Effect of a polymer additive on heat transport in turbulent Rayleigh-B\'enard convection

Measurements of heat transport, as expressed by the Nusselt number $Nu$, are reported for turbulent Rayleigh-B\'enard convection of water containing up to 120 ppm by weight of poly-[ethylene oxide] with a molecular weight of $4\times10^6$ g/mole. Over the Rayleigh number range $ 5\times 10^9 \alt Ra \alt 7 \times 10^{10}$ $Nu$ is smaller than it is for pure water by up to 10%.