CFD simulations have been performed to study the flow over Triply Periodic Minimal Surfaces (TPMS) and presence of steady self-sustained periodic oscillations. The P-surface geometry is considered. Unsteady state laminar Simulations with PISO algorithm are initially performed over a 2D geometry and presence of the steady self-sustained periodic oscillations and heat transfer augmentation were established. Similar simulations on 3D P-surface geometry show that such oscillations are absent for this geometry, but a Nusselt number 3 times that of the flow between parallel plates can be obtained with the chaotic fluctuations that set up.