Negative concenteration

A discussion forum for users of the new HYDRUS 2D/3D. HYDRUS is a software package for simulating water, heat and solute movement in two- and three-dimensional variably saturated media. Happy Posting!
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mahdiye.latifi76
Posts: 10
Joined: Thu Sep 24, 2020 2:38 pm
Location: Iran

Negative concenteration

Post by mahdiye.latifi76 » Sun Nov 22, 2020 5:31 am

Hi, I callibrated HYDRUS for a drain and then run it for long-time, then concentration in some long-time cases became negative in some places, what is mean? can somebody please help me with this.
Thank you

Jirka
Posts: 5268
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Negative concenteration

Post by Jirka » Sun Nov 22, 2020 9:45 pm

The negative concentrations are likely the results of the oscillatory behavior of the numerical solution. See Chapter “6.4.6. Oscillatory Behavior” of the Technical Manual on how to avoid numerical oscillations (e.g., use options such as upstream weighting, artificial dispersion, or the performance index). J.

mahdiye.latifi76
Posts: 10
Joined: Thu Sep 24, 2020 2:38 pm
Location: Iran

Re: Negative concenteration

Post by mahdiye.latifi76 » Mon Dec 28, 2020 7:17 am

I studied the manual section that you adviced and did all the things that were mentioned there but I still have negative amounts of concentration. could you please guide me with this problem?
thank you

Jirka
Posts: 5268
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Negative concenteration

Post by Jirka » Mon Dec 28, 2020 5:46 pm

I do not have other advice beyond what I provided in my previous email. J.

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