 38 Downloads
Periodic liquid waves of large amplitude are one of characteristic phenomena observed in the churn flow regime of gas–liquid flow in vertical conduits, where the liquid flowing on the wall is entrained upwards by the gas flow in the core. The present work investigates the frequency of these large liquid waves. Three-dimensional simulations of isothermal churn flow of air and water in 19 and 32 mm vertical pipes were performed using the interFoam solver from the OpenFOAM library. Turbulent features in the flow are modelled using the unsteady Reynolds Averaged Navier–Stokes approach with the k–ω SST (shear stress transport) model. Interface sharpening with bounded compression was used to preserve the sharpness of gas–liquid interface by compensating the diffusive fluxes of the numerical scheme. A sensitivity study on the global amount of interface compression was performed for two flow cases taken from the literature. Mesh sensitivity study was performed using four meshes, ranging from a coarse mesh with several hundred thousand cells, to a fine mesh with several million computational cells. Results for the calculated wave frequency and wave maximum amplitude agree with measured values reported in the literature.
Keywordstwo-phase flow simulation vertical churn flow wave frequency interface compression
The authors acknowledge the financial support from the Slovenian Research Agency (research core funding No. P2-0026 “Reactor engineering”).
- Noh, W. F., Woodward, P. 1976. SLIC (simple line interface calculation). In: Proceedings of the 5th International Conference on Numerical Methods in Fluid Dynamics, 330–340.Google Scholar
- OpenCFD Ltd. 2015. OpenFOAM: The open source CFD toolbox. Available at http://www.openfoam.com/.
- Rusche, H. 2002. Computational fluid dynamics of dispersed two-phase flows at high phase fraction. Ph.D. Thesis. Imperial College of Science, Technology and Medicine, UK.Google Scholar
- Tekavcic, M., Koncar, B., Kljenak, I. 2018b. The effect of interface compression on the simulated frequency of liquid waves in vertical churn flow. In: Proceedings of the 27th International Conference Nuclear Energy for New Europe.Google Scholar
- Ubbink, O. 1997. Numerical prediction of two fluid systems with sharp interfaces. Ph.D. Thesis. Imperial College of Science, Technology and Medicine, UK.Google Scholar
- Vierow, K. 2008. Countercurrent flow limitation experiments and modeling for improved reactor safety. Technical Report. Texas A&M University, Texas, USA.Google Scholar
- Youngs, D. L. 1982. Time-dependent multi-material flow with large fluid distortion. Numerical Methods for Fluid Dynamics, 273–285.Google Scholar