Viscosity and thermal diffusion and obstacle-fluid thermal-energy exchange

TYCHO calculates the influence of viscosity, if the corresponding switch is set in the parameterfile. The viscosity is derived in an explicit way, therfore the timestep calculation is altered to satisfy $dt < 0.5 \frac{dx^2}{\nu}$, where $\nu$ is the kinematic viscosity [m$^2$/s]. The kinematic viscosity is a function of the gas' temperature and approximated ba Sutherland's law in the temperature regime [200 < K < 1400]. Velocity-fluxes in the hydro-core are altered by terms $F = -\nu \nabla v$. Special emphasis is given in the seperation of the computational domain in obstacle and fluid parts. Note that the routine requires more memory due to the viscosity calculation.
Thermal diffusion in obstacles is calculated in an explicit operator-splitting way. The Heat transfer from the obstacle to the gas is realised by providing the code the specific heat-capacities for the gas and the obstacle. In the routine alpha_heat_transfer the heat-transfer coefficient between obstacle and gas is derived as a function of gas velocity at the boundary. Change this function to serve your problem best.