Hi Mohsen, Thanks for your email! Your methods did work! Thank you so much! I have one more question is that when I restart the simulation, I didn’t get the exactly same result. Say first I simulated 20 unit time from initial conditions (1, 0, 0). In order to compare with the results, then I simulated 10 unit time from initial conditions (1, 0, 0) and restarted at the 10th unit time to get another 10 unit time. And I found, for example, the 11th solution from my first simulation is really close to 11th simulation from second but not exactly the same. I think the reason is the approximation and unsteady of the algorithm. Is that correct? Best, Zhikang
On Feb 22, 2022, at 5:23 AM, Lahooti, Mohsen <m.lahooti@imperial.ac.uk> wrote:
Hi Zhikang Dong,
I believe you are using the Jupyter tutorials, right? In those tutorials, we set the "FinalTime" parameter for the simulation where together with the time step it will calculate the required number of steps. the problem you are facing is that after you use the previous simulation as initial conditions, you need to set a new "FinalTime" greater that in your initial conditions. Let's say you run the first simulation for 10 unit time, now in your second simulation you want to run the simulation for an additional 15 unit time, hence the final time becomes 10+15=25.
You can also simply delete the "FinalTime" parameter and based on your TimeStep and desired simulation time, calculate the number of steps manually and set it in the session file.
Hope this solve your problem
Cheers, Mohsen From: nektar-users-bounces@imperial.ac.uk <mailto:nektar-users-bounces@imperial.ac.uk> <nektar-users-bounces@imperial.ac.uk <mailto:nektar-users-bounces@imperial.ac.uk>> on behalf of 董智康 <darrendongzhikang@gmail.com <mailto:darrendongzhikang@gmail.com>> Sent: Sunday, February 20, 2022 5:35 AM To: nektar-users <nektar-users@imperial.ac.uk <mailto:nektar-users@imperial.ac.uk>> Subject: [Nektar-users] 2D Incns solver(tutorial) restart simulation raises error
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Hi all,
I am new to Nektar++, I was running tutorial: Incompressible Flow Simulation. When I tried to restart simulation by running code in 6.5 Optional additional tasks (Exercise1), it raised error
Initial Conditions: - Field u: from file cyl2DMesh.fld - Field v: from file cyl2DMesh.fld - Field p: from file cyl2DMesh.fld Fatal : Level 0 assertion violation m_timestep < 0
I followed all instructions before, I’m not sure where I was wrong. It’s really confusing. Could you please help me with that? Thank you so much and have a good day.
Best, Zhikang Dong