A numerical procedure to predict the effects of gaseous cavitation in moderately to heavily loaded bearings is developed. The method is an outgrowth of the Elrod algorithm which is simple to w e a d which automatically implements cavitation bounda~y conditions at film rupture and refonnation. The current procedure makes w e of type dqferencing in the shear induced pow formulatioi~ to automatically switch from central to upwizd dfferences, and vice versa, at cavitation boundaries. Comparison is made with the results obtained w i n g Elrod's algorithm for variou~ test cases involving both slider and journal bearings.

In this paper, an implicit numerical scheme, based on an approximate factorization technique, is applied to a cavitation algorithm. The algorithm is a modified version of the Elrod cavitation algorithm, which automatically predicts film rupture and reformation in bearings. At each time step, Newton iterations are performed to achieve time accurate solutions for unsteady problems. This numerical scheme is applied in both orthogonal and nonorthogonal grid arrangements. An aligned finite grooved bearing and a flared, misaligned line grooved bearing are analyzed using this new approach. The predictions are compared with the results obtained with procedures currently being used. The new scheme is robust, quickly convergent, and provides time accurate solutions with a minimum expenditure of CPU time.

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The dynamics of hydrogen atoms in the hydrogen bonds of benzoic acid dimers have been studied as a function of hydrostatic pressure to pressures in excess of 4 kbar. This paper is primarily concerned with results up to 3.3 kbar. The temperature dependence of the correlation time for the motion at a series of pressures has been investigated using measurements of the proton spin–lattice relaxation time. Strong non-Arrhenius behavior is exhibited and the data are in good agreement with a model which invokes phonon assisted tunneling at low temperature and thermally activated Arrhenius dynamics at high temperature. The parameters in the model include the asymmetry of the double minimum potential experienced by the hydrogen atoms and dynamical variables relating to the tunneling and hopping processes. The rate of phonon assisted tunneling is observed to increase exponentially with increasing pressure and this is attributed to the increase in the tunneling matrix element which occurs as the distance between the potential wells is decreased and the overlap of the localized eigenstates beneath the barrier increases. We also observe a decrease in the asymmetry of the potential with increasing pressure which is attributable to modifications to the interdimer contributions to the potential. There is evidence in the nuclear magnetic resonance (NMR) data for two phase transitions below 4 kbar and one of these may be correlated with the reduction in asymmetry of the potential.

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