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Wrong output concentration

Posted: Wed Dec 26, 2018 2:41 pm
by yarivts
Hello,
I'm trying to model a recovery treatment for a contaminated layered soil (20 m profile). My goal is to examine whether the existing pollutant will flushed down to the groundwater during the treatment. For simplification, the adsorption, diffusion and Henry coefficients were set to zero. The dispersion was set to 200 cm. Atmospheric b.c was set, applying 12 cm of rain during the first 4 days with zero evaporation and zero c top/bottom. Finally, I have specified the pollutant concentration along the soil profile (1.7e-5 g/cm3 at the depths of 0.5-2 m). However, the initial concentration at the results are very different from what i"ve specified (orders of magnitude larger). In addition, the relative error was close to zero.
Any solution or explanation for that problem will be helpful.
Many thanks,
Yariv

Re: Wrong output concentration

Posted: Wed Dec 26, 2018 3:50 pm
by Jirka
Not enough information. J.

Re: Wrong output concentration

Posted: Thu Dec 27, 2018 6:31 am
by yarivts
Hey, I have solved the problem. The problem was with specifying the initial condition in in total concentrations.
Thanks

Re: Wrong output concentration

Posted: Thu Dec 27, 2018 6:44 am
by yarivts
By the way, is there any good example on the website for transport of hydrocarbons/solute with high adsorption values?
Yariv

Re: Wrong output concentration

Posted: Tue May 14, 2019 6:26 am
by faith1796
Hello, friend. I have met the same problem, the mass unit I set was gram, while the length unit was meter. The initial concentration for COD was set as 52 [-]. But the result time series started from 2000 g/m3. Could you share the solution with this problem please? Thanks in advance.

Re: Wrong output concentration

Posted: Tue May 14, 2019 2:20 pm
by Jirka
It is impossible that HYDRUS-1D would start calculations with different initial concentrations in the liquid phase that those specified, unless you used the option to specify the initial conditions in terms of Total Concentrations, rather than in Liquid Phase Concentrations. In such case, HYDRUS-1D will distribute specified values (total concentration) among different phases (liquid, solid, and gaseous) based on specified coefficients (Kd, Kh, Beta, eta). J.

Re: Wrong output concentration

Posted: Fri May 17, 2019 3:17 am
by faith1796
Jirka wrote:
Tue May 14, 2019 2:20 pm
It is impossible that HYDRUS-1D would start calculations with different initial concentrations in the liquid phase that those specified, unless you used the option to specify the initial conditions in terms of Total Concentrations, rather than in Liquid Phase Concentrations. In such case, HYDRUS-1D will distribute specified values (total concentration) among different phases (liquid, solid, and gaseous) based on specified coefficients (Kd, Kh, Beta, eta). J.
I am using hydrus 2D to simulate. Yes, I specify the initial conditions in terms of total concentration. however, it still can't explain why the starting concentration is so much higher than the initial condition. Any clue or hint on that? Thanks

Re: Wrong output concentration

Posted: Fri May 17, 2019 2:05 pm
by Jirka
I have no more to add to this topic. J.