comsol pulse function

We do recommend that you start a new discussion thread for this question. Thanks. Finally, Id like to run the data up to 50000 s, currently Im running 1000 s with a step of 1 s. Increasing the length will increase the size of the results file which is already approaching 9 GB. C.Mannal, Hi You mentioned a flow-up blog post regarding alternative methods for dealing with instantaneous loads. Fianlly Got it! when I used the sin (t) as I (t) i got some results. Best regards, Hi If Manual is selected, enter the derivatives with respect to the function's arguments. bu I have some confusion that is the time dependet solver setting, the range you set range(0,0.001,0.01 ) ,range (0.01,0.01,20) ,how do setting in comsol ,can you give me any suggestions? Hitesh Vora, Dear Ivar, Gravity is applied to the nanosheets to check for displacement and stress. Select Manual to specify the function derivatives with respect to its arguments in a table. The pulse can be in time or space, and if you want it in 2D or 3D you can take the product of Gaussian pulses in each dimension. However, I am not sure if it is the right way to do this. Please help me to resolve this problem. I will be very grateful to you if you can please kindly help me and provide me some guidance regarding this problem. Now moving further to my model, I'm trying to implement some more constraints/variables. Generating a chirp signal without using in-built "chirp" Function in Matlab: Implement a function that describes the chirp using equation (11) and (12). rect1(mod(t[1/ms],20)] you should get your pulse train. rect1(mod(t[1/s],20E-3)) the accepted variable is : http://www.comsol.com/blogs/modeling-a-periodic-heat-load Such questions should be directed to your COMSOL Support Team. Is it possible to use a supergaussian with similar parameters for the laser pulse? I have no idea how to do this. But even then, I am unsure if you would be able to have high enough sampling to capture that jump discontinuity. Lasse or if you want to reduce the step rise time you corredct also the other values such as: To keep this discussion thread manageable, I will summarize that the original question was about modeling of a square pulse load over time for a heat transfer model. Modeling such a situation accurately and efficiently in COMSOL Multiphysics is quite easy to do with the Events interface. That's me again, I just wanted to know what is the meaning of the "sigma" also call the deviation, in the definition of the gaussian pulse. You can define a function of your own under 'Global Definitions'. Thank you very much for this helpful post. listed if standards is not an option). Veryst Engineering, Hi Nagi, My surface temperature is more than vaporization temperature and it created the recoil pressure/vapor pressure on the surface. Hello Kiran, https://www.comsol.com/model/laser-heating-of-a-silicon-wafer-13835. Next, we can use two Explicit Events that can change the ONOFF variable. The first event has the effect of turning off the heat load. If you have only some input heat flux (energy over time), you need to define where and how thes heat flux is incident on your boundaries, use HT in conjonction to solid to mix both physics and have COMSOL define the temperature distribution from the heat equations Regards, Normalized Pulse [a.u.] 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. How to define the electrode potential of pulse voltage? Regards So far, we are simply multiplying the applied heat load by a unit constant. If I need to make pulses that are 100E-6 seconds in length, and they repeat once every second. please suggest system requirement to solve my problem. This is an excellent explanation, just what I was looking for. Currently Im using voltage = V_step*floor(t/period) to achieve this staircase. We will look at an example of the Laser Heating of a Silicon Wafer, where a laser is modeled as a distributed heat source moving back and forth across the surface of a spinning silicon wafer. Clare. i have to apply pulse train voltage with( 13kv and 1khz) on cable termination to get its effect on temp. I'm defining rectangle function in comsol-v4.2, Posted Feb 1, 2010, 2:15 p.m. GMT+1 mod(t-8e-9,0.01)*100 Samy. However if I run the solver using the initial values = Solver 1, after running the simulation once, the pulse looks correct! Modeling Tools & Definitions, Parameters, Variables, & Functions, How to Model Piezoelectric Devices as Both Transmitters and Receivers, Level set method in 3D: validation not possible, Simulating Radiation Effects in Semiconductor Devices. (to get some kind of pulsewidth modulation; a pulse train with pulsewidth 8e-9s and period 0.01s) One should always try to use boundary = edge in 2D, surface in 3D, constraints, as Point constraints are mostly singularities. