Lesage et al. [25] showed for a fixed flow rate with varying thermal input conditions that the panel’s geometry created secondary flows in directions non parallel to the major axial flow thereby preventing the formation of a fully developed inner pipe flow and increasing the radial temperature gradient. This phenomenon is known as the field synergy principal in which thermal enhancement is attributed to a local alignment of the temperature and velocity fields (e.g., [26e29]). It consequently increases the heat flux at the periphery of the flow channel providing an improved heat source on the hot side of the embedded modules and an improved heat sink on their cold side.