Hello, everyone, and welcome back.
This lecture will be slightly longer here.
In this lecture, we will learn how to connect electrical circuit to a multi physics model.
This is the most interesting part and the most important part of the electric circuit module, because
electric circuit by itself is not that useful unless you connect it to the other physics in comsol multi
physics software.
So, um, let's start.
So at first we will create the electrical circuit to do that.
I will go to physics, then click on Add Physics.
And then here inside of AC DC, you should have electrical circuit click on electrical circuit.
And then click on Add to Component.
When you click on Add to Component, the electrical circuit should be added in your file.
So first I want to add a voltage source.
So right click click on voltage source and in the voltage source go on and select AC source.
The voltage is one volt and phase is zero and then again go to electric socket.
Right click.
Click on Add a register again, right click, click on register.
So I have to register one voltage and then we will change the nodes.
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
source.
In the voltage source, we have 1 to 0.
So this is a very small circuit where the potential source is from ground to node one and a rest is
connected from 1 to 2 and then from 3 to 0 we have another resistance which is connected to the ground.
And now the most important part of that is we need to create a multi physics model, and then we will
try to connect it.
So I will go to geometry and then inside of geometry let me create a cylinder because we are planning
to make a model where we have a cylinder that is a resistor in a form of a cylinder for easy understanding.
So here, let me write the radius to be two.
Mm.
And the height that is the length to be 25.
Mm.
And maybe let it lie along the x axis and I'll click on Build an Object.
So I have the cylinder ready now in the material I'll just click on blank material.
So let it be.
I will change the settings later.
And now let me add one more physics.
So I'll go to physics and then click on electric currents.
And then click on add to Component.
Now let me drag the electric current to the top.
And if I go into materials, you will see that I need to add the value.
So for simplicity, I will just take the electrical conductivity to be one same in parameter and permit
it to be one because this is just for demonstration.
So what's next here in the electrical current?
We have to add our terminal and again, we have to add one more terminal.
So the terminal one.
We have to select one face and in the terminal two, we have to select the other face.
Now, here's the interesting part.
In the terminal one, we have to select a terminal type circuit, and in the terminal two, we have
to select circuit again.
So now the next part that is you have to add the external eye versus V.
So if you go on.
To external I versus you.
You can click here and you can right click and duplicate to create once more.
Now, in the first setting here, I want to place it from node 2 to 0 and in the potential you have
to select terminal voltage one.
Similarly, select the other i versus you and.
Here, select 3 to 0.
And then in the plant potential select terminal voltage from the easy physics.
So let us understand what is happening here.
Now, in the electric circuit, we have two terminals and the terminal type is circuit.
So we have two terminals on the two end of the cylinder.
Now the value of the potential and current will be fed from the circuit and the values will get from
the elliptic circuit of physics.
So here, from the node 2 to 0, the potential drop V will be sent back to terminal one.
Similarly here, the potential will be sent to terminal two and then the simulation will happen and
it will calculate the resistance and so on.
So hope you got the idea how it works.
So now our next task is to add a study.
So here I will add a stationary study.
And then in the study I can have a frequency domain study.
I have to use my arrows.
So I'll go to frequency domain, frequency domain and select.
So here I'll not use the stationary.
So I'll just right click and disable it in the frequency domain.
Let me just test the model.
So at heart I, I'll just scan the model at ten hertz.
And as you can see that both the module are used and I will run the model.
Let's see what happens.
So the simulation has started?
Yes.
And the simulation is done.
So let's see what is going on.
I'll just close the study tab.
And as you can see, the maximum potential drop we have is 0.74 and the minimum is 0.25.
So let's see what is going on in a little circuit.
We have a voltage source of one volt and then it is connected to a resistance and another resistance
at 3 to 0.
Then we have external versus V from two.
That is after Ester one.
And the other external point is connected from 3 to 0 and three is connected to resistance two also.
Now these two nodes are then feedback to the terminals of the electric current.
And the electric current as a whole is a multi physics problem because here we define our material and
try to simulate the value of resistance in the material.
So this is how we solve the problem.
So as you expect, since the potential drop in total is one volt and we have few resistor connected
to it, here we have 1000 ohm and the other resistance is also 1000 ohm.
So we get a potential drop across the cylinder to be 0.75 fold.
So let me change the value of resistor.
Let me take this.
Let's say one ohm and the other resistance is also one ohm and try to simulate.
Let's see what kind of result we'll get.
Maybe we'll get close to one volt.
Yeah.
As you can see that the maximum volt is one volt in the model because the distance is too low.
That is one ohm.
So most of the potential drop will occur through the cylinder.
So this is how you solve the multi physics problem using the electric circuit model in comsol metaphysics.
Hope you liked it.
Thanks for watching.
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Have a nice day.