# Harmonic Methods (frequency domain techniques)

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 March 10, 2010, 08:19 Harmonic Methods (frequency domain techniques) #1 New Member   Join Date: Apr 2009 Posts: 12 Rep Power: 10 Sponsored Links 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, Mab Last edited by spatialtime; March 12, 2010 at 06:22.

 June 25, 2010, 21:58 Harmonic Methods #2 New Member   Ben Join Date: Mar 2010 Posts: 1 Rep Power: 0 Mab, 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)

 June 28, 2010, 04:52 #3 New Member   Join Date: Apr 2009 Posts: 12 Rep Power: 10 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.

 June 28, 2010, 11:26 #4 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 12 Not really sure but I think you can use NASTRAN for frequency analyze ... Fluent works only in time. Do

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