An improved decoupling algorithm for low Mach number near-critical fluids

- An improved iterative algorithm is proposed for solving near-critical fluid flows.
- Pressure-velocity coupling is treated through block-coupled method.
- Energy equation written in terms of the specific heat at constant pressure is used.
- The proposed algorithm has a better stability and can reduce the CPU time.

This paper describes an improved decoupling algorithm for calculating low Mach number near-critical fluid flows, in which the cp-formulation of the energy equation is used (cp refers to the specific heat at constant pressure) and the pressure-velocity coupling is treated through the block-coupled method, together with a transformation of the continuity equation. The algorithm is validated by a 2D near-critical CO2 Rayleigh-Bénard convection problem. After the mesh and time step independence studies, the correctness is presented through the stability behaviors of the hot boundary layer under different heating intensities and the typical evolution of the temperature field. The improved decoupling algorithm owns a better stability and can further reduce the CPU time. The advantages are even more obvious when the flow is convection-dominated.