Computational fluid dynamics (CFD) has been unable to reliably predict aeration and drag torque in clutches. In this study, a CFD method was developed to reliably predict the onset of aeration and drag torque as a function of the clutch's rotational speed. This study showed that though the oil and air behave as if they are incompressible at steady-state, the formulation must account for the compressible nature of the gas and the unsteady processes that occur before reaching steady-state. This study also showed that the dynamic nature of the contact angle between the oil and the stationary disk must be accounted for to predict drag torque and aeration as a function of rotational speed, and a model of the dynamic-contact angle was developed.

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