specify No flow boundary

[praveen kumar]

Hi everyone.

As i am trying to define no flow boundary through the constant head boundary condition at the two sides of the model domain and another two constant head (100& 91m) . I am defining the "Zero" in the starting and ending head column, but during the translation an error is occurred . Please suggest me how to define  no flow boundary in visual modflow flex.

thanks in advance

Regards,

Praveen

[Richard B. Winston]

No flow boundaries are specified by making cells inactive. Also, the edge of the grid is automatically a no flow boundary.

[Boyce, Scott E]

If I had to guess at your problem is that you have your model layer defined as CONVERTIBLE (variable transmissivity/unconfine flow) rather than CONFINE. If you have a convertible layer with a head below the bottom of the cell it becomes "DRY" and is not included in the simulation. This creates a conundrum if you have a constant head set to value below the bottom of the cell because a convertible layer marks it as DRY but the constant head says there is water there. CONFINE layers allow for the head to go below the bottom of the cell.

The same goes for your initial head, if you give it a water level that is below the bottom of an active cell then it technically immediately becomes dry.

Some fixes is to either make the layer CONFINE, enable WETing, set the IBOUND=0 for those cells, or just make the starting head slightly above the bottom of the cell.

MODFLOW by default makes all IBOUND=0 cells no flow. So anywhere you have IBOUND=0 is analogous to solid rock/no flow.

Hope that helps out,

Scott

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From: mod...@googlegroups.com <mod...@googlegroups.com> on behalf of praveen kumar <praveenk...@gmail.com>
Sent: Monday, November 28, 2022 7:06 PM
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Subject: [EXTERNAL] [MODFLOW] specify No flow boundary

 

 

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[Faraji Kassim]

Wow..based on your email,i solved  my model problems.

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Regard

Eng. Faraji Kassim Abdallah - PEng (T)

Hydrologist / Hydraulic Engineer.

Po Box, 191.

Dar Es Salaam,

Email : farajik...@gmail.com.

Mobile: +255-743 986 799

              +255-685 117 528.

MINISTRY OF WATER

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