Flowrate

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Grant
Posts: 42
Joined: Fri Jul 31, 2020 3:42 pm
Location: Malaysia

Flowrate

Post by Grant » Sun Jun 23, 2024 5:29 pm

Hello,

Could you please clarify if the Ks is the only parameter we can adjust to control the flow rate? I simulated the transport of 4 solutes, and I observed that the effluent values appear at the observation nodes in less than an hour, possibly as soon as 30 minutes. I believe my Ks value is low enough to prevent immediate effluent. I expected effluent to appear after 1 hour. What could be causing this discrepancy?

Attached is the simulation for your reference.
4 solutes, with results.zip
(75.48 KiB) Downloaded 8 times

Grant
Posts: 42
Joined: Fri Jul 31, 2020 3:42 pm
Location: Malaysia

Re: Flowrate

Post by Grant » Sun Jun 23, 2024 10:06 pm

Hello,

Hopefully, you could help me on this.

Jirka
Posts: 6076
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Flowrate

Post by Jirka » Mon Jun 24, 2024 11:33 am

I'm teaching this week a HYDRUS short course in Prague. I will answer questions in the discussion forum later in the week when I'm less busy with the course. J.

Jirka
Posts: 6076
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Flowrate

Post by Jirka » Fri Jun 28, 2024 9:54 am

While Ks is the major parameter controlling the flow rate (at full saturation), it is not the only parameter controlling the movement of chemicals. For example, the average pore water velocity (which controls the movement of concentration fronts) is also affected by porosity (i.e., v=Ks/porosity). Additionally, solutes are retarded due to sorption (i.e., R=1+ro*Kd/porosity).

In your case, you have additionally large amounts of solute added to the system by zero-order production and removed from the system by first-order degradation. Thus, it is quite difficult to judge for an outsider (like me) to assess what you are doing.

J.

Grant
Posts: 42
Joined: Fri Jul 31, 2020 3:42 pm
Location: Malaysia

Re: Flowrate

Post by Grant » Fri Jun 28, 2024 2:42 pm

Thank you for the reply,

I am not sure if the kd and zero-order and first-order rate constants will be different if you increase the length of column in inverse solution. Do you know a journal/study that will confirm this?

Thank you and best regards.

Jirka
Posts: 6076
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Flowrate

Post by Jirka » Fri Jun 28, 2024 6:31 pm

I think you should really review some basic soil physics. I have nothing more to add. J.

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