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-   -   Running stably with a large Courant number using pimpleFoam (http://www.cfd-online.com/Forums/openfoam/69466-running-stably-large-courant-number-using-pimplefoam.html)

mlawson October 23, 2009 16:14

Running stably with a large Courant number using pimpleFoam
 
2 Attachment(s)
I am attempting to simulate laminar incompressible pulsatile flow in a complex geometry. To adequately resolve my geometry I need at least 15 million cells. I am driving the flow by setting the pressure and the outlet and oscillation pressure at the inlet.

Currently I am using pimpleFoam with automatic timestep adjustment to maintain a max Courant number of 2. Using a higher Courant number causes the solution to become unstable.

My problem is that at a max Courant number of 2 my timesteps are between 1E-5 and 1E-6 seconds. I need to simulate at least 1 second of time, which would require at least 100,000 timesteps at my current timestep. Given the size of my model, solving this many timesteps is computationally prohibitive.

I'm using fvSolution and fvSchemes dictionaries directly from the pimpleFoam tutorial in OF-1.6 (see attached).

Does anyone have any suggestions on how I could increase my timesteps by a couple orders of magnitude to make this simulation feasible? Should I be using a different solver? Should I be using a different discretization scheme?

Any help would be appreciated,
-Mike

Djub July 13, 2012 06:04

Hi Mike,

Did you solve your problem?
I am trying to run a case with a very large Reynolds number (2.5e8). So I would like also to run with a large Co (Courrent flow) to limit my time calculation.
Does anyone has a solution? Or maybe an explanation that what I am looking for does not exist (and cannot exist)? Maybe the Co cannot be greater thant 1 in an unsteady flow?
In that case, is there in OpenFoam any Explicit algorithm for unsteady, incompressible, turbulent, newtonian flow ?


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