The project is focused on the effects of thermal gradients in fluids and soft solids. On the theoretical side the planned activity is aimed at identifying the thermal forces which originate from the presence of temperature gradients in simple fluids confined in nano or micropores. This can be achieved by comparing numerical simulations with the predictions of a first principle theoretical analysis based on Linear Response Theory. From the experimental side, the project includes both the design and the realization of a novel apparatus to directly quantify the effects of thermal gradients on fluids confined in capillaries and the study of the effects of thermal gradients in soft solids.
The theoretical investigations were mainly carried out on a simplified model mimicking a liquid in a capillary joining two reservoirs at different temperatures: a two dimensional slab contained a Lennard-Jones fluid confined by an external potential and closed at the two ends by hard walls at different temperatures. The main theoretical achievement was the unambiguous identification of the excess of local virial enthalpy as the key equilibrium property driving the thermo-osmotic mechanism in the presence of a temperature gradient, as shown by the remarkable agreement between the theoretical prediction of the ensuing pressure gradient in the fluid and the results of non equilibrium numerical simulations.
The experimental activity was focused on the planning of a setup for measuring thermo-osmosis, including the actual design and implementation of a differential pressure setup, followed by extensive checks on the expected achievable accuracy and by its application to thermo-osmosis experiments in model fluids. The setup is now fully operational and the first run of experiments is under way.
The theoretical investigations were mainly carried out on a simplified model mimicking a liquid in a capillary joining two reservoirs at different temperatures: a two dimensional slab contained a Lennard-Jones fluid confined by an external potential and closed at the two ends by hard walls at different temperatures. The main theoretical achievement was the unambiguous identification of the excess of local virial enthalpy as the key equilibrium property driving the thermo-osmotic mechanism in the presence of a temperature gradient, as shown by the remarkable agreement between the theoretical prediction of the ensuing pressure gradient in the fluid and the results of non equilibrium numerical simulations.
The experimental activity was focused on the planning of a setup for measuring thermo-osmosis, including the actual design and implementation of a differential pressure setup, followed by extensive checks on the expected achievable accuracy and by its application to thermo-osmosis experiments in model fluids. The setup is now fully operational and the first run of experiments is under way.