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-   -   shock wave in water (http://www.cfd-online.com/Forums/fluent/101261-shock-wave-water.html)

ndabir April 29, 2012 19:28

shock wave in water
 
Hi all,


Does anybody have any experience with simulating water as an compressible liquid in fluent? I have already written an udf file for relation between density and pressure. But since I want to use the explicit solver (because Fluent help says that this solver is better for capturing shock), when I use it I get this error:

"global time stepping cannot be used for incompressible flow"

however I have changed the material to water and the density and speed of sound to udf. I think this should be enough for fluent to realize that I am solving compressible flow.

Anybody has any idea how to get rid of this error?

LuckyTran May 1, 2012 14:48

Quote:

Originally Posted by ndabir (Post 358385)
Hi all,


Does anybody have any experience with simulating water as an compressible liquid in fluent? I have already written an udf file for relation between density and pressure. But since I want to use the explicit solver (because Fluent help says that this solver is better for capturing shock), when I use it I get this error:

"global time stepping cannot be used for incompressible flow"

however I have changed the material to water and the density and speed of sound to udf. I think this should be enough for fluent to realize that I am solving compressible flow.

Anybody has any idea how to get rid of this error?

You can't use global time stepping for incompressible flows (pressure-based solver) or density-based implicit time stepping.

Make sure you are using the explicit density based solver (regardless of how you use UDFs to take care of everything else).

ndabir May 3, 2012 13:50

Thanks for your reply. I use explicit solver (density-based) with a udf for water density. But still have the same error. it seems fluent cannot realize the udf. I guess the only EOS fluent supports with explicit solver is "Ideal gas".

has anybody simulated water as compressible with explicit solver?


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