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

There has been a long-standing need for a piezoviscous parameter alpha(film) that, together with the ambient viscosity mu(0), 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(mu(0), alpha(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 alpha(film) that reads alpha(film) =[1-exp(-3)]/[integral(3/alpha*)(0) mu(0)dp/mu(p)]; 1/alpha* = integral(infinity)(0) mu(0)dp/mu(p). In the case of mu = mu(0) exp(alpha p), alpha(film) = alpha and formulas are provided for other models.