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Diffusion of Chloride Problem
Posted 03.05.2015, 18:25 GMT-4 Chemical Reaction Engineering Version 5.0 0 Replies
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I am solving the diffusion problem of chloride ions. I used the Transport of Diluted Species module in 1D for an element 50 mm length, time dependent study, and calculated the concentration at x=50 mm with time. I compare the the results obtained with the closed form solution ( error function) and Life-365 Program (solve using finite difference).
When the inputs where: Diffusion = 6.5 e-12 m^2/s, Boundary C at( x=0) = 0.5 mol/m^3 , No flux, Initial value = 0
the results were almost the same.
But, when i started using variable boundary for concentration with time with all items constant, i defined a piece-wise function with name {cs1 (pw3)} as follows
argument: t
Extrapolation: constant
Smoothing: No smoothing
Intervals
start end function
0 365 0.5/365*t
365 3000 0.5 units for argument: days [d] for function: mol/m^3
in the boundary i defined the value of c = pw3(t)
and here i compared the results obtained with those of Life-365(using the same variables and constants) only as the erf is not solved for variable c .
the results is considerably different ( see attached photos). Is there any thing wrong i might have done or the two programs can not be compared.
Note: i also obtained difference results when the defined a function for diffusion with time
thanks a lot.
Hello Mohamed Sakr
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