Thermal issues become serious bottlenecks for high-end and mobile ICs as well. To analyse the temperature dependent behaviour, functional-thermal co-simulation can be performed. We are developing a framework called LogiTherm which can be used to perform such simulation of digital and mixed signal circuits on different abstraction levels. The framework utilizes the so-called simulator coupling technique to connect the thermal and functional domain. Multiple thermal simulator engines are integrated into our system (e.g. 3D-ICE, HotSpot, SUNRED), but their implementation is not efficient on modern computer architectures, thus the simulation speed can be limited. In this paper, we describe a new thermal model and a simulator engine designed for multicore processors and GPUs to enable more detailed simulation. A new, adaptive co-simulation strategy is also described, which can further reduce the computational overhead of the thermal simulations.