Application of the LBM with adaptive grid on water hammer simulation

Abstract

A lattice Boltzmann method (LBM) is utilized to solve single-phase transient flow in pipes. In order to eliminate grid limitation related to the method of characteristics, governing equations are modified using appropriate coordinate transformation. The introduced modification removes connection between Courant number and spatial disposition of the computational nodes, forming a more flexible and robust mathematical base for numerical simulations. The computational grid is configured independently of the wave speed, significantly decreasing the demand for computational resources and maintaining the required accuracy of the method. Thereafter, the appropriate equilibrium distribution function for the D1Q3 lattice has been defined. In order to give a comprehensive base for modeling transient flow in complex pipeline systems, detailed elaboration of the corresponding boundary conditions has been given. Two benchmark problems with the corresponding error analysis are used to validate the proposed procedure.