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Old   February 23, 2005, 05:56
Default changing boundaries
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sankar
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I want to simulate a model with let say five inlets and one outlet,but all inlets should not work at a same time that means inlets are time dependent. Suppose i want to trigger first 2 inlets rest inlets should be treated as wall and then as one time step is over next inlets should be triggered. STAR-Cd user guide says we can do that by advanced transients option and GT-power but how to use that and how to redefine the boundary type e.g changing from wall to inlet and vice versa i dont know. If anybody help me out of this i wld be grateful.
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Old   February 23, 2005, 09:53
Default Re: changing boundaries
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Pauli
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Can you leave it as an inlet and set the velocities to zero? In other words, when an inlet isn't flowing, you live without wall type functionality - say heat transfer or wall functions.

If so, you can define a time dependent velocity with a table or user subroutine (I believe it's bcdefi.f).

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Old   February 24, 2005, 05:06
Default Re: changing boundaries
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Brian
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The correct way to do this is using load steps - see "Analysis Controls for Transient Problems" - "Load-step based solution mode" in the User Guide.
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Old   February 25, 2005, 02:38
Default Re: changing boundaries
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sankar
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in user guide they are not specifying any info about changing boundary type with change of time. any other help is available anywhere?
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Old   February 26, 2005, 06:33
Default Re: changing boundaries
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Brian
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The boundary conditions, together with boundary types, are saved for each load step. So create a load step, set up the boundaries for that load step, then save the load step. Repeat for each load step - you can change boundary type as well as values.

Also note the use of ramp or step changes in load steps.
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