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Single inlet velocity experiment vs multiple velocity experiments

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Old   March 12, 2015, 13:05
Default Single inlet velocity experiment vs multiple velocity experiments
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Siddharth Kulkarni
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Hello all

I've simulated 5 tidal turbine blade geometries using transient SST turbulence model, in CFX at 2.5m/s inlet velocity and obtained satisfactory power, lift, and torque coefficient values. It took me weeks to get the converged results.

But my supervisor is asking me to simulate same set of geometries for more than one inlet velocity i.e. for 1.5, 2.0, 3.0, 3.5m/s.

Do I really have to simulate all the blade geometries for more than one velocity? or is there a justification to get away by just simulating for one inlet velocity? provided the computational overhead required.

Please help me this, I need to answer very urgently.

Kind regards

Siddharth
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Old   March 12, 2015, 16:45
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Glenn Horrocks
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Quote:
I need to answer very urgently.
I'm sure you do. Then talk to ANSYS support - you pay them to get urgent help. Nobody is paid here so we will answer when we get around to it.

The answer to your question is simple - if everything scales with flow rate then you can take a single simulation and scale it. But usually only very simple flows scale with flow rate. Things like boundary layer growth, separations, wake interactions and other complex factors usually mean that there is a significant departure from a simple scaling.

But it all depends on how accurate you want to be. If you are happy with a 25% error then scale the result. If you need to be more accurate then that then you will need to simulate them all.
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