LocalResistance

Local Resistance

    LocalResistance

Library

HydraulicsByFluidon/Components/Resistors

Description

The component LocalResistance is a model of a flow resistance that represents the local pressure loss, which is typically calculated with the Pressure loss coefficient zeta.

Diameter is used for calculation of flow velocity v.

Values of Pressure loss coefficient can be found in literature, e. g. in I.E. Idelchik, Handbook of Hydraulic Resistance.

In the following tables standard values for the resistance coefficient Zeta are given. It is distinguished between bends (without marked radius of curvature R) and elbows (with considerable radius of curvature R), circular cross-sections are always assumed:

Bend

For bends with distinct radius of curvature R the resistance coefficient Zeta changes depending on the angle of curvature phi according to the formula:

From the first table the values for Zeta 90deg depending on the ratio radius of curvature R to tube diameter d can be taken. The second table specifies values for the factor k depending on the angle of curvature phi (where appropriate interpolation is necessary).

At multiple bends, the following equations can give clues for the calculation of Zeta:

Double bend (two bends arranged semicircular):

Room crooked (two bends arranged angular to each other):

Floor crooked (two bends arranged s-shaped):

Elbow

For bends without marked radius of curvature R, Zeta can be taken out of the following table and/or can be computed by interpolation:

Parameters

LocalResistance_0

NameLabelDescriptionData TypeValid Values

mo_Zeta

Zeta

Pressure loss coefficient

Scalar

mo_D

D

Diameter

Scalar

mo_InputMax

InputMax

Scalar

mo_dp

dp

dp

Structure

mo_dp/fixed

fixed

Cell of scalars

true
false

mo_dp/start

start

Cell of scalars

LocalResistance_1

NameLabelDescriptionData TypeValid Values

mo_forwardFluidProperties

forwardFluidProperties

Forward fluid properties between ports

Scalar

true
false

LocalResistance_2

NameLabelDescriptionData TypeValid Values

mo__nmodifiers

Number of Modifiers

Specifies the number of modifiers

Number

mo__modifiers

Modifiers

Add new modifier

Structure

mo__modifiers/varname

Variable name

Cell of strings

'volumeFlowA'
'volumeFlowB'
'fluidId'
'A'
'signDp'
'pMax'

mo__modifiers/attribute

Attribute

Cell of strings

'start'
'fixed'

mo__modifiers/value

Value

Ports

NameTypeDescriptionIO TypeNumber

fluidPortA

implicit

Hydraulic port A

input

1

fluidPortB

implicit

Hydraulic port B

input

2

See Also