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The most likely explaination is that the solution doesn't change much over the range of times you run the model. This could be because the physcics are either much slower or much faster than the time span of your run.

Best,

Jeff

Thank you.I want to study the dynamic problem of the electric double layer and the induced charge around the metal cylinder. Now the model has been established, which is a transient model. But the final calculation results do not change after I apply different times, and I only get a look of the electric double layer in a stable state. I can't see the change process of the electric double layer establishment.

The symptom you are describing is very consistent with the physics being fast relative to the solution time, so that all the transients are happening before the end of the first stored time. Another possible explanation could be that your initial conditions match the stationary state closely.

Best,

Jeff

Thank you.How to solve? Is it necessary to change the time step of the solver or the initial value boundary conditions and initial conditions ?

If the issue is the first one I mentioned, then make sure you run your model for a length of time that makes sense for the physics, and that you ask the software to store solutions at times that capture the transients. This requires that you estimate how long those transients are (from experience, or litterature, or non-dimensionlalization of the equations, etc).

If the issue is the second one I mentioned, then you need to make sure your problem is set up so that it is not already at steady-state in its initial conditions.

Best,

Jeff

Thank you very much. I'll revise it from these two points.