Flow Processes Depending on the Pressure

If we intend to investigate the influence of pressure on the deformation and the relaxation effects, we must replace At/ with Uov. This is a very rough approximation connected with the 6—12 potential (Cj, C2 and C3 are empirical constants, Ap the pressure increase). The relaxation time will then be 

All relaxation and diffusion processes depend on pressure. The viscosity rj also increases in an exponential manner 

It is important to note that with increasing pressure the free volume and a decrease. In this way the relaxation time and the viscosity are influenced by pressure to a far greater degree than is calculated using Eqs. (37 a) and (48a)53  

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