  This work investigates spanwise wall oscillation (SWO) as a method to
preferentially enhance heat transfer over drag in turbulent channel flow.
Direct numerical simulations at $Re_\tau=180$ and $\Pr=1$ show set of
wall-oscillation parameters reducing drag also decrease heat transfer
similarly, maintaining coupled transport. However, large period ($T^+=500$) and
amplitude ($W^+=30$) induce substantially greater heat transfer
intensification, increasing 15 % versus only 7.7 % drag rise. This Reynolds
analogy breaking enables preferential elevation of heat transport over
momentum. FIK identity analysis reveals negligible impact of forcing terms on
dissimilarity. Instead, differences arise from the solenoidal velocity and
linear temperature equations. Both the turbulent shear stress and heat flux are
amplified near the wall under oscillation. However, the heat flux intensifies
more substantially, especially at its peak. This preferential enhancement of
the near-wall heat flux, exceeding the shear stress amplification, facilitates
greater thermal transport augmentation relative to the friction increase.
Results demonstrate that spanwise wall oscillation can preferentially intensify
heat transfer beyond drag, providing a promising technique for improving heat
exchanger. Further work should optimize the period and amplitude of the
oscillation and elucidate the underlying physics of this dissimilar heat
transfer control.
