A smooth two-pass internal gas turbine cooling channel is numerically investigated. Transient conjugated non-rotating and rotating URANS simulations are executed. The transient thermochromic liquid crystal (TLC) approach is supported with these simulations as the temporally changing rotational buoyancy effects can be examined. The Reynolds number is 25,000, the rotation number is 0.24 and the initial buoyancy number is 0.63 (according to an inlet-to-wall density ratio of 0.23). As heat is transferred, the temperatures and heat fluxes change with increasing time, and so do the local buoyancy effects. The computational results are evaluated as averaged segmental values. They are compared to the experimental results from literature that have been determined for constant wall temperature experiments (various experimental runs with different constant wall temperatures). Especially in the first passage, there is a good agreement between the numerically gained results and the experimental data. The more complex flow inside the bend leads to more diverse characteristics and the second passage is only slightly effected.