The capillary rise of liquid in the gap between two closely spaced parallel cylinders, whose radii may be identical or different, is modelled in this paper. On the basis of the minimum free energy principle and interfacial analysis, the vertical capillary rise of liquid at equilibrium was calculated as a function of distance of separation of the two cylinders. In order to validate our theory, a piece of experimental apparatus was designed and a series of experiments was conducted on it. Compared with the experimental data, our theoretical model gave a reasonably accurate prediction within experimental error except at a small separation of cylinders. Possible experimental errors were discussed. We also showed that the wicking height at equilibrium was nonlinear to the reciprocal of the hydraulic radius.

A finite-element deterministic two-dimensional thermal elasto-plastic contact model is presented in this article, which facilitates the investigation of the influence of steady-state frictional heating on contacting asperities and subsurface stress fields. This model takes into account the asperity distortion caused by the temperature variation in a tribological process, microplastic flow of surface asperities, and coupled thermo-elasto-plastic behaviour of the material, with and without considering the strain-hardening property of the material. The model is verified through the contact analysis of a rigid, isothermal cylinder with a thermally conductive, elasto-plastic plane. The maximum contact pressures increase with frictional heating. Furthermore, thermal effects on the contact pressure, real area of the contact, and average gap of a real rough surface with different frictional heat inputs under thermal elasto-plastic contact conditions are numerically investigated. It indicates that neglecting thermal effect overestimates the real area of the contact and underestimates the average gap between the contacting surfaces.