The improvement of overall performance in power to mass ratio of modern gas turbines can greatly be contributed to the effective cooling of the turbine blades. Optimization of coolant performance is essential as the coolant flow introduces losses which need to be minimized. This paper introduces a new model to simulate heat transfer in ribbed channels. In the ribbed sections large variations in turbulence levels occure and the secondary flows associated with these ribs are responsible for significant local heat transfer variations. Furthermore, the ribs produce a complex flow structure so that there is continuing need for a better understanding of the flow physics in ribbed ducts. A finite difference simulation of the fluid flow and temperature distribution in the inlet section of the cooling channel of a typically cooled turbine blade is used to evaluate the new model. Various configurations of rib turbulators in the blade passages were simulated. In the case of the 45° angled ribs, there is a strong sideways secondary flow component which produces both increased overall heat transfer as well as asymmetrical local heat transfer enhancement. The results show the flow structure and heat transfer enhancement and correlate local heat transfer variations to secondary flow details. In general the predicted heat transfer rates compare well with measured data for 90° ribs, but further work needs to be done to accurately model angled ribs. NOMENCLATURE