Volume-of-fluid based two-phase flow methods on structured multiblock and overset grids

A geometric volume-of-fluid (VOF) method is implemented on the static/dynamic overset grids with a new VOF interpolation algorithm developed. The VOF value cannot be directly interpolated through the overset grid boundaries since the VOF function is a discontinuous step function. In the present study, the interface is reconstructed in the fringe cells of the overset grids using the interpolated distance function and normal vector. The VOF value in the fringe cells is calculated geometrically based on the reconstructed interface on the physical domain. The gravity and surface tension forces are implemented using a VOF based ghost fluid method, where a ghost pressure interpolation scheme is developed to handle the pressure jump across the interface due to the density changes and surface tension effect. Numerical tests and application examples have been performed for the verification and validation of the numerical methods developed in the present study. The advection tests show that the effect of the VOF overset interpolation on the accuracy of the VOF method is small. The numerical test for the static pressure shows that the present VOF based ghost fluid method can greatly reduce the spurious velocity observed in the body force method. The sharp pressure profile due to the surface tension effects can be preserved across the interface. Application examples demonstrate the capability and superiority of the VOF based numerical methods for the prediction of the violent ship flows involving strong air water interface interactions and complex geometries.

Automated summary

A geometric VOF method is implemented on static/dynamic overset grids using a new VOF interpolation algorithm. The interface is reconstructed in the fringe cells of the overset grids, and the VOF value is calculated based on the reconstructed interface. Gravity and surface tension forces are implemented using a VOF based ghost fluid method. Numerical tests and application examples demonstrate the capability and superiority of the VOF based numerical methods for predicting violent ship flows.