Seepage flow at inclined slope

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Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Seepage flow at inclined slope

Post by Hirof » Thu Apr 04, 2019 11:00 am

I'm using HYDRUS 2D and have some troubles.
I'd like to simulate the seepage flow in two dimension which is tilted at 20 degrees angle.
I've set the seepage face at the downslope boundary and gave the rainfall input of 0.02mm/h at the surface boundary.
When I started the simulation, while water infiltrated perpendicular to the slope surface,
water did not flow in downward direction.
Could you please tell me how to correct these situation?

Jirka
Posts: 4714
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Seepage flow at inclined slope

Post by Jirka » Thu Apr 04, 2019 4:34 pm

Flow inside of the transport domain is governed by the Richards equation and will thus be in the direction of the total head (pressure head+gravity) gradients. You cannot control the direction of flow, as it is a result of this numerical solution. When the gravitational component dominates the total head gradient, flow will be in the vertical direction.

The flow into the domain across the boundary is simply defined (in this numerical scheme) as inflow through boundary nodes. The inflow for any boundary node is calculated as a specified boundary flux (rainfall), multiplied by the length of the boundary (usually a half length of the boundary element on each side of the node) associated with the node. One can consider the total length, or only its horizontal projection (this should be used for vertical fluxes, such as rainfall). The selection whether the total length or only its horizontal projection is used is made using the check box "Consider only horizontal projections of boundary elements for Time-Variable Flux BCs)" in the dialog window "Boundary Conditions Options".

J.

Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Re: Seepage flow at inclined slope

Post by Hirof » Sat Apr 06, 2019 7:16 am

Hello Jirka,

Thank you very much for your quick response.
I'm sorry that I don't understand how to correct the settings.
I attached the result of the simulation.
Initial conditions is the pressure head of -100cm and the constant flux of the slope surface is 0.03 [cm/min]
The head was not changed and remained -100cm until about 1000 minutes later. (Image 1)
Suddenly, the head increased from the upslope. (Image 2)
I think my settings of the simulation is completely wrong, but I'm not sure what and how is wrong.
Please tell me the accurate settings.

Regards,
Hirof

Jirka
Posts: 4714
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Seepage flow at inclined slope

Post by Jirka » Sat Apr 06, 2019 5:53 pm

I do not see any attachments. J.

Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Re: Seepage flow at inclined slope

Post by Hirof » Sat Apr 06, 2019 8:18 pm

Hello, Jirka,

Thank you for replying.
I’m sorry I couldn’t attach the files.
Please tell me how to do it.

Regards,
Hirof

Jirka
Posts: 4714
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Seepage flow at inclined slope

Post by Jirka » Sat Apr 06, 2019 10:06 pm

I'm happy to help, but this is something you should certainly be able to figure out by yourself (as did tens of other users of this discussion forum). J.

Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Re: Seepage flow at inclined slope

Post by Hirof » Sun Apr 07, 2019 8:04 am

Hello Jirka,

I didn't know that just drag-and-dropping is ok.
Here are two images.
Image1 is 1000 minutes after the onset of simulation and image2 is 1460 minutet after the onset.
The left side of the rectangle that is tilted at a 20 degrees angle is seepage face, the slope surface is inflow boundary of 0.03cm/min and the other boundary is no flux. Domain type is 2D-simple vertical plane XZ.
Despite of the inflow(rainfall) and the slope angle(20) the pressure head remained -100cm until 1000min later and the upslope was higher pressure head than the downslope after about 1100 minutes.
Could you please tell me what setting was wrong.

Regards,
Hirof
Attachments
Image1.jpg
Image1.jpg (138.37 KiB) Viewed 341 times

Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Re: Seepage flow at inclined slope

Post by Hirof » Sun Apr 07, 2019 8:06 am

Image2 was attached.
Attachments
Image2.jpg
Image2.jpg (151.72 KiB) Viewed 340 times

Jirka
Posts: 4714
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Seepage flow at inclined slope

Post by Jirka » Sun Apr 07, 2019 2:47 pm

Clearly there is something wrong with your setup, giving that you have pressure heads of 5000 cm on the right side of the domain. J.

Hirof
Posts: 6
Joined: Thu Mar 21, 2019 4:24 am
Location: Japan

Re: Seepage flow at inclined slope

Post by Hirof » Mon Apr 08, 2019 2:44 am

Thank you , Jirka.
I try to find out what is wrong .
Hirof

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