Two quick questions about HYDRUS (2D/3D)

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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Chaozi
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Joined: Wed Apr 12, 2017 11:19 pm
Location: USA

Two quick questions about HYDRUS (2D/3D)

Post by Chaozi » Mon May 22, 2017 11:43 pm

Dear Professor Šimunek,

I have two quick questions about HYDRUS (2D/3D):

1. I was wondering if it is possible to set different values for vertical saturated hydraulic conductivity and horizontal saturated hydraulic conductivity?

2. I set the initial time step as 0.5 min and minimum time step as 0.5 min when I did a solute transport simulation, but the model still simulated every 0.1 min and took a very long time. I was wondering if it is possible to force the time step longer?

Thank you very much in advance,
Chaozi

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

Re: Two quick questions about HYDRUS (2D/3D)

Post by Jirka » Tue May 23, 2017 2:07 am

1. Having different conductivities in different directions can be accomplished in Hydrus using the anisotropy tensor. In 2D, you can have different conductivities in the vertical and horizontal direction (or in any other direction), in 3D, you can have different conductivities in all three directions (using the anisotropy tensor).
2. In addition to conditions specified in Time Information (i.e., the initial time step, minimum and maximum allowed time steps), there are also conditions that are determine by numerical stability. When you simulate solute transport, the time step is also governed by the Courant condition and the product of the Courant and Peclet numbers (see the manual). Make sure that you specify the dispersivity value, since when you not do that, the Peclet Number is large, forcing the Courant number to be small, and correspondingly the allowed time step.

J.

Chaozi
Posts: 2
Joined: Wed Apr 12, 2017 11:19 pm
Location: USA

Re: Two quick questions about HYDRUS (2D/3D)

Post by Chaozi » Tue May 23, 2017 6:18 pm

Okay, I see.

Thank you very much, Professor Šimunek!

Chaozi

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