Hamiltonian Transformation to Compute Thermo-osmotic Forces.


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Authors
Ganti, Raman 
Liu, Yawei 
Abstract

If a thermal gradient is applied along a fluid-solid interface, the fluid experiences a thermo-osmotic force. In the steady state, this force is balanced by the gradient of the shear stress. Surprisingly, there appears to be no unique microscopic expression that can be used for computing the magnitude of the thermo-osmotic force. Here we report how, by treating the mass M of the fluid particles as a tensor in the Hamiltonian, we can eliminate the balancing shear force in a nonequilibrium simulation and therefore compute the thermo-osmotic force at simple solid-fluid interfaces. We compare the nonequilibrium force measurement with estimates of the thermo-osmotic force based on computing gradients of the stress tensor. We find that the thermo-osmotic force as measured in our simulations cannot be derived from the most common microscopic definitions of the stress tensor.

Description
Keywords
0915 Interdisciplinary Engineering
Journal Title
Phys Rev Lett
Conference Name
Journal ISSN
0031-9007
1079-7114
Volume Title
121
Publisher
American Physical Society (APS)
Sponsorship
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (674979)