How to Specify Far Field Conditions for Drainage (RiverString) #84
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Thanks for the additional context. Here is what is going on: What may be confusing to you is that the transient RiverString element doesn't approach the steady RiverString element for large time. That is a well known characteristic of a transient model in a confined aquifer. The simplest case is a transient well (a Theis well). If you start pumping, the head far away will always be zero. A steady well (a Thiem well), always computes a head far away that keeps increasing. In fact, for a steady well in a confined system, the modeler has to define the distance at which the head equals zero. So the transient well never approaches the steady well in a confined system. You see exactly the same thing in your model. Only in a semi-confined aquifer you will see that the transient well approaches the steady well at large time. So in summary: the |
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Context:
We’re using timflow.transient (not steady) for dewatering simulations. Our workflow:
Goal:
Issue:
When we use RiverString alone with a large evaluation buffer (±600 m), we observe:
Attempts to Resolve:
Questions:
Minimal Example:
We started by using a RiverString element in TimFlow, with the phreatic line at 1.18 m and the target head at 0.27 m.
Without specifying boundary conditions or using a large buffer, the results near the RiverString were reasonable:
However, when we increased the buffer size (±600 m) to capture smaller drawdown values (e.g., 0.05 m) farther from the drain:
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