Efficient approximate expression for unsteady pipe flow with high-viscosity fluid

摘要

An approximate first-order expression for modeling frequency-dependent friction of unsteady pipe flow with high-viscosity fluid has been developed with the method of nonlinear square integral optimum in the frequency domain. This simple expression of first-order lag elements is more accurate and efficient than others in both the frequency and domain domains and can be applied to calculations of both frequency and transient response of unsteady pipe flow for oil hydraulic systems.