Initial part of a response in Simulink: how to fade in?

Hello forum, I am trying to simulate the behavior of a 1x1 dynamic system, giving as input a sinusoidal signal (constant amplitude) with a variable frequency (from 0 Hz to 100 Hz, with a sweep rate of 2 Hz/s). The problem is that, not knowing the initial conditions of the output, the response of the system shows oscillations in the first part (see picture below):

How to avoid this? I would like to see a very clean response, similar to the input signal

[Tony Mohan Varghese]

Please provide more information regarding the code that you use to generate the output.