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Old   April 29, 2012, 20:28
Default shock wave in water
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navid
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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?
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Old   May 1, 2012, 15:48
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Lucky Tran
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Quote:
Originally Posted by ndabir View Post
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).
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Old   May 3, 2012, 14:50
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navid
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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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