On the applicability of the EDAC method to non-Oberbeck–Boussinesq regimes in buoyancy-driven flows

Abstract

This work presents an extension of the Entropically Damped Artificial Compressibility (EDAC) method to simulate buoyancy-driven flows under Non-Oberbeck–Boussinesq (NOB) conditions, characterized by strong thermophysical property variations. By integrating realistic data from the National Institute of Standards and Technology (NIST) database, the formulation accounts for temperature-dependent density and transport coefficients. A sixth-order compact finite-difference scheme with high-order filtering and Runge–Kutta time integration is used to solve the equations in a Rayleigh–Benard convection configuration for air, water, and steam. Diagnostic quantities such as the central temperature shift, relative Nusselt number, and RMS velocity divergence confirm agreement with existing literature. Despite not enforcing incompressibility explicitly, the method exhibits low divergence errors, even in high density gradient cases like steam. These results demonstrate the accuracy and robustness of EDAC for NOB flows, offering a viable alternative to traditional pressure Poisson solvers.