Discussion Forum

Hi Harris,

I assume that by time-dependent potential you mean that you are applying a voltage as a boundary condition of your model, and that you have a working model to simulate the stationnary conditions.

In that case, in the field where you normally set the applied voltage, simply write whatever time-dependent expression, using the built-in variable t. This variable can only be accessed in time dependent studies.

You can also define a variable Va_t to write this expression, and type Va_t in the field for the applied voltage. Because the variable t is defined at the component level, you can not do this using global parameters, you must use component-level variables.

Hai Alexis,

What I need to do is that solve the model in time dependent solver for total of 10 seconds. Further, for the initial 10s I want my potential to be 10V and after 10s the potential should change to another constant value (0, 5, 20,..). I don't want potential to change continuously with time, I want to apply potential in some form similar to that of a square wave.

This can be done using Global Definitions > Functions > Rectangle.

Alternatively, you can look-up "Events" in the user-guide. This is oftentimes better-suited for abrupt transitions like yours.

But how can I add this rectangle function as my potential in the electrostatic node?

When you define the function, you will give it a name. Simply use that name in the expression of the applied potential.

Thank you for your patience Alexis, I am able to change material property in form of function, but in other physics nodes I can't change the variables into a function, it says unknown variable. Same when I try to add a varible as a function in global. I think I am making some simple mistake some where.

Hi Harris,

I am unsure about how to help you. How are you setting the voltage at the moment? Perhaps consider providing screenshot(s) or attaching your model.

I was able to do this with analytic funtion, but finding difficult to doit with rectangle. By the way using events work like a charm. I am attaching the screencshot of using the rectangle function as potential, probable some error somewhere.

rect1 is just the function name. You must call it with some argument.

For example use V0*rect1(sin(2*pi*f*t)) to obtain a periodic rectangular function with frequency f and magnitude V0. V0 and f can then be parameters that you define (in volts and Hz, respectively), whereas t is a built-in variable representing time.

But I think in your case, the function waveform is more appropriate, because you can directly select Type: Square and Angular frequency: f to get the same result.

Anyway, the point is that the function must be called func_name(argument) by something that is time dependent ;-)

Thanks Alexis, The problem is solved, I was only giving an argument as t, then my unit of potential won't be voltage. It was V*s, that were the problem. thank you very much for your help.