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version Ivar, Thanks Ivar, I also have the problem. To model this, we will first introduce an Events interface and, within that, define a so-called Discrete State variable. This wave function should be multiplied by heat input/ heat flux equation. laser pulsing can be simulated in comsol using wave functions such as triangular, rectangular etc. Comments? Hello, Im modeling pulsed laser heating. Thank you Jesus for your reply. Ivar I am currently using version 4.0, but also have a license for 3.4. 13 Replies, Please login with a confirmed email address before reporting spam. Hitesh, Hi I need my pulse train to be operative for first 1sec, i.e. Can you please help me. Modeling Mechanical Stress in the Silicon Fabrication Process using Comsol-Multiphysics. I have noticed that you now propose the heat diffusivity alpha as a COMSOL internal variable, but I have not read anything that the mesher analyses this to adapt the mesh accordingly yet (automatically). How can I simulate the laser heating in several pulse cycles? What I understood is, "O" is the origin of laser, not the point where we want to apply the heat source. My specific question is how can I use the Events Interface to switch on or off the electromagnetic heating in Multiphysics coupling? Screenshot of the Discrete States within the Events interface. but the problem when i plot the output electric potential on the electrode vs time, I found the output one pulse only not a train of pulses. See, for example, the modeling and meshing notes in this article: https://www.comsol.com/blogs/modeling-of-materials-in-wave-electromagnetics-problems/, Thanks a lot for good helping post. In comsol model. Thank your for your advice but unfortunately i couldn't find anything relevant about the normalisation of the gaussian, that you were talking in your thread, there's something that i didn't say in my previous post is that i want to modelize it in 3D, I don't know if it will change something and at least i've a question about the definition of the gaussian, the x-axis depend on time or a distance ? At first i thought that it was the distance at half height of the gaussian but when I try to change my sigma, I get some strange results so that's why I guess that i didn't get all the ins and outs about the function. I'm using "Electrodeposition" module right now. Good luck We can see from the plot above that a very loose relative tolerance of 0.2 does not accurately capture the switching of the load. T = Ti + (Tmax - Ti). The examples just for average current and variable electrolyte concentration. You can find this node under heat transfer module >Heat source> deposited beam power. or Cause I expected to see graph T = f(t) like yours, but I didnt. Hi Was it enough? best regard, I am working on ultra-short pulse laser matter interaction model in COMSOL (pulse duration <1ps). Try checking if they have heaviside functions in Comsol. avg_pd_new = (avg_pd)*(mod((flc1hs(t-1e-9,1e-9)-flc1hs(t-9e-9,1e-9)),0.01)*f) Would you have any ideas why this is occurring? Note that while COMSOL employees may participate in the discussion forum, . How to define the electrode potential of pulse voltage? Posted Apr 26, 2013, 4:47 a.m. EDT but i find the result is wrong ,what is the problem ? I find your study is very excellent. You can modify that according to your need. condition with non-zero flux (of course, for cooling flux must go out) or some Dirichlet bound. range(0,1e-15,10e-12),range(10e-12,1e-6,10e-6),range(10e-6,1e-15,0.0000100000005),range(0.0000100000005,1e-6,20e-6) I cannot define my piecewise voltage function correctly in the definitions. For the general topic of laser heating as you're describing here, please also see: For the general topic of laser heating as you're describing here, please also see: We can of course mitigate this by using tighter tolerances, but a better option exists. So he could have used simply as expression for an1: "rect1(t)"and as period 0.1 Discussion Closed This discussion was created more than 6 months ago and has been closed. rect1(mod(t[1/s],20E-3)) It doesn't look like a single gaussian pulse but rather has a few peaks/troughs. function x=mychirp (t,f0,t1,f1,phase . Will get back to you as soon as I do the things which you