Natural convective heat transfer of water near its density maximum in an eccentric horizontal annulus

► Natural convective heat transfer of water near its density maximum in a horizontal annulus. ► Transition of the flow pattern with the Rayleigh number and the eccentricity. ► Appearing mechanism of the Rayleigh-Bénard cells. ► Effect of the eccentricity on the average Nusselt number in horizontal concentric annulus.