AbstractIn this paper a method is described to simulate isobaric multiphase flows at low Mach numbers with steep temperature gradients for fluids with non‐negligible thermal expansivity. Governing equations and solution procedure are outlined. Further, a test case is shown in order to verify the model. Single phase natural convection flows with large temperature differences and either constant or temperature dependent transport properties were simulated to prove the solution of coupled Navier‐Stokes and energy equations. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)