PERFORMANCE OF SHARP-VERSUS-DIFFUSE INTERFACE-BASED LEVEL SET METHOD ON A STAGGERED-VERSUS-CO-LOCATED GRID FOR CMFD

Abstract

The present work is on comparison of computational performance for various level set methods (LSMs): diffuse interface level set method on staggered grid (DI-LSM<sub>stag</sub>), sharp-interface level set method on staggered grid (SI-LSM<sub>stag</sub>), diffuse interface level set method on co-located grid (DI-LSM<sub>col</sub>), and sharp interface level set method on co-located grid (SI-LSM<sub>col</sub>). Even though the implementations of the diffuse and sharp interface (DI and SI) approaches on staggered grid are straightforward, an additional pressure-interfacial force balance needs to be ensured on the co-located grid. This is established here with balanced force method (BFM) for the DI-LSM and ghost fluid method (GFM) for the SI-LSM. Computational performances of these LSMs are presented for a variety of computational multi-fluid dynamics (CMFD) problems: static drop, dam break, rising bubble, falling droplet, and droplet coalescence. Greater accuracy is found with SI-LSMs for the static drop, dam break, and rising bubble, whereas for the other problems, both SI-LSM and DI-LSM result in almost the same accuracy. Smaller computational time is taken by the SI-LSM for rising bubble and falling droplet, and by DI-LSM for the dam break and droplet coalescence. Comparing between grid systems, co-located grid resulted in greater accuracy for all the problems except falling droplet, for which both grid systems resulted in similar accuracy, whereas, a smaller computational time is taken by the co-located grid for rising bubble and falling droplet, and by the staggered grid for dam break and droplet coalescence. Overall, SI-LSM on the co-located grid shows better results with a slight increase in computational time as compared to the other LSMs, and is a suitable alternative to the staggered grid.