Package Modelica.​Fluid.​Pipes.​BaseClasses.​CharacteristicNumbers
Functions to compute characteristic numbers

Information

Standard package icon.

Extends from Modelica.​Icons.​Package (Icon for standard packages).

Package Contents

NameDescription
NusseltNumberReturn Nusselt number
ReynoldsNumberReturn Reynolds number from v, rho, mu, D
ReynoldsNumber_m_flowReturn Reynolds number from m_flow, mu, D, A

Function Modelica.​Fluid.​Pipes.​BaseClasses.​CharacteristicNumbers.​ReynoldsNumber
Return Reynolds number from v, rho, mu, D

Information

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 TypeCharacteristic Dimension DVelocity v
Circular Pipediameter m_flow/ρ/crossArea
Rectangular Duct4*crossArea/perimeter m_flow/ρ/crossArea
Wide Ductdistance between narrow, parallel walls m_flow/ρ/crossArea
Packed BeddiameterOfSpericalParticles/(1-fluidFractionOfTotalVolume) m_flow/ρ/crossArea (without particles)
Device with rotating agitatordiameterOfRotor RotationalSpeed*diameterOfRotor

Extends from Modelica.​Icons.​Function (Icon for functions).

Inputs

TypeNameDescription
VelocityvMean velocity of fluid flow
DensityrhoFluid density
DynamicViscositymuDynamic (absolute) viscosity
LengthDCharacteristic dimension (hydraulic diameter of pipes)

Outputs

TypeNameDescription
ReynoldsNumberReReynolds number

Function Modelica.​Fluid.​Pipes.​BaseClasses.​CharacteristicNumbers.​ReynoldsNumber_m_flow
Return Reynolds number from m_flow, mu, D, A

Information

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*A
See also Pipes.BaseClasses.CharacteristicNumbers.ReynoldsNumber.

Extends from Modelica.​Icons.​Function (Icon for functions).

Inputs

TypeNameDescription
MassFlowRatem_flowMass flow rate
DynamicViscositymuDynamic viscosity
LengthDCharacteristic dimension (hydraulic diameter of pipes or orifices)
AreaACross sectional area of fluid flow

Outputs

TypeNameDescription
ReynoldsNumberReReynolds number

Function Modelica.​Fluid.​Pipes.​BaseClasses.​CharacteristicNumbers.​NusseltNumber
Return Nusselt number

Information

Extends from Modelica.​Icons.​Function (Icon for functions).

Inputs

TypeNameDescription
CoefficientOfHeatTransferalphaCoefficient of heat transfer
LengthDCharacteristic dimension
ThermalConductivitylambdaThermal conductivity

Outputs

TypeNameDescription
NusseltNumberNuNusselt number

Generated 2018-12-12 12:13:24 EST by MapleSim.