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spatialtime March 10, 2010 08:19

Harmonic Methods (frequency domain techniques)
Dear CFD experts,

Is it possible to run a frequency domain technique analysis (e.g. harmonic balance method) in FLUENT or CFX?

What other CFD software, capable of doing FSI simulations, can do such analysis?

I know that it's possible to do it with Star CCM+ 4.04 (harmonic balance method) and NUMECA FINE/TURBO (Non Linear harmonic NLH method). The disadvantage of the FINE version is that it can only do it in the turbomachinery problems module. Is there a way around to do it generally for self-defined problems? The same disadvantage exists for Star CCM+.

I hope to hear from you!

Kind regards,

b33 June 25, 2010 21:58

Harmonic Methods

I'm not sure which other CFD softwares have this capability, but I do know that the technology is suited particularly to turbomachinery for one reason: the physical processes (and therefore solution sets) are periodic in nature, and both solution methods make the assumption that the fluctuations due to the periodic passing of a blade (from both upstream and downstream contributions) are preponderant over the random turbulent fluctuations that happen in the flow-field.

So basically, if you were to apply their methods to an unsteady flow field problem that wasn't periodic in nature, it wouldn't work very well at all. (Numerical solution methods with Fourier series representations of discontinuities in a function = disaster...Gibbs phenomena at shock waves, etc)

spatialtime June 28, 2010 04:52

Thanks for your reply b33. However the intention was to apply it on oscillating problems. By example flutter of a wing. Or an oscillating cilinder (moving sinusoidal with a certain fixed frequency) in a channel, etc.

DoHander June 28, 2010 11:26

Not really sure but I think you can use NASTRAN for frequency analyze ...

Fluent works only in time.


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