dischargekoefficient
Discharge coefficient, abbreviated Cd, is a dimensionless factor used in fluid dynamics to quantify the loss of flow capacity when a fluid passes through a restriction such as an orifice, nozzle, or valve. It is defined as the ratio of the actual flow rate to the ideal flow rate under the same pressure drop. For incompressible, volumetric flow through a sharp-edged orifice, the relationship is often written as Q_actual = Cd × A × sqrt(2 × ΔP / ρ), where A is the cross-sectional area of the restriction, ΔP the pressure drop, and ρ the fluid density. The corresponding mass flow rate is m_dot = ρ × Q_actual.
Cd values are typically less than 1 and depend on geometry, flow regime, and fluid properties. Common
Several factors influence Cd, including the restriction’s geometry (such as beta ratio, the ratio of the restriction
Cd is a key parameter in flow metering and process control. It is used to convert measurable
---