Flux through 3rd BC

Hi,

I run a 3D steady state flow-transient transport model, and used the Budget Analyzer to calculate the flux through a 3rd BC, and obtained a value of -1646 m3/d. I then reduced the model to a flow only model (still steady state), and run the model again. I then calculated the flux through the same 3rd BC, and obtained a value of -4 m3/d. Any one had the same problem as I did? I think the flux should be the same, but FEFLOW gave a really different value. I appreciate your help.

Zheng

When using the "steady flow/transient transport"-option, you have to make sure that the flow field is already in equilibrium, i.e. by running it first as a steady state flow-only model. FEFLOW will perfom a single iteration on the flow calculation and then proceed with the transient transport model. If the flow-field is not in steady-state by this time, you will get obstruse results (see also FEFLOW help system).

Does your model as well incorporate mass-density relationships? This can also affect your flow-field if "steady flow" is chosen, since FEFLOW still calculates density driven flow in its calculation (The term of the so called Boussinesq-approximation is still active, see Reference-manual ch. 1.10 for more explanation).

Hi Alex,

Thanks a lot for your reply.

I did run it as a steady state flow-only model first, and everything looks fine. My work flow is:

1. Build this 3D steady state flow-transient transport model;

2. Reduce this model to a steady-state flow-only model, and run it. The results look fine.

3. Run the original steady state flow-transient transport model. And check the results.

And the results I mentioned in my first post happened. I do not want to incorporate mass-density relationships in my model. I do not know how to incorporate this relationship. I think my model does not incorporate mass-density relationships.

I appreciate your help in this regard.

Zheng