The Nonisothermal Flow interfaces combine the heat equation with flow equations in a Fluid domain. The advantage of using the multiphysics interfaces is that predefined couplings are available in both directions. In particular, the physics interfaces use the same definition of the density, which can therefore be a function of both pressure and temperature. Solving this coupled system of equations usually requires numerical stabilization accounting for the couplings, which the predefined multiphysics interfaces also set up.