Two way coupled fields multi-physics modeling is investigated as an additional approach to address out-of-plane FEI. It is established in the literature that to model the damping-controlled fluid elastic instability, a finite time delay between tube vibration and fluid perturbation must be realized. The phase lag between tube vibration and flow perturbation due to damping must be adequately captured by the model. The effects of tube frequency, turbulence level, location, and mean gap velocity on the relative phase values must also be captured. This approach will allow the time delay between tube vibration and flow perturbation due to damping, as well as turbulence, and stiffness to be intrinsically modeled. We will introduce the applicability of the method to in-plane FEI in a future paper once we have based lined it against out of plane FEI empirical results.