Menu

Discussion Forum

New Discussion
查找

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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.

Heaviside problem

Posted 2015年12月20日 GMT-5 09:14 Low-Frequency Electromagnetics, Fluid & Heat, Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4 3 Replies

Mindaugas Visockis
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello for everybody ,

I am trying to make a square pulse train, and was read a lot of forums for this..but unfortunately I didn't get pulse train...just one 5us pulse with DV amplitude..

My rectangular pulse train function is:

DV*(flc2hs(mod(t[1/s],0.1)-1e-9,1e-9)-flc2hs(mod(t[1/s],0.1)-tp,1e-9))

there is :
DV - pulse amplitude (30000 V),
0.1 s - pulse period
tp - pulse width (10us)

So where is a problem and why I don't get a correct pulse train.. ???

Thanks a lot,

Mindaugas
3 Replies Last Post 2015年12月29日 GMT-5 13:30
Edgar J. Kaiser Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年12月20日 GMT-5 09:41
The function seems to be correct. You are just not plotting far enough and you have to create a plot with a high resolution grid dataset (100000) otherwise you don't resolve the sharp spikes in the plot.

If you are planning to use this in a time dependent study, you have to take care that the time stepping resolves the spikes. The rectangular pulses will probably get the solver into troubles. You may have to make it smoother.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
The function seems to be correct. You are just not plotting far enough and you have to create a plot with a high resolution grid dataset (100000) otherwise you don't resolve the sharp spikes in the plot. If you are planning to use this in a time dependent study, you have to take care that the time stepping resolves the spikes. The rectangular pulses will probably get the solver into troubles. You may have to make it smoother. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Mindaugas Visockis
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年12月20日 GMT-5 10:57
Thanks a lot ! , You are right.

I am planing use this function to express pulsed electric field. I have acrylic tube in which inner wall is inserted two parallel electrodes (Ground and Potential). Dielectric in tube inside is a fluid. This fluid must flow through the tube.

First of all, I want to see distribution differences between pulsed electric field and stationary electric field.

Secondly, very interesting for me is distribution differences of heat dissipation.

So I want to develop model which could be used to analyse the impact of different process parameters ( the liquid flow, the inlet temperature, media conductivity, pulse width and frequency, and applied peak voltage) on the distribution of electric field strength, the liquid velocity and turbulence pattern, and the temperature distribution in the tube.

So some advice or examples will be very useful for me ,

Thanks a lot and best regards,

Mindaugas

Thanks a lot ! , You are right. I am planing use this function to express pulsed electric field. I have acrylic tube in which inner wall is inserted two parallel electrodes (Ground and Potential). Dielectric in tube inside is a fluid. This fluid must flow through the tube. First of all, I want to see distribution differences between pulsed electric field and stationary electric field. Secondly, very interesting for me is distribution differences of heat dissipation. So I want to develop model which could be used to analyse the impact of different process parameters ( the liquid flow, the inlet temperature, media conductivity, pulse width and frequency, and applied peak voltage) on the distribution of electric field strength, the liquid velocity and turbulence pattern, and the temperature distribution in the tube. So some advice or examples will be very useful for me , Thanks a lot and best regards, Mindaugas
Mindaugas Visockis
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年12月29日 GMT-5 13:30
Hello everybody,

I would be very thankful if somebody help me to find .mph example or some video about heat transfer in fluid when this fluid is treat 30 000 V pulse train and effect turbulent flow ?

DV*(flc2hs(mod(t[1/s],1/f)-1e-9,1e-9)-flc2hs(mod(t[1/s],1/f)-tp,1e-9))

DV - 30 000 V

Thanks a lot,

Mindaugas
Hello everybody, I would be very thankful if somebody help me to find .mph example or some video about heat transfer in fluid when this fluid is treat 30 000 V pulse train and effect turbulent flow ? DV*(flc2hs(mod(t[1/s],1/f)-1e-9,1e-9)-flc2hs(mod(t[1/s],1/f)-tp,1e-9)) DV - 30 000 V Thanks a lot, Mindaugas

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content