
Instant Volume Flow
Concept 
The definition of the volume flow (J_V) is the volume element (\Delta V) over the time elapsed (\Delta t):
J_V =\displaystyle\frac{ \Delta V }{ \Delta t } |
which, in the limit of an infinitesimal time interval, corresponds to the derivative of the volume (V) with respect to the time (t):
J_V =\displaystyle\frac{ dV }{ dt } |
ID:(15718, 0)

Volume Flow and its Speed
Concept 
The volume (V) for a tube with constant the section Tube (S) and a position (s) is
V = s S |
If the section Tube (S) is constant, the temporal derivative will be
\displaystyle\frac{dV}{dt} = S\displaystyle\frac{ds}{dt}
thus, with the volume flow (J_V) defined by
J_V =\displaystyle\frac{ dV }{ dt } |
and with the flux density (j_s) associated with the position (s) via
j_s =\displaystyle\frac{ ds }{ dt } |
it is concluded that
J_V = S j_s |
ID:(15717, 0)

Flow for inhomogeneous flux density
Concept 
In the case that the flux density (j_s) is constant, the volume flow (J_V) can be calculated using the section or Area (S) according to:
J_V = S j_s |
If the flux density (j_s) varies, sufficiently small sectional elements dS can be considered so that the equation remains valid in the sense that the contribution to flow is:
dJ_V = j_s dS
Integrating this expression over the entire section results in
J_V =\displaystyle\int j_s dS |
ID:(15719, 0)

Model
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Parameters

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Calculations




Calculations
Calculations







Equations
j_s =\displaystyle\frac{ ds }{ dt }
j_s = @DIFF( s , t , 1 )
J_V =\displaystyle\frac{ dV }{ dt }
J_V = @DIFF( V , t , 1 )
J_V =\displaystyle\int j_s dS
J_V = @INT( j_s , S )
J_V = S j_s
J_V = S * j_s
V = s S
V = h * S
ID:(15714, 0)

Instant Volume Flow
Equation 
The volume flow (J_V) corresponds to the quantity volume (V) that flows through the channel during a time (t). Therefore, we have:
![]() |
The definition of the volume flow (J_V) is the volume element (\Delta V) over the time elapsed (\Delta t):
J_V =\displaystyle\frac{ \Delta V }{ \Delta t } |
which, in the limit of an infinitesimal time interval, corresponds to the derivative of the volume (V) with respect to the time (t):
J_V =\displaystyle\frac{ dV }{ dt } |
ID:(12713, 0)

Element volume
Equation 
The volume (V) is calculated by multiplying the section Tube (S) with the position (s) along the tube:
![]() |
![]() |
ID:(4876, 0)

Instantaneous flux density
Equation 
The flux density (j_s) is related to the position (s), which is the fluid position at the time (t), through the following equation:
![]() |
ID:(12714, 0)

Volume Flow and its Speed
Equation 
A flux density (j_s) can be expressed in terms of the volume flow (J_V) using the section or Area (S) through the following formula:
![]() |
The volume (V) for a tube with constant the section Tube (S) and a position (s) is
V = s S |
If the section Tube (S) is constant, the temporal derivative will be
\displaystyle\frac{dV}{dt} = S\displaystyle\frac{ds}{dt}
thus, with the volume flow (J_V) defined by
J_V =\displaystyle\frac{ dV }{ dt } |
and with the flux density (j_s) associated with the position (s) via
j_s =\displaystyle\frac{ ds }{ dt } |
it is concluded that
J_V = S j_s |
ID:(15716, 0)

Flow for inhomogeneous flux density
Equation 
If the flux density (j_s) is not constant and varies across the flow tube section the volume flow (J_V), it is calculated as the integral over that section:
![]() |
In the case that the flux density (j_s) is constant, the volume flow (J_V) can be calculated using the section or Area (S) according to:
J_V = S j_s |
If the flux density (j_s) varies, sufficiently small sectional elements dS can be considered so that the equation remains valid in the sense that the contribution to flow is:
dJ_V = j_s dS
Integrating this expression over the entire section results in
J_V =\displaystyle\int j_s dS |
ID:(15712, 0)