Specifying Parameters as a Function of Time
For transient simulations, you can specify ambient temperature (in Design Settings) and certain thermal boundary condition parameters vary as a function of time. You can define different types of variations, including linear, power law, exponential, sinusoidal, piecewise linear, and square wave. For example, in the block boundary condition, you can specify the Total Power parameter as Transient and click Edit to open the Advanced Time Variations dialog box.
Linear
where 
is the time, 
is the value of the variable at time 
, 
is the value of the variable at 
= 0, and 
is a constant.
Power Law
where 
is the time, 
is the value of the variable at time 
, 
is the value of the variable at 
= 0, and 
and 
are constants.
Exponential
where 
is the time, 
is the value of the variable at time 
, 
is the value of the variable at 
= 0, and 
and 
are constants.
Sinusoidal
where 
is the time, 
is the value of the variable at time 
, 
is the value of the variable at 
= 0, 
is the period, 
is the phase shift, and 
is a constant.
Piecewise Linear
where 
is a function of time, 
is the value of the variable at time 
, 
is the multiplier value applied to the variable parameter defined in the piecewise linear dataset (y-axis value). See Using Datasets to Define Transient Parameters for information on defining 
using the Add Dataset dialog box.
Square Wave
where 
is the value of the variable at time 
and 
is the value of the variable at 
= 0. 
is a function of time as shown in the following figure.
The Phase is the time between 
= 0 and the first peak of the square wave. The On Time is the time that the square wave is at its peak value. The Off Time is the time between peak values of the square wave. The Off Value is the value of the square waves between the peaks of the wave. The peak value is the specified value of the transient quantity