Package Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbersFunctions to compute characteristic numbers
Package Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers
Standard package icon.
Extends from Modelica.Icons.Package (Icon for standard packages).
| Name | Description |
|---|---|
NusseltNumber | Return Nusselt number |
ReynoldsNumber | Return Reynolds number from v, rho, mu, D |
ReynoldsNumber_m_flow | Return Reynolds number from m_flow, mu, D, A |
Function Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumber
Calculation 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 |
Extends from Modelica.Icons.Function (Icon for functions).
| Type | Name | Description |
|---|---|---|
Velocity | v | Mean velocity of fluid flow |
Density | rho | Fluid density |
DynamicViscosity | mu | Dynamic (absolute) viscosity |
Length | D | Characteristic dimension (hydraulic diameter of pipes) |
| Type | Name | Description |
|---|---|---|
ReynoldsNumber | Re | Reynolds number |
Function Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumber_m_flow
Simplified calculation of Reynolds Number for flow through pipes or orifices;
using the mass flow rate m_flow instead of the velocity v to express inertial forces.
Re = |m_flow|*diameter/A/μ with m_flow = v*ρ*ASee also Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumber.
Extends from Modelica.Icons.Function (Icon for functions).
| Type | Name | Description |
|---|---|---|
MassFlowRate | m_flow | Mass flow rate |
DynamicViscosity | mu | Dynamic viscosity |
Length | D | Characteristic dimension (hydraulic diameter of pipes or orifices) |
Area | A | Cross sectional area of fluid flow |
| Type | Name | Description |
|---|---|---|
ReynoldsNumber | Re | Reynolds number |
Function Modelica.Fluid.Pipes.BaseClasses.CharacteristicNumbers.NusseltNumberNusselt number Nu = alpha*D/lambda
Extends from Modelica.Icons.Function (Icon for functions).
| Type | Name | Description |
|---|---|---|
CoefficientOfHeatTransfer | alpha | Coefficient of heat transfer |
Length | D | Characteristic dimension |
ThermalConductivity | lambda | Thermal conductivity |
| Type | Name | Description |
|---|---|---|
NusseltNumber | Nu | Nusselt number |