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unit for lilley source

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Old   March 6, 2006, 05:14
Default unit for lilley source
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azmir
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I just tried the aeroacoustic model and very new at this. What is the unit or dimension for the lilley aeroacoustic source results? When plotted, no dimension/unit was displayed.
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Old   March 14, 2006, 04:59
Default Re: unit for lilley source
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azmir
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From the equations, it seems to be [s^-3], which means what physically? How is this aeroacoustic source utilized in analysis? Or does it have to be coupled with another set of scalar results in order to enable physical sense/interpretation/correlation?

Please, I am just starting on this aeroacoustic and would appreciate something to get me off the ground.
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Old   March 18, 2006, 10:50
Default Re: unit for lilley source
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Jim
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The Lilley source term is effectively dimensionless. It is used as a qualitative measure of the noise source intensity at various points in the flow - i.e. a high value means there's lots of noise being generated, and a low value means there isn't lots of noise being generated. This means you can use it to compare two designs.

In order to obtain absolute values (e.g. dBs) you generally have to run a transient analysis, then perform a fourier transform on your transient pressure data.
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Old   March 19, 2006, 20:25
Default Re: unit for lilley source
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azmir
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finally someone responded! thank u very much!

I got 1/s^3 to be the unit from the equations described in methodology. From there, it seems as if it should be multiplied by another term (from another set of analysis perhaps) to get more physically meaningful results.

If u say it's dimensionless (what do u mean by 'effectively' though?), I hope u are right.

I have sorta interpreted the plot as u suggested already but since this is a new type of result (probably different from Fluent's CAA as well), my audience have been asking lots of questions which I couldn't well answer. The method of obtaining dB is not novel. And thank you once again.
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