Friction friction and wear in so-called self-lubricating materials. Fluid friction occurs between fluid layers that are moving relative to each other. This internal resistance to flow is named "viscosity". In everyday terms, the viscosity of a fluid is described as its "thickness". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. The less viscous the fluid, the greater its ease of deformation or movement. All real fluids (except superfluids) offer some resistance to shearing and therefore are viscous. For teaching and explanatory purposes it is helpful to use the concept of an inviscid fluid
Flow computer be audited if modified, the reports which the system will be capable of producing and the methodologies to follow. Algorithms one can expect to see implemented in a typical gas flow computer are AGA Report No. 3, AGA Report No. 7, AGA Report No. 8 in the U.S. market. Internationally, ISO 5167-1:2003 and other ISO gas standard equivalents are in widespread use. Additional to natural gas, some flow computers offer an array of density calculations for steam, oxygen, hydrogen, nitrogen, and ethylene. Complex algorithms and Equations of State for wide ranges of hydrocarbon fluids and petrochemicals can also be found