.Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumber .Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumberCalculation of Reynolds Number
Re = |v|ρD/μ
a measure of the relationship between inertial forces (vρ) and viscous forces (D/μ).
The following table gives examples for the characteristic dimension D and the velocity v for different fluid flow devices:
| Device Type | Characteristic Dimension D | Velocity v |
|---|---|---|
| Circular Pipe | diameter | m_flow/ρ/crossArea |
| Rectangular Duct | 4*crossArea/perimeter | m_flow/ρ/crossArea |
| Wide Duct | distance between narrow, parallel walls | m_flow/ρ/crossArea |
| Packed Bed | diameterOfSpericalParticles/(1-fluidFractionOfTotalVolume) | m_flow/ρ/crossArea (without particles) |
| Device with rotating agitator | diameterOfRotor | RotationalSpeed*diameterOfRotor |
function ReynoldsNumber extends Modelica.Icons.Function; input SI.Velocity v "Mean velocity of fluid flow"; input SI.Density rho "Fluid density"; input SI.DynamicViscosity mu "Dynamic (absolute) viscosity"; input SI.Length D "Characteristic dimension (hydraulic diameter of pipes)"; output SI.ReynoldsNumber Re "Reynolds number"; end ReynoldsNumber;