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Outputs

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LaTeX Math Inline
bodyT(t, z)

Temperature distribution alon transversal direction to 

Inputs

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Inputs

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LaTeX Math Inline
bodyt

Time lapse after the temperature step from 

LaTeX Math Inline
bodyT(z=0) =0
  up to 
LaTeX Math Inline
bodyT(z=0) =T_f

LaTeX Math Inline
bodyz

Spatial coordinate along the transversal direction to constant temperature 

LaTeX Math Inline
bodyT(z)= T_f
plane 
LaTeX Math Inline
bodyz=0

LaTeX Math Inline
bodyT_f

Boundary temperature at 

LaTeX Math Inline
bodyz=0

LaTeX Math Inline
bodya

Thermal diffusivity of the surroundings


Equations

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Driving equationInitial conditions Boundary conditions


LaTeX Math Block
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\frac{\partial T}{\partial t} = a^2 \Delta T = a^2\frac{\partial^2 T}{\partial z^2}



LaTeX Math Block
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T(t=0, z) = T_G(z)



LaTeX Math Block
anchor7685E
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T(t, z=0) = T_f = {\rm const}, \quad T(t, z \rightarrow \infty) = T_G(z)



Solution

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LaTeX Math Block
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T(t,z) = T_f + (T_G(z) - T_f) \cdot \frac{2}{\sqrt{\pi}} \int_0^{z/\sqrt{4at}} e^{-\xi^2} d\xi



Approximations

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LaTeX Math Inline
body--uriencoded--\displaystyle \zeta = \frac%7Bz%7D%7B4 a t%7D \sim 0


LaTeX Math Block
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T(t,z) = T_f + (T_G(z) - T_f) \cdot \Bigg[  1- \frac{\exp(-\zeta^2)}{\sqrt{\pi} \zeta} \bigg( 1- \frac{1}{2 \zeta}  + \frac{3}{4 \zeta^3} \bigg) \Bigg]



See also


Heat flow equation for Semispace Linear Conduction:

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Replacing the static value of 

LaTeX Math Inline
bodyT_G(z)
 in RHK model with dynamic value of  
LaTeX Math Inline
bodyT_b(t, z)
 one arrives to the final wellbore temperature model with account of heat exchange with surrounding rocks and cooling effects from flowing units (Semispace Linear Conduction).


See also

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Physics / Fluid Dynamics / Linear Fluid Flow 

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