[mcc007]

Hello everyone,

I have some questions about my simulation. I use Fluent 6.3.26 to simulate plasma interaction with liquid (water). When I tried time step size 1 s with different number of time steps (e.g., 100, 300, 600, etc.), I could get stable results. But the result (electric potential) seems too high than I expected. Because the average electric potential shown in the figure is around -5.e+10 V. But I only applied -2.5e+3 V. See the attachment in the first figure.

So I reduced my time step size to 1e-4 s and used a small number of time steps (less than 100), the result seems to make sense. However, ff I increased the number of time steps to 150 or even larger, then I have errors for my simulation: under convergence history of a UDS: 1.#QNBe+00.

My questions are:

1. why at high time step, the result is higher than expected?

2. why I choose a smaller time step size, the result is reasonable but the increase of number of time step leads to simulation errors: under convergence history of a UDS: 1.#QNBe+00.

I am wondering if you could help me with this.

Thanks a lot,
mcc007