The discussion explores the application of the continuity equation in air flow, particularly in the context of a frictionless air duct with varying dimensions. Participants examine whether the flow rate remains constant at all points along the duct under specific conditions.
Participants express differing views on the characterization of fluid mechanics equations and the conditions under which air flow can be treated as incompressible. There is no consensus on the definitions and implications of these equations.
The discussion includes assumptions about flow conditions, such as velocity thresholds for incompressibility, and the implications of friction losses, which remain unresolved.
Perfectly answered, thank you.SteamKing said:The mass of air into a duct must equal mass of air flowing out of the duct. What happens in between depends on friction losses, velocity of the air, etc. Gas dynamics is the discipline to study, especially if compressibility effects are suspected of occurring. If the flow velocity is below about 0.3M, then the air flow can be treated as incompressible and treated with the regular equations of fluid mechanics.