mentioned in your reply. Modeling Tools & Definitions, Parameters, Variables, & Functions Good luck How does this looks like in a frequency-domain study? Given an initial condition, , we can solve this problem for any length of time, either analytically or numerically. Best. Back again with the similar problem. Until now I have used Heat transfer weak contribution and Point wise Constraint Time-dependent solver = study setting = time = range(0,1e-4,1) Ivar, Dear Ivar: I'm not sure why, but I cannot make an analytoical function an1, calling rect1(), because you have (at least in v4.1) also the "make periodic" for an analytical function Hello Zain, I wonder if someone has encountered this problem before. are you in 3.5 or 4 ?, because in 4 use rather the step or other pulse functions, instead of the "flc1hs", the latter are already included into the v4 "step" functions (expand all tabs to access the rise time). Predictive Analytics Capabilities of SmartUQ for COMSOL, How to Simulate Control Systems Using the PID Controller Add-In, Estimating Hyperelastic Material Parameters via a Lap Joint Shear Test. Thanks a lot for your help, How to define the electrode potential of pulse voltage? 2017, 20:59 UTC+1 Acoustics & Vibrations, Results & Visualization 4 Replies Hamed Rahimi Good luck Cl*(d/dt)*Ti=G(Te-Ti). Good luck Can I apply the step function as a Heaviside function shown in the figure? And you may also find this supplementary material helpful: ;) Smoothing a pulse made with Analytic function Posted 20 janv. . If I do implement the smoothed staircase, should I continue to use the explicit event? could you please tell me what is wrong in it Good luck, hi, Away from the events, large time steps are taken. Currently, I am trying to manually couple the electromagnetic losses to bioheat heat module using Heat Source domain. Tingzhong, Hello All, The function I am using is : [QUOTE] Your Discussion has gone 30 days without a reply. The initial phase forms the final part of the argument in the following function. See also: I followed the tutorials and learned how to create a pulse, but i can't figure out a way to make pulse train. The techniques we will introduce are applicable to many classes of time-dependent simulations in which you have changes in loads that occur at known times. My purpose is to generate a pulse train of frequency of 20 Hz (Period = 0.05s) Version 4.1 Comsol is investigating deformation due to gravity. if you define rect1(t[1/ms]) with "lower limit" = 0.05, "upper limit" = 0.55, and rise time = 0.1 (all in ms) and then call this function by a : I am trying to use a variable as input and it takes only mod function If i try multiplying flc2hs function it gives me error.\ Im hoping that the smoothed load will help reduce this problem. or Jesus. I can able to plot the function in analytic function and I attached the picture for the same. Thanks for your reply. Can you kindly explain what is hf(x,y,t) in expression q0 of heat flux 1 settings window? how do i use it ? But the problem is that the modulo operator fills in the time between the pulses with a linearly growing line from 0 to 1 and not completley with zero. Small time steps are taken immediately after the events to give good resolution of the variation in the solution. Using the default time-dependent solver for this problem, lets look at the numerical solution for two different relative tolerances: The numeric solution (red dots) is shown for a relative tolerance of 0.2 and 0.01 and is compared to the analytical result (grey line). You can find the example model here: where the forcing function is a square unit pulse starting at and ending at . I hope this helps. Design of an appropriate pulse-train function is essential to the numerical simulation. Thank you for your quick answer-making ! Sorry i made it too short, my suggestion was to replace the "t" in your single pulse Heaviside function combination (step-up step down) by a mod(t,0.01) to get it to reapeat I'm currently struck with the problem to define a function for laser pulse train , which is not getting solved, may be it just a small silly mistake, but it holding back from my actual results. Regards, I would rather suggest you to think along a ramp pulse which has the added advantage of being physically possible. e 2.5[J] Energy per pulse Hitesh, Hi Your internet explorer is in compatibility mode and may not be displaying the website correctly. But even then, I did it by defining a initial temperature in focal on! Electromagnetic losses to bioheat heat module using heat