Introduce a perturbation during a simulation

ziggo · November 25, 2013, 20:07

In this article on unsteady CFD analysis of von Karman vortex shedding the following is said on page 3, section 2.3:

Quote:

When the steady state solution is achieved within about 80 time steps, a jet normal to the mean flow direction is introduced in the vicinity of the trailing edge during 10 time steps.

This is done to accelerate the occurrence of the vortex shedding.
How do I introduce a local jet normal to the flow in Fluent for a certain amount of time steps?

macfly · November 26, 2013, 12:14

Implement a DEFINE_PROFILE udf where the inlet velocity profile is dependent on the flow time with some conditional statements.

For an example of DEFINE_PROFILE and flow time, look for "UDF for specifying a transient pressure profile boundary condition" in the Ansys Fluent UDF Manual. Then look for "if-esle statement" in the same manual.

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November 26, 2013, 12:14		#2
macfly Senior Member François Grégoire Join Date: Jan 2010 Location: Canada Posts: 392 Rep Power: 17	Implement a DEFINE_PROFILE udf where the inlet velocity profile is dependent on the flow time with some conditional statements. For an example of DEFINE_PROFILE and flow time, look for "UDF for specifying a transient pressure profile boundary condition" in the Ansys Fluent UDF Manual. Then look for "if-esle statement" in the same manual.