Tracer diffusion under heat and momentum transport for general repulsive potentials

Tracer diffusion in a steady state with both velocity and temperature gradients is analyzed. The results are obtained from a kinetic model that incorporates a temperature dependence in the collision frequencies. This allows for the consideration of general r−1-repulsive interactions. An explicit expression of the tracer diffusion tensor is obtained in terms of the shear rate, the mass ratio, the force constant ratio and a parameter characterizing the interaction model considered. This expression extends previous results derived in the case of Maxwell molecules (l = 5).