# Transient analysis time step

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 February 25, 2013, 04:12 Transient analysis time step #1 Senior Member   Govindaraju Join Date: Apr 2010 Posts: 206 Rep Power: 8 Dear all I would like to clarify the time steps. I have a sinusoidal function and the frequency is 1 Hz. I did the transient simulation for one cycle one of my friends told me and insist me to do the multiple cycle simulations.Is it necessary to do the simulations for multiple cycles?. If I do the multiple cycles the solution time is too large. Is there any way to short cut. Thank you Regards

 February 25, 2013, 05:15 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,669 Rep Power: 84 If you want the startup transient then you do not need to do multiple cycles. If you want the repeating cycle it depends how long it settles to a repeating pattern. It could be 1 cycle, it could be hundreds - it depends on how stable the system is and how long it takes to settle. But you will need to run it long enough to show that you have run long enough - so the change in the last few cycles is small enough that you can call it converged.

 February 25, 2013, 06:55 #3 Senior Member   Lance Join Date: Mar 2009 Posts: 522 Rep Power: 11 Glenn is (as always) correct, you will need to perform a sensitivity analysis on the number of cycles in order to avoid initial effects - otherwise the initial conditions will affect your solution.

March 2, 2013, 21:01
#4
Senior Member

Govindaraju
Join Date: Apr 2010
Posts: 206
Rep Power: 8
Quote:
 Originally Posted by Lance Glenn is (as always) correct, you will need to perform a sensitivity analysis on the number of cycles in order to avoid initial effects - otherwise the initial conditions will affect your solution.
Dear all

I have a set of data from 0 s to 2 s. I used one dimensional interpolation and activated extended minimum and maximum.

My question is

How to run this simulation for repeated cycles.( at least for 4 cycles) ?

Thank you

Regards

Govind

 March 3, 2013, 06:19 #5 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,669 Rep Power: 84 The simple nasty approach is just to repeat the 1D function 4 times. The better approach is to use the mod function, so the time input to the interpolation is t-mod(t,2) which should return a function which increase to 2, then goes to zero and increases to 2 again when t is 4, and repeats that forever.

March 3, 2013, 14:14
#6
Senior Member

Govindaraju
Join Date: Apr 2010
Posts: 206
Rep Power: 8
Quote:
 Originally Posted by ghorrocks The simple nasty approach is just to repeat the 1D function 4 times. The better approach is to use the mod function, so the time input to the interpolation is t-mod(t,2) which should return a function which increase to 2, then goes to zero and increases to 2 again when t is 4, and repeats that forever.
Dear Mr Glenn

Thank you . It works

Govind

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