Shape parameter for particles

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Shape parameter for particles

Post by arl.noaa »


I have a question about Hysplit that I haven't been able to answer myself by going through the manual or looking online. In the Concentration / Setup Run / Deposition definition, what are the values for the "Shape" parameter and what do they mean? I notice that Shape is set to 0.0 if the pollutant is a gas and 1.0 if the pollutant is a particle. I didn't know if there were other values or if all particles should be 1.0 and all gasses 0.0.
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Re: Shape parameter for particles

Post by glenn.rolph »

See ARL-224 in the documents directory. The shape factor is only applied to particles.

The settling velocity is then adjusted for a slip correction (Cc) for small particles and a dynamic shape factor (α) to account for non-spherical particles. Hence the final settling velocity is

Vs = Vg Cc α-1, (90)

where α can vary between 1.0 to 2.0
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