DrNinjaman
Mechanical
I'm performing a 3D uncoupled acoustic analysis of a large machinery house with numerous sound sources.
I have octave band sound power data for the various sources as well as the octave band absorption coefficients for the enclosure walls.
I'm interested in the total sound pressure level in various locations throughout the house for determining exposure time for personnel. Since Ansys solves for a given frequency, I'm currently performing a load step solve at each of the octave band frequencies, with the intention of combining the frequency band results to get the overall sound pressure level in the house.
I have 2 questions though:
1. Is there any mesh size requirement for good results relative to the sound wavelength?
I'm using roughly a 12inch mesh global size for the volume mesh, and my results plots look strange for the frequencies above 1000Hz. I'm thinking it might be from a sort of sampling rate error, where the element size has to be less than half the wavelength, but I'm just speculating.
2. Is there any way, in Ansys, to combine multiple load steps (like sound pressure level@freq n) into a single value per element via the formula 10 log(10^(DB@freq 1 /10)+10^(DB@freq 2 /10)+...+10^(DB@freq n /10))?
I'd really like to be able to create a total sound pressure level contour plot, so doing this calculation in Ansys would be preferred.
Samuel F. Haworth
Bucyrus International, Inc.®
This...is my voice...on T..V...
I have octave band sound power data for the various sources as well as the octave band absorption coefficients for the enclosure walls.
I'm interested in the total sound pressure level in various locations throughout the house for determining exposure time for personnel. Since Ansys solves for a given frequency, I'm currently performing a load step solve at each of the octave band frequencies, with the intention of combining the frequency band results to get the overall sound pressure level in the house.
I have 2 questions though:
1. Is there any mesh size requirement for good results relative to the sound wavelength?
I'm using roughly a 12inch mesh global size for the volume mesh, and my results plots look strange for the frequencies above 1000Hz. I'm thinking it might be from a sort of sampling rate error, where the element size has to be less than half the wavelength, but I'm just speculating.
2. Is there any way, in Ansys, to combine multiple load steps (like sound pressure level@freq n) into a single value per element via the formula 10 log(10^(DB@freq 1 /10)+10^(DB@freq 2 /10)+...+10^(DB@freq n /10))?
I'd really like to be able to create a total sound pressure level contour plot, so doing this calculation in Ansys would be preferred.
Samuel F. Haworth
Bucyrus International, Inc.®
This...is my voice...on T..V...
