September 12, 2023 at 1:56 pmAlbi.PaniSubscriber
Hi, I am simulating a simple fdtd simulation with a plane wave with no incidence angle and amplitude of 10^8 in free space.
Then I visualize the results on a "frequency-domain field and power monitor" that is parallel to the axis of propagation.
What should I expect to see?
I expect a plane wave when I look only at the wavelength of 367 nm but I have different results on the monitor:
Why does a plane wave appear with wavelength of 317 nm, that has also an higher amplitude than the injected one?
September 12, 2023 at 5:01 pmGuilin SunAnsys Employee
What you expect is the amplitude but what you visualize is the real part.
so you can visualize the amplitude, eg, choose Abs instead of Re.
September 12, 2023 at 6:09 pmAlbi.PaniSubscriber
thank you for your answer but the problem is the same. I see an high amplitude also in the wavelength where no plane wave should exist, as you can see in the third picture. Why?
September 12, 2023 at 7:12 pmGuilin SunAnsys Employee
I am not sure what do you mean "the problem is the same". I do not believe the Abs (absolute value) and the Re (real part) give the same result.
As for " high amplitude also in the wavelength where no plane wave should exist", it is normal. Please check the source spectrum: when there is a pulse, it has much broader spectrum than what you specified in bandwidth. The latter is to ensure the intensity within the specified bandwidth is large enough to lead to accurate normalized result: Understanding frequency domain CW normalization
Your result once again shows that we should only record and get the result within the source bandwidth, not outside of it. When the source intensity is small, dividing a small number can lead to large error.
September 13, 2023 at 1:02 amAlbi.PaniSubscriber
Thank you. Unfortunately in my final simulation I am trying to simulate a non linear process so I can not use a pulse. But I will think about it.
September 13, 2023 at 3:33 pmGuilin SunAnsys Employee
If you do not use pulse, then you may need to carefully rethink the frequency-domain result from Fourier transform as it requires the signal decays completely. Probably you can use the real part from the time monitor which only records the fields at the end of the simulation. Please take sometime.
- You must be logged in to reply to this topic.
Boost Ansys Fluent Simulations with AWS
Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.
- “Import optical generation” or “delta generation rate”?
- Why am I getting “process exited without calling finalize”, and how do I fix it?
- Using a license file on a new license server
- Ansys Insight: Diverging Simulations
- Error: addfdtd is not a valid function or a variable name
- Questions about the calculation of the cross-polarization conversion efficiency of metasurface
- Error on Lumerical device
- Ansys Insight: About override mesh in FDTD: its use and settings
- Finding your Ansys (or Lumerical) account number
- Lumerical – error message when trying to open from Linux terminal
© 2023 Copyright ANSYS, Inc. All rights reserved.