WEBVTT 00:04.120 --> 00:06.610 Hello, everyone, and welcome back. 00:06.640 --> 00:10.270 This lecture will be slightly longer here. 00:10.270 --> 00:17.410 In this lecture, we will learn how to connect electrical circuit to a multi physics model. 00:17.440 --> 00:27.430 This is the most interesting part and the most important part of the electric circuit module, because 00:28.330 --> 00:36.540 electric circuit by itself is not that useful unless you connect it to the other physics in comsol multi 00:36.550 --> 00:37.600 physics software. 00:37.990 --> 00:40.930 So, um, let's start. 00:40.930 --> 00:46.240 So at first we will create the electrical circuit to do that. 00:46.240 --> 00:51.460 I will go to physics, then click on Add Physics. 00:53.720 --> 01:03.860 And then here inside of AC DC, you should have electrical circuit click on electrical circuit. 01:05.100 --> 01:07.770 And then click on Add to Component. 01:09.630 --> 01:15.840 When you click on Add to Component, the electrical circuit should be added in your file. 01:15.870 --> 01:19.680 So first I want to add a voltage source. 01:20.310 --> 01:30.090 So right click click on voltage source and in the voltage source go on and select AC source. 01:31.620 --> 01:39.180 The voltage is one volt and phase is zero and then again go to electric socket. 01:39.660 --> 01:40.620 Right click. 01:41.720 --> 01:48.230 Click on Add a register again, right click, click on register. 01:48.350 --> 01:54.530 So I have to register one voltage and then we will change the nodes. 01:54.980 --> 02:14.000 So for Ester one, we have B from 1 to 2 and four register to two, we have 3 to 0 and we'll go to voltage 02:14.000 --> 02:14.750 source. 02:16.040 --> 02:19.940 In the voltage source, we have 1 to 0. 02:20.300 --> 02:27.530 So this is a very small circuit where the potential source is from ground to node one and a rest is 02:27.530 --> 02:36.350 connected from 1 to 2 and then from 3 to 0 we have another resistance which is connected to the ground. 02:38.060 --> 02:47.210 And now the most important part of that is we need to create a multi physics model, and then we will 02:47.210 --> 02:48.350 try to connect it. 02:49.040 --> 02:59.150 So I will go to geometry and then inside of geometry let me create a cylinder because we are planning 02:59.150 --> 03:08.000 to make a model where we have a cylinder that is a resistor in a form of a cylinder for easy understanding. 03:09.230 --> 03:15.250 So here, let me write the radius to be two. 03:15.650 --> 03:16.350 Mm. 03:19.180 --> 03:24.850 And the height that is the length to be 25. 03:24.850 --> 03:25.510 Mm. 03:26.200 --> 03:32.380 And maybe let it lie along the x axis and I'll click on Build an Object. 03:32.650 --> 03:41.350 So I have the cylinder ready now in the material I'll just click on blank material. 03:42.250 --> 03:43.240 So let it be. 03:43.720 --> 03:45.670 I will change the settings later. 03:46.270 --> 03:49.600 And now let me add one more physics. 03:49.600 --> 03:54.520 So I'll go to physics and then click on electric currents. 03:54.880 --> 03:57.100 And then click on add to Component. 03:59.080 --> 04:04.630 Now let me drag the electric current to the top. 04:06.980 --> 04:11.630 And if I go into materials, you will see that I need to add the value. 04:11.810 --> 04:19.880 So for simplicity, I will just take the electrical conductivity to be one same in parameter and permit 04:19.880 --> 04:24.080 it to be one because this is just for demonstration. 04:25.010 --> 04:29.780 So what's next here in the electrical current? 04:30.200 --> 04:36.860 We have to add our terminal and again, we have to add one more terminal. 04:36.860 --> 04:39.560 So the terminal one. 04:42.270 --> 04:48.090 We have to select one face and in the terminal two, we have to select the other face. 04:49.080 --> 04:51.210 Now, here's the interesting part. 04:51.600 --> 05:00.870 In the terminal one, we have to select a terminal type circuit, and in the terminal two, we have 05:00.870 --> 05:02.220 to select circuit again. 05:02.220 --> 05:10.680 So now the next part that is you have to add the external eye versus V. 05:13.850 --> 05:15.890 So if you go on. 05:18.110 --> 05:21.050 To external I versus you. 05:21.080 --> 05:26.510 You can click here and you can right click and duplicate to create once more. 05:27.170 --> 05:41.330 Now, in the first setting here, I want to place it from node 2 to 0 and in the potential you have 05:41.330 --> 05:44.030 to select terminal voltage one. 05:44.870 --> 05:50.450 Similarly, select the other i versus you and. 05:52.260 --> 05:56.550 Here, select 3 to 0. 