Thermal rectification features: a study starting from local assumptions

In the present work, addressing the investigation of thermal rectification in asymmetric models (in particular, graded systems), we generalize a previously developed approach based on the features of the local thermal conductivities. We study the behavior of the predicted rectification as the gradient of temperature into the system increases, and, considering a small chain, we give indications of a big rectification factor in very asymmetric models, a result which makes these graded materials genuine candidates for the construction of thermal diodes. Moreover, our results allow us to understand the details which determine the direction of the bigger heat flow. (paper)