The pressure-viscosity coefficient for Newtonian EHL film thickness with general piezoviscous response

There has been a long-standing need for a piezoviscous parameter α_film that, together with the ambient viscosity μ₀, will completely quantify the Newtonian rheology so that the film thickness for liquids that do not shear-thin in the inlet may be calculated as h =h(μ₀, α_film,...), regardless of the details of the pressure-viscosity response. It seems that Blok's reciprocal asymptotic isoviscous pressure has certain advantages over the conventional pressure-viscosity coefficient, which is poorly suited for this purpose. The first detailed review of piezoviscous models for low pressures is provided. A simulation code that is apparently stable for all realistic pressure-viscosity response was utilized with diverse piezoviscous models and model liquids to develop a satisfactory definition of α_film that reads α_film=[1-exp(-3)]/[∫₀^3/α * μ(0)dp/μ(p)]; 1/α*= ∫₀^∞μ(0)dp/μ(p). In the case of μ=μ₀ exp(αp), α_film = α and formulas are provided for other models.