Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Input Multiple frequencies
Posted 28 déc. 2015, 00:01 UTC−5 Studies & Solvers 5 Replies
Please login with a confirmed email address before reporting spam
Hello,
In a pressure acoustics simulation that I am working on, I have the input pressure pulse of varying frequencies. I am doing a frequency domain study and the pressure wave is something like this.
P= Pa*sin(F1*t)+Pb*sin(F2*t).
As you can see, the pressure Pa and Pb are different pressure amplitudes and F1 and F2 are different frequencies.
Is it possible in frequency domain.?
Your help will be much appreciated.
Thanks!
In a pressure acoustics simulation that I am working on, I have the input pressure pulse of varying frequencies. I am doing a frequency domain study and the pressure wave is something like this.
P= Pa*sin(F1*t)+Pb*sin(F2*t).
As you can see, the pressure Pa and Pb are different pressure amplitudes and F1 and F2 are different frequencies.
Is it possible in frequency domain.?
Your help will be much appreciated.
Thanks!
5 Replies Last Post 30 déc. 2015, 06:44 UTC−5
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Dear Hari,
There are several ways to do that. One way involves solving the frequency domain problem at two frequencies F1 and F2, for a unit load (Pa=Pb=1). Then, in post-processing, multiply each solution by its load magnitude and add them up.
Nagi Elabbasi
Veryst Engineering
There are several ways to do that. One way involves solving the frequency domain problem at two frequencies F1 and F2, for a unit load (Pa=Pb=1). Then, in post-processing, multiply each solution by its load magnitude and add them up.
Nagi Elabbasi
Veryst Engineering
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Dear Nagi,
Thank you so much for your suggestion.
I have tried it on my model. But I have some questions.
-By adding in post processing do you mean join the two solution sets by adding them with sufficient weights? I went ahead with this method and it worked to a certain extent, which brings me to the second question.
-In the above, why is it that I cant get a far field polar plot when I use the data set as the join of solutions?
-Is there any other way to solve the original problem(You said there were a number of methods).
I would be extremely grateful if you have any suggestions. Meanwhile, I would work on my problem, and post here if I come up with useful solutions.
Thanks!
Thank you so much for your suggestion.
I have tried it on my model. But I have some questions.
-By adding in post processing do you mean join the two solution sets by adding them with sufficient weights? I went ahead with this method and it worked to a certain extent, which brings me to the second question.
-In the above, why is it that I cant get a far field polar plot when I use the data set as the join of solutions?
-Is there any other way to solve the original problem(You said there were a number of methods).
I would be extremely grateful if you have any suggestions. Meanwhile, I would work on my problem, and post here if I come up with useful solutions.
Thanks!
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Hi,
Just wanted to add something here.
I got another way to get the solution. So what i did was do a parametric sweep in the frequency domain study, with specific combinations of parameters. The parameters were the frequencies(F1 and F2) and the corresponding intensities. Once that was done, I did a simple join of the two solution sets by taking a sum and I got similar (almost identical) results!
Still cant plot a combined polar plot, but I could get the SPL polar plots for different frequencies, and plot them on the same graph.
Thanks!
Just wanted to add something here.
I got another way to get the solution. So what i did was do a parametric sweep in the frequency domain study, with specific combinations of parameters. The parameters were the frequencies(F1 and F2) and the corresponding intensities. Once that was done, I did a simple join of the two solution sets by taking a sum and I got similar (almost identical) results!
Still cant plot a combined polar plot, but I could get the SPL polar plots for different frequencies, and plot them on the same graph.
Thanks!
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Hari,
which meaning would a combined far field plot for two (or more) frequencies have? There is no well defined phase relationship for two different frequencies in the far field. From a practical standpoint: have you ever seen combined far field plots of any antenna for more than one frequency or a frequency band? I haven't.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
which meaning would a combined far field plot for two (or more) frequencies have? There is no well defined phase relationship for two different frequencies in the far field. From a practical standpoint: have you ever seen combined far field plots of any antenna for more than one frequency or a frequency band? I haven't.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Hi Edgar,
Thank you for your response.
I don't think I made my point clear enough. What I have as a point source is a bubble that oscillates in an acoustic field, scattering a pulse of a frequency. This bubble gives out scattered waves with a combination of frequencies. I performed a fourier analysis and isolated the dominant frequencies. Now I want to treat the bubble as a point source emitting acoustic radiation at those frequencies.
So what I am thinking is
-shouldn't the far field polar plots reflect the effects of all the dominant frequencies?
-in order to do that, I combined the solutions from the different parameters of the parametric sweep, and tried making the far field plot. I think I am wrong with this second logic.
Please correct me if I am wrong in any of the steps above. Any help from you would be much appreciated!
thanks!
Thank you for your response.
I don't think I made my point clear enough. What I have as a point source is a bubble that oscillates in an acoustic field, scattering a pulse of a frequency. This bubble gives out scattered waves with a combination of frequencies. I performed a fourier analysis and isolated the dominant frequencies. Now I want to treat the bubble as a point source emitting acoustic radiation at those frequencies.
So what I am thinking is
-shouldn't the far field polar plots reflect the effects of all the dominant frequencies?
-in order to do that, I combined the solutions from the different parameters of the parametric sweep, and tried making the far field plot. I think I am wrong with this second logic.
Please correct me if I am wrong in any of the steps above. Any help from you would be much appreciated!
thanks!