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Motivation


One of the key challenges in Pipe Flow Dynamics is to predict the pressure distribution along the pipe during the stationary fluid transport.

In many practical cases the stationary pressure distribution can be approximated by Isothermal or Quasi-isothermal homogenous fluid flow model.

Pipeline Flow Pressure Model is addressing this problem with account of the varying pipeline trajectory, gravity effects and fluid friction with pipeline walls.


Inputs & Outputs


InputsOutputs

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bodyp_0

Intake pressure 

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bodyp(l)

Pressure distribution along the pipe

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bodyq_0

Intake flowrate 

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bodyu(l)

Flow velocity distribution along the pipe

LaTeX Math Inline
body\theta (l)



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body--uriencoded--%7B\bf r%7D(l)



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bodyT(l)

Along-pipe temperature profile 



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body\rho(T, p)



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body\nu(T, p)



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bodyA

Pipe cross-section area  

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body\epsilon

Inner pipe wall roughness



Assumptions



Equations




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\bigg( 1 -  \frac{c(p) \, \rho_0^2 \, q_0^2}{A^2}   \bigg )  \frac{dp}{dl} = \rho(p) \, g \, \frac{dz}{dl}  - \frac{\rho_0^2 \, q_0^2 }{2 A^2 d} \frac{f({\rm Re}, \, \epsilon)}{\rho(p)}



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u(l) = \frac{\rho_0 \cdot q_0}{\rho(p) \cdot A}



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q(l) = \frac{\rho_0 \cdot q_0}{\rho(p)}


where

LaTeX Math Inline
body--uriencoded--f(%7B\rm Re%7D, \, \epsilon)

Darcy friction factor

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body--uriencoded--\displaystyle %7B\rm Re%7D = \frac%7Bu(l) \cdot d%7D%7B\nu(l)%7D

Reynolds number

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body--uriencoded--\displaystyle d = \sqrt%7B \frac%7B4 A%7D%7B\pi%7D%7D

characteristic linear dimension of the pipe

(or exactly a pipe diameter in case of a circular pipe)


See Derivation of Stationary Isothermal Homogenous Pipe Flow Pressure Profile @model.


Approximations



Incompressible pipe flow 
LaTeX Math Inline
body\rho(p) = \rho_0
with constant friction 
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body--uriencoded--f(%7B\rm Re%7D, \, \epsilon) = f_0


Pressure profilePressure gradient profileFluid velocityFluid rate


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p(l) = p_0 + \rho \, g \, z(l) - \frac{\rho_0 \, q_0^2 }{2 A^2 d} \, f_0 \, l



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\frac{dp}{dl} = \rho \, g \cos \theta(l) - \frac{\rho_0 \, q_0^2 }{2 A^2 d} \, f_0 



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u(l) = u_0 = \frac{q_0}{A} = \rm const



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q(l) =q_0 = \rm const


where

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body\displaystyle \cos \theta(l) = \frac{dz(l)}{dl}

correction factor for trajectory inclination


Expand
titleDerivation


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Incompressible fluid 

LaTeX Math Inline
body\rho(p) = \rho_0 = \rm const
 means that fluid velocity is going to be constant along the  trajectory 
LaTeX Math Inline
body--uriencoded--u(l) = u_0 = \frac%7Bq_0%7D%7BA%7D = \rm const
.

The Reynolds number 

LaTeX Math Inline
body--uriencoded--\displaystyle %7B\rm Re%7D = \frac%7Bu_0 \cdot d%7D%7B\nu_0%7D
 may still be varying along the trajectory due to the influence of temperature profile on kinematic viscosity 
LaTeX Math Inline
body--uriencoded--\nu(l) = \frac%7B\mu(T(l))%7D%7B\rho_0%7D




The first term in 

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anchorIFPGP
defines the hydrostatic column of static fluid while the last term defines the friction losses under fluid movement:


In most practical applications in water producing or water injecting wells the water can be considered as incompressible and friction factor  an be assumed constant

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body f(l) = f_s = \rm const
 along-hole ( see  Darcy friction factor in water producing/injecting wells ).



References


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