Influence of spanwise domain constraint on flow statistics and heat transfer in spanwise rotating plane Poiseuille flows

The influence of the spanwise computational domain constraint on flow statistics and heat transfer is investigated in spanwise rotating plane Poiseuille flow (RPPF) through direct numerical simulations at a fixed global friction Reynolds number of Reτ=180. Simulations are conducted at rotation numbers Roτ=5 and 10, with the spanwise computational domain size Lz varying within {2π,π,0.36π,0.25π,0.18π}. In addition to the linear behaviors of the mean streamwise velocity, Reynolds shear stress, and mean temperature observed near the pressure side, a second linear region in the mean temperature is identified near the suction wall for cases with Lz≤0.36π, signifying a flow laminarization. To support the observations, the interscale transport of turbulent kinetic energy and cluster analysis are performed, compensating the former argument of contractions in roll-cell structures. The results reveal that when Lz≤0.36π, the large-scale inverse energy cascades vanish, and the strength and height of cluster patterns are significantly altered, resulting in a reduction in heat transfer efficiency. Therefore, it is recommended to avoid using an excessively small spanwise computational domain when simulating flow and heat transfer problems in RPPF.