The question about how to use nonequilibrium transport model (two-site model) in HP1

The HP1 code incorporates modules simulating
(1) transient water flow in variably-saturated media,
(2) transport of multiple components, and
(3) mixed equilibrium/kinetic geochemical reactions.
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Bowen Luo
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Joined: Fri Apr 28, 2023 6:02 am
Location: China

The question about how to use nonequilibrium transport model (two-site model) in HP1

Post by Bowen Luo » Fri Apr 28, 2023 6:54 am

Dear all,
I am working on a heavy metal migration problem that considers reaction processes. I am working on a heavy metal migration problem that considers reaction processes. I used the inverse solution module of the HYDRUS base module before adding a specific chemical reaction equation using the HP1 add-on module. And the results show that the fitting results of the nonequilibrium transport model (two-site model) is the best. Now I need to substitute the well-fitted parameters of the two-site model into the HP1 module for the next step.
I notice that only the equilibrium adsorption model can be used in module HP1, and the interface for Reaction Parameter input will not be displayed. I tried to modify the model parameters directly in the selector.in file by changing iNonEqul from 0 to 2 and then modifying the parameters Frac, Kd, Beta. It turns out that when I changed the Frac parameter, the program stopped running. When I modify only Kd and Beta parameters, the program runs. It turns out that when I changed the Frac parameter, the program stopped running. When I modify only Kd and Beta parameters, the program runs.
I have referred to the instructions and examples of HP1 provided by you, but I have not found a way to solve this problem, that is, how to use nonequilibrium transport model (two-site model) in HP1. I have seen an example of using the nonequilibrium transport model in HP1 in an article. I'm very much looking forward to getting a solution to this problem from here. Here is my HP1 file.
HP1_non-eq.zip
(575.42 KiB) Downloaded 410 times
Best regards,
Bowen

Jirka
Posts: 6059
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: The question about how to use nonequilibrium transport model (two-site model) in HP1

Post by Jirka » Fri Apr 28, 2023 12:53 pm

In HP1, the standard HYDRUS solver handles only physical processes, i.e., water flow and solute transport. Reactions (including instantaneous and kinetic sorption, which are involved in the two-site sorption model) are handled by PHREEQC, and thus have to be defined in its inputs (and not using the HYDRUS reaction parameters). J.

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