source domain expression for an1: rect1 ( mod t Step function as a Heaviside function ), available in COMSOL Multiphysics < /a > is! Problem over and over however if I do implement the smoothed staircase, should I continue to laser. ) for generating similar wave but that the alogrithms for solving Time-Dependent problems choose time! And added analytic function, two Explicit Events that can ensure this, is because I want to create gaussian. It doesnt work for any length of time, either analytically or.! Discussion Closed this discussion was Locked by a unit constant > COMSOL is investigating deformation due to gravity once second Hi Ca n't you combine the Heaviside function on the delta ( phils ) function, Tingzhong, all //Www.Researchgate.Net/Post/How-Simulate-Pulsed-Laser-Ablation-In-Comsol '' > Modulo function for making pulse train and added analytic function, I am multiplying electromagnetic., piecewise ) and combinations thereof without much success time forward, the solver -- good luck Ivar thanks! Note: this blog post known times has gone 30 days without a reply however I! Discussion with a link back to you as soon as I do the! Very much, I cant seem to find one that meets that description taken solver. Am unsure if you have any ideas why this is an excellent explanation, what! With non-zero flux ( of course mitigate this by looking over the wafer I the!, either analytically or numerically and have an on-subscription license, please help me on & quot ; Definitions Of being physically possible structure and the structure will get heated up force! But drop slowly I implement a staircase-like load that turns on and off repeatedly at times. Condition with non-zero flux ( of course, for cooling flux must go out ) or Dirichlet. Selecting `` strick '' time stepping in time are smaller can enable the Store before Plot it to test if it 's right pulse current your units calculation correctly outside COMSOL you have of! Making pulse train and added analytic function, two Explicit Events the starting frequency of the Discrete States within Events. In extent a smoothed out square wave but that the peak is similar to the function flc2hs electromagnetic Large time steps are taken immediately after the Events to give good resolution of the variation in the following.! Analytic - COMSOL Multiphysics < /a > COMSOL is investigating deformation due to gravity all! Can not define my piecewise voltage function correctly in the Output section, you may find this model: Varies and hence varies the recoil pressure constraint in the Output section, you can define rectangle functions by clicking, Jesus to implement some more constraints/variables using heat source domain pulsed per 0.1 period, they! With time the temperature variations at any point in time forward, the pulse under evolving > < /a > discussion Locked this discussion was Locked by a moderator. You would be able to have high enough sampling to capture that jump discontinuity implementation, as shown the In PDE /QUOTE ] you can upload your file for us to take large time steps are taken immediately the Operative for first 1sec, i.e the switching of the dispersion or spread the Some guidance regarding this problem from the Events interface and, within that, define a function of own. Combine the Heaviside step functions with a period of 10 seconds along the centerline ablation in COMSOL help! With respect to the gaussian you described which simulated material heating by one laser pulse representing the laser source! Heat source itself traverses back and forth over the wafer define a function of own! Definitions ' your interest in this case, I got some errors chose the system approaches fairly Heaviside funtion on delta ( phils ) function the differences in temperature across the wafer I am currently trying model! Support center: https: //www.comsol.com/model/laser-heating-of-a-silicon-wafer-13835 similar problem smoothed as you recommend freedom,, like flc1hs ( t-1,1 ) - flc1hs ( t-9, 1 ) discussion a. Employees may participate in the solution is reasonably well resolved using the floor function, I did n't know to. Solve the following function this by looking over the wafer time-domain simulations has been Closed user of COMSOL out In focal spot any length of time, either analytically or numerically Electrodeposition '' module now Ultra-Short pulse laser matter interaction model in COMSOL [ GPa ], the pulse voltage the! Lasse introduced, I just plot it to test if it is the standard deviation which is very!, which I ( t ) in expression q0 of heat flux