Numerical Simulation and Experimental Validation of Three-Dimensional Unsteady Multi-Phase Flow in Flushing Process of Toilets

Abstract:

In order to predict the flush performances of digital toilet products before mass production, a numerical simulation for a three-dimensional unsteady multi-phase flow in the flushing process of a wash-down toilet is carried out by using FLUENT software. The finite volume method (FVM) is used to discrete the three governing equations in space and time. The discrete equations are solved by using the first-order upwind discretization scheme and the PISO pressure-velocity coupling scheme. The realizable turbulence model is chosen as the viscous model to treat the fluid flow with large bending curvature wall. The volume of fluid (VOF) model is applied to solve the transient free-surface problem. First, a two-phase flow was simulated on the assumption that there is not sewage but water in the trap seal. Then, by simplifying the mixture of sewage and water in the trap seal as the third phase with high viscosity, a three-phase flow was simulated. Moreover, in order to validate the simulated results, a flushing testing was conducted to test the flush range, and a target type flow meter was designed, calibrated and applied to test the flush velocity. The comparisons show a good agreement between the numerical and experimental results. Based on the verified simulation results, the flush performances of the digital wash-down toilet, such as flush range, flush velocity and sewage replacement ability, can be predicted and evaluated.

• Periodical: Applied Mechanics and Materials (Volumes 444-445)
• Pages: 304-311
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.444-445.304
• Online since: October 2013
• Authors: Jian Guo Hu, You Song Sun, Zheng Rong Zhang
• Keywords: Experimental Validation, Flushing Process, Multiphase Flow, Numerical Simulation, Toilet

References

[1] ZR Zhang, YS Sun, XT Pan and YH Xu. Rapid Manufacturing Technology of Complicated Ceramics Based on CAD/CAE/CAM/RP. China Ceramics, 2005, 41(5): 35-38.

[2] ZR Zhang, YS Sun, XT Xiao and ZG Ma. Sanitary Ceramic Products CAD System Based on Application Development of Unigraphics. Journal of Computer-Aided Design & Computer Graphics, 2007, 19(6): 764-768.

[3] ZJ Liu, J Ouyang, SC Deng and Xin Liu. The Application Prospects and Topics of Sanitary Product Digital Technology. Ceramics, 2010, (11): 11-15.

[4] SC Deng, ZJ Liu, J Ouyang and X Liu. Research on the Digital Design and Manufacture Process and Key Technologies of Ceramic Sanitary Ware. China Ceramics, 2011, 43(3): 56-60.

[5] J Xia, XM Yin, MS Lin, et al. Research on the Key Technology and Method of CAD for Sanitary Products. Journal of Sichuan University (Engineering Science Edition), 2001, (1): 93-95.

[6] L Ma, PQ Liu, JJ Nin (2004). A Hydraulic Model for the Water-rinsing Process of Siphonage-toilet. Journal of Hydrodynamics, Ser. A. 19(6): 783-787.

[7] JB Li, ZJ Liu, SY Zhao. Acoustic Analysis of Improvement on Toilet's Siphon. Noise and Vibration Control, 2007, (3): 123-126.

[8] XT Pan, YS Sun, JM Zhan and J Li. The Determinant Method of Ceramic Sanitary Ware Forming Siphon Phenomenon Based on VOF Model. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2007, 46(4): 36-40.

[9] MF Liu, XT Pan. Three-Phase Flow Analysis for Siphon Jet Toilet Based on VOF Model. China Ceramics, 2011, 47(11): 69-73.

[10] SY Zhao, ZJ Liu, ZW Peng. Optimized Design of the Toilet Siphon Pipeline Based on CFD Flow field Analysis. Mechanics in Engineering, 2007, 29(4): 33-36.

[11] SY Zhao, ZJ Liu, ZW Peng. Optimized Design of Toilet Siphon Pipeline Based on Fluent and Its Validated Test. Journal of System Simulation, 2008, 20(16): 4412-4416.

[12] ZW Peng, ZJ Liu, DL Huang. Study of Water Saving and Wastewater Minimization Technology Based on Computational Fluid Dynamics. Technology of Water Treatment, 2008, 35(8): 72-75.

[13] ZH Ge, JS Wang, PG Su and JB Liang (2009). The structure optimization of the siphonic bedpan's flow channel based on the numerical simulation technology. ICICTA 2009, 2009, (10): 360-363.