Figures 5(a) and 5(b) are the non-dimensional temperature contours for the two cases. It is to be noted that the non-dimensionalisation of temperature is such that red zone indicates cold fluid and blue zone corresponds to hot fluid. For the stationary case, the incoming coolant fluid is distributed almost symmetrically between the two walls. For the rotational case, the temperature of the bulk fluid becomes asymmetric because high momentum cold fluid is pushed towards the trailing side by the Coriolis-induced secondary flows. Thus, for the stationary case, both walls and the experience fluid of comparable temperature, while for the rotational case, the rib as well as wall on the trailing side are exposed to colder fluid compared to its counterparts in the leading side. Thus the heat transfer on the trailing surface is expected to be higher. Due to the shedding of the vortices from the ribs (see Figure 4) there is continuous breakdown of thermal boundary layers on both the walls. The recirculatory regions (represented by the high temperature zones) behind the ribs are almost of equal size for the non-rotating case whereas they are of different sizes for the rotational case. It is already mentioned that the presence of ribs produces large scale unsteadiness. Due to large scale irregular flow separation and reattachment locally, there is higher rate of heat removal from the heated walls and this results in enhanced heat transfer rate compared to their smooth wall counterparts.

Currently two papers are in preparation, and the results will be presented in detail in the upcoming contractors meeting in February.

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