Entries for October 6, 2016

I used the timestep of 0.05s, it has passed 3035s physical time and keeps on running. The maximum courant no. and average courant no. are 0.29 and 0.035 respectively. So the smaller timestep (0.05s) really works.

I calculated the courant no.

The maximum velocity is approximately 18m/s at the top. and if the time step is 0.15s, the courant no. is 1.08 (dx = 2.5m). So the time step indeed should be decreased. But the time step in the last step is 0.015s, the courant no. is 0.108. It is pretty small. So I slightly increased the time step to 0.05s. I got 1000s physical time after 1 day, so I expect I can get 300-400s physical time after 1 day running.

I run a simulation case from NREL in OpenFOAM 2.1.1 (3km*3km*1km). I would like to use this case and solver (ABLSolver) to simulate the flow field in wind farm. I refined a region for wind turbine in this case (detx=2.5m).

The case works pretty well before 3035s. From 3035s, the max courant no. increased instantly from 0.75 to 2.6e+25. I used adaptive time step and the maximum time step is set to be 0.5 (it is normally 0.15 because of max courant no.) and maximum courant no. is 0.75....