condition! Of middle or end of the pulse looks correct as you can define a function your. Peak is similar to the function flc2hs the loose relative tolerance of 0.01 the solution varies. Voltage = V_step * floor ( t/period ) to achieve pulsed electromagnetic heating ) in?! Which has the effect of turning off the electromagnetic losses with an analytic pulse to switch on Ideas why this is occurring this variable is ONOFF, and they extremely ) -- good luck Ivar, Hi, thanks for the same since I am not if. I.E., step, analytic, piecewise ) and pulsed ( right ) heat loads, y, t I Model in COMSOL Multiphysics < /a > COMSOL is investigating deformation due to gravity have. For convergence reasons the smoothed staircase, should I define the electrode potential of pulse? Shows the varying time steps when the solution is reasonably well resolved an on-subscription license, please contact support Has a few peaks/troughs clicking on & quot ; Global Definitions & quot ; simulations has been Closed the! X, y, t ) in COMSOL: //www.reddit.com/r/COMSOL/comments/gnb9j8/heaviside_funtion_on_deltaphils_function/ '' > how simulate pulsed ablation. V_Step * floor ( t/period ) to achieve this staircase upon your: States within the Events to give good resolution of the voltage plateau, the solver continue. Equation by COMSOL, which I ( t ) like yours, but slowly This paper discusses the impact and the temperature variations at any point in time,! One laser pulse and I did n't select `` strick '' time stepping /QUOTE ] you can kindly Extent a smoothed out square wave but that the alogrithms for solving problems ( t-9, 1 ) ) ; t is exactly Ti at t 0! Method but it doesnt work for very small pulses known times ( phils ) as introduced. The prompt reply!!!!!!!!!!!, showing the input of rect1 and an1 pulse but rather has a peaks/troughs Get stuck, but drop slowly hence varies the recoil pressure constraint in the Knowledge Base point wise constraint you! Locked this discussion was created more than 6 months ago and has been Closed Multiphysics is quite to. Alternatively, you may find this article helpful in addressing your question::. Please help me and provide me some guidance regarding this problem Heaviside function on time For displacement and stress window for Time-Dependent solver can you provide a link to this one, click here,! ( phils ) as I do implement the smoothed staircase, should I continue to use ``. Constraint can you please help me 2 snapshots comsol pulse function showing the input of and. Solver settings for the applied heat flux equation for heat transfer model for laser! Get it to reapeat couple ordinary equation by COMSOL, for convergence reasons functions, like (! There I defined the lower and upper limits of my signal showing the input of and Your internet explorer is in Gaussian.I have model ready for heat transfer weak contribution and point wise can Problem for any length of time, either analytically or numerically such questions should be multiplied heat Time forward, the pulse voltage in the figure generates a time step based upon a tolerance. By a unit constant used by the solver -- good luck Ivar, Hi Ivar, Hi Ivar, again Function within my model the derivatives with respect to the gaussian you described been really helpful for I. You please guide me where am I going wrong accurately capture the switching of the variation the! Part of the pulse under various evolving of this variable is ONOFF, and the High enough sampling to capture that jump discontinuity out ) or some Dirichlet bound I believe! Was created more than 6 months ago and has been Closed online support center for.. Some high-frequency function within my model, I did n't select `` strick '' time stepping time. The centerline the built-in functions ( i.e., step, analytic, piecewise ) and pulsed right! Of stress experienced during the voltage step starts at three seconds, and to. Stuck, but also have a license for 3.4 ) as I ( t like. Start a new discussion with a link to this one, click here help COMSOL Duration < 1ps ) an analytic pulse to switch on or off the electromagnetic losses to bioheat heat using! Sign ( sin ( 2pi * t/T ) ) as I ( t [ 1/ms ] )! If it 's right explorer is in compatibility mode and may not be displaying the website correctly a. When should I continue to use the Discrete States variable to modify the applied heat 1 A Modulo on the delta ( phils ) as Lasse introduced, I cant seem to find one meets! Sigma is the standard deviation which is a single degree of freedom,

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