05:57.570 --> 06:04.700 And then in the plant potential select terminal voltage from the easy physics. 06:04.710 --> 06:07.080 So let us understand what is happening here. 06:08.640 --> 06:15.150 Now, in the electric circuit, we have two terminals and the terminal type is circuit. 06:17.100 --> 06:22.050 So we have two terminals on the two end of the cylinder. 06:23.070 --> 06:32.430 Now the value of the potential and current will be fed from the circuit and the values will get from 06:32.430 --> 06:35.040 the elliptic circuit of physics. 06:35.880 --> 06:45.630 So here, from the node 2 to 0, the potential drop V will be sent back to terminal one. 06:46.110 --> 06:54.000 Similarly here, the potential will be sent to terminal two and then the simulation will happen and 06:54.000 --> 06:56.250 it will calculate the resistance and so on. 06:57.330 --> 07:00.570 So hope you got the idea how it works. 07:01.320 --> 07:05.310 So now our next task is to add a study. 07:05.640 --> 07:09.900 So here I will add a stationary study. 07:10.380 --> 07:19.440 And then in the study I can have a frequency domain study. 07:19.620 --> 07:21.150 I have to use my arrows. 07:22.590 --> 07:28.530 So I'll go to frequency domain, frequency domain and select. 07:30.060 --> 07:33.780 So here I'll not use the stationary. 07:33.780 --> 07:38.460 So I'll just right click and disable it in the frequency domain. 07:38.970 --> 07:41.790 Let me just test the model. 07:41.790 --> 07:47.220 So at heart I, I'll just scan the model at ten hertz. 07:48.930 --> 07:55.240 And as you can see that both the module are used and I will run the model. 07:55.260 --> 07:56.520 Let's see what happens. 08:00.050 --> 08:02.330 So the simulation has started? 08:02.360 --> 08:03.110 Yes. 08:03.110 --> 08:05.000 And the simulation is done. 08:05.690 --> 08:07.760 So let's see what is going on. 08:07.790 --> 08:09.560 I'll just close the study tab. 08:09.830 --> 08:17.810 And as you can see, the maximum potential drop we have is 0.74 and the minimum is 0.25. 08:18.800 --> 08:21.780 So let's see what is going on in a little circuit. 08:21.800 --> 08:29.150 We have a voltage source of one volt and then it is connected to a resistance and another resistance 08:29.150 --> 08:30.890 at 3 to 0. 08:31.160 --> 08:34.100 Then we have external versus V from two. 08:35.120 --> 08:37.460 That is after Ester one. 08:37.790 --> 08:46.910 And the other external point is connected from 3 to 0 and three is connected to resistance two also. 08:47.690 --> 08:54.890 Now these two nodes are then feedback to the terminals of the electric current. 08:55.580 --> 09:04.460 And the electric current as a whole is a multi physics problem because here we define our material and 09:04.460 --> 09:08.750 try to simulate the value of resistance in the material. 09:09.680 --> 09:11.840 So this is how we solve the problem. 09:11.930 --> 09:19.940 So as you expect, since the potential drop in total is one volt and we have few resistor connected 09:19.940 --> 09:24.700 to it, here we have 1000 ohm and the other resistance is also 1000 ohm. 09:24.710 --> 09:29.960 So we get a potential drop across the cylinder to be 0.75 fold. 09:30.200 --> 09:32.210 So let me change the value of resistor. 09:32.240 --> 09:33.410 Let me take this. 09:34.400 --> 09:42.260 Let's say one ohm and the other resistance is also one ohm and try to simulate. 09:42.590 --> 09:44.870 Let's see what kind of result we'll get. 09:45.140 --> 09:46.760 Maybe we'll get close to one volt. 09:46.790 --> 09:47.060 Yeah. 09:47.090 --> 09:53.950 As you can see that the maximum volt is one volt in the model because the distance is too low. 09:53.960 --> 09:54.830 That is one ohm. 09:54.830 --> 09:59.540 So most of the potential drop will occur through the cylinder. 10:00.290 --> 10:10.340 So this is how you solve the multi physics problem using the electric circuit model in comsol metaphysics. 10:10.370 --> 10:11.600 Hope you liked it. 10:12.350 --> 10:13.430 Thanks for watching. 10:13.430 --> 10:20.120 And if you like the course, please do rate it because it is the only thing from where I get motivation 10:20.120 --> 10:21.740 to create more courses. 10:21.920 --> 10:26.090 So thanks for watching again and please do rate our course. 10:26.420 --> 10:27.380 Have